MedWorm: H1N2

Genetic characterization of subtype H1 avian influenza viruses isolated from live poultry markets in Zhejiang Province, China, in 2011

Virus Genes — Wed, 18 Jan 2012 06:59:20 +0100

Abstract Nine avian influenza A viruses (AIVs), H1N2 (n = 2) and H1N3 (n = 7), were isolated from domestic ducks in live poultry markets in Zhejiang Province, Eastern China, in 2011. All viruses were characterized by whole genome sequencing with subsequent phylogenetic analysis and genetic comparison. Phylogenetic analysis of all eight viral genes showed that the viruses clustered in the Eurasian lineage of influenza A viruses. The hemagglutinin cleavage site of all viruses displayed features of a monobasic cleavage site. Although there was no evidence of re-assortment in subtype H1 AIVs among the avian species and mammalian hosts in this study, continued surveillance is needed considering the important role of the domestic duck in the dissemination and ...

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BPEX Pig Health Scheme: a useful monitoring system for respiratory disease control in pig farms?

BMC Veterinary Research - Latest articles — Fri, 30 Dec 2011 05:00:00 +0100

Conclusions: The study found statistical associations between levels of pleurisy recorded by BPHS at slaughter and the presence H1N2 and PRRSV in the herd. There is also some evidence that farms which submit pigs with these lesions may have reduced productivity. However, more research is needed to fully validate the scheme. (Source: BMC Veterinary Research - Latest articles)

Rare swine flu strain detected in Minn. infant

Health News: CBSNews.com — Wed, 14 Dec 2011 17:12:16 +0100

Second case ever detected of H1N2 virus, but not nearly as dangerous as H1N1 (Source: Health News: CBSNews.com)

Rare swine flu strain H1N2 detected in Minn. infant

Health News: CBSNews.com — Wed, 14 Dec 2011 17:12:16 +0100

Second case ever detected of H1N2 virus, but not nearly as dangerous as H1N1 (Source: Health News: CBSNews.com)

Media Myth On Relatedness Between Novel H1N2 and H3N2

Recombinomics — Sat, 10 Dec 2011 11:46:10 +0100

The commentary discusses the media myth on the relatedness between trH1N2, trH3N2, H3N2pdm11. (12/09/11 23:00) (Source: Recombinomics)

Novel H1N2 Case In Minnesota With H3N2pdm11 Genes

Recombinomics — Sat, 10 Dec 2011 11:46:10 +0100

The commentary discusses a novel H1N2 case in Minnesota with H3N2pdm11 genes. (12/09/11 16:30) (Source: Recombinomics)

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Genetic analysis and antigenic characterization of swine origin influenza viruses isolated from humans in the United States, 1990-2010.

Virology — Thu, 10 Nov 2011 05:00:00 +0100

Authors: Shu B, Garten R, Emery S, Balish A, Cooper L, Sessions W, Deyde V, Smith C, Berman L, Klimov A, Lindstrom S, Xu X Abstract Swine influenza viruses (SIV) have been recognized as important pathogens for pigs and occasional human infections with swine origin influenza viruses (SOIV) have been reported. Between1990 and 2010, a total of twenty seven human cases of SOIV infections have been identified in the United States. Six viruses isolated from1990 to 1995 were recognized as classical SOIV (cSOIV) A(H1N1). After 1998, twenty-one SOIV recovered from human cases were characterized as triple reassortant (tr_SOIV) inheriting genes from classical swine, avian and human influenza viruses. Of those twenty-one tr_SOIV, thirteen were of A(H1N1), one of A(H1N2), and seven of A(H3N2) s...

Genetic Characterization of H1N2 Influenza A Viruses Isolated from sick pigs in Southern China in 2010

Virology Journal — Thu, 13 Oct 2011 04:00:00 +0100

In conclusion, our finding provides further evidence about the interspecies transmission of avian influenza viruses to pigs and emphasizes the importance of reinforcing swine influenza virus (SIV) surveillance, especially before the emergence of highly pathogenic FMDs in pigs in Guangdong. (Source: Virology Journal)

Swine-Origin Influenza A (H3N2) Virus Infection in Two Children --- Indiana and Pennsylvania, July--August 2011.

MMWR Morb Mortal Wkl... — Fri, 09 Sep 2011 04:00:00 +0100

This report describes two cases of febrile respiratory illness caused by swine-origin influenza A (H3N2) viruses identified on August 19 and August 26, 2011, and the current investigations. No epidemiologic link between the two cases has been identified, and although investigations are ongoing, no additional confirmed human infections with this virus have been detected. These viruses are similar to eight other swine-origin influenza A (H3N2) viruses identified from previous human infections over the past 2 years, but are unique in that one of the eight gene segments (matrix [M] gene) is from the 2009 influenza A (H1N1) virus. The acquisition of the M gene in these two swine-origin influenza A (H3N2) viruses indicates that they are "reassortants" because they contain genes of the swine-orig...

Distribution of sialic acid receptors and influenza A virus of avian and swine origin in experimentally infected pigs

Virology Journal — Thu, 08 Sep 2011 04:00:00 +0100

Conclusions: A difference in predilection sites between SIV and AIV virus was found, and this difference was in accordance with the distribution of the SA-alpha-2,6 and SA-alpha-2,3 receptor, respectively. The results indicated that the distribution of influenza A virus receptors in pigs are similar to that of humans and therefore challenge the theory that the pig acts as a mixing vessel between human and avian influenza viruses. Furthermore, it was shown that AIV prefers to infect alveolar type II epithelial cells in pigs. This corresponds with findings in humans emphasising the resemblance between the two species. (Source: Virology Journal)

PrePrint: Reassortment Networks and the Evolution of Pandemic H1N1 Swine-Origin Influenza

IEEE/ACM Transactions on Computational Biology and Bioinformatics — Sun, 04 Sep 2011 04:30:47 +0100

We report their application to the swine-origin pandemic H1N1 virus (S-OIV). A database of all influenza A viruses for which complete genome sequences were available in Genbank by October 2009 was created and dynamic programming was used to compute distances between all corresponding segments. A reassortment network was created to obtain the minimum cost evolutionary paths from all viruses to the exemplar S-OIV A/California/04/2009. This analysis took 35 hours on the Cray Extreme Multithreading (XMT) supercomputer, which has special hardware to permit efficient parallelization. Six specific H1N1/H1N2 bottleneck viruses were identified that almost always lie on minimum cost paths to S-OIV. We conjecture that these viruses are crucial to S-OIV evolution and worthy of careful study from a mol...

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Hemagglutinin-neuraminidase balance confers respiratory-droplet transmissibility of the pandemic H1N1 influenza virus in ferrets [Microbiology]

Proceedings of the National Academy of Sciences — Mon, 22 Aug 2011 23:00:00 +0100

A novel reassortant derived from North American triple-reassortant (TRsw) and Eurasian swine (EAsw) influenza viruses acquired sustained human-to-human transmissibility and caused the 2009 influenza pandemic. To identify molecular determinants that allowed efficient transmission of the pandemic H1N1 virus among humans, we evaluated the direct-contact and respiratory-droplet transmissibility in ferrets of representative swine influenza viruses of different lineages obtained through a 13-y surveillance program in southern China. Whereas all viruses studied were transmitted by direct contact with varying efficiency, respiratory-droplet transmissibility (albeit inefficient) was observed only in the TRsw-like A/swine/Hong Kong/915/04 (sw915) (H1N2) virus. The sw915 virus had acquired the M gene...

Characterization of Influenza A Outbreaks in Minnesota Swine Herds and Measures Taken to Reduce the Risk of Zoonotic Transmission

Zoonoses and Public Health — Wed, 20 Jul 2011 18:53:27 +0100

SummaryInfluenza A virus infections commonly cause respiratory disease in swine and can be transmitted between people and pigs, with potentially novel strains introduced into herds and spilling back into the human population. The goals of this study were to characterize influenza infections in Minnesota pigs and assess biosecurity measures used by swine workers. Veterinarians submitting influenza‐positive swine samples to the University of Minnesota Veterinary Diagnostic Laboratory between October 2007 and April 2009 were surveyed regarding disease‐related information and biosecurity procedures at each farm. Influenza‐positive samples were submitted year‐round, peaking in spring and fall. H1N1 was the most commonly detected subtype (56%), followed by H3N2 (14%) and H1N2 (12%). Most...

Neuraminidase inhibitor susceptibility of swine influenza A viruses isolated in Germany between 1981 and 2008

Medical Microbiology and Immunology — Tue, 21 Jun 2011 18:00:24 +0100

Abstract European swine influenza A viruses donated the matrix protein 2 as well as the neuraminidase (NA) gene to pandemic influenza A (H1N1) viruses that emerged in 2009. As a result, the latter became amantadine resistant and neuraminidase inhibitor (NAI) susceptible. These recent developments reflecting the close connection between influenza A virus infection chains in humans and pigs urge an antiviral surveillance within swine influenza A viruses. Here, NAI susceptibility of 204 serologically typed swine influenza A viruses of subtypes H1N1, H1N2, and H3N2 circulating in Germany between 1981 and 2008 was analyzed in chemiluminescence-based NA inhibition assays. Mean 50% inhibitory concentrations of oseltamivir and zanamivir indicate a good drug susceptibility of teste...

Expression of myeloperoxidase in swine influenza virus (SIV)-infected neutrophils in lungs from pigs experimentally infected with SIV subtype H1N2

Veterinary Research Communications — Mon, 20 Jun 2011 14:21:50 +0100

Abstract The expression of myeloperoxidase (MPO) was examined in the swine influenza virus (SIV)-infected neutrophils in the lungs of pigs experimentally infected with swine influenza virus (SIV) subtype H1N2 by immunohistochemistry. Five pigs each from the infected and non-infected group were euthanized 1, 3, 5, 7, and 10 days post-inoculation (dpi). Immunohistochemical reactivity was mainly seen in neutrophils. The score for pulmonary histopathological lesions correlated with the score for MPO immunohistochemical reactivity (r s = 0.962, P < 0.01). In addition, the score for in situ hybridization of SIV nucleic acid correlated with the score for MPO immunohistochemical reactivity (r s = 0.976, P < 0.01). These results suggest neutrophi...

PrePrint: Reassortment Networks and the Evolution of Pandemic H1N1 Swine-Origin Influenza

IEEE/ACM Transactions on Computational Biology and Bioinformatics — Thu, 09 Jun 2011 00:01:45 +0100

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Novel Swine H1N2 In Indiana With Pandemic H1N1 Genes

Recombinomics — Wed, 09 Mar 2011 17:34:22 +0100

The commentary discusses the novel swine H1N2 in Indiana with pandemic internal genes. (03/08/11 21:20) (Source: Recombinomics)

Novel Swine H1N2 In North Carolina With Pandemic H1N1 Genes

Recombinomics — Wed, 09 Mar 2011 17:34:22 +0100

The commentary discusses the novel swine H1N2 in North Carolina with pandemic internal genes. (03/07/11 23:50) (Source: Recombinomics)

Novel Swine H1N2 In England With Pandemic H1N1 Genes

Recombinomics — Wed, 09 Mar 2011 17:34:22 +0100

The commentary discusses the novel swine H1N2 in England with pandemic internal genes. (03/07/11 23:00) (Source: Recombinomics)

Enhanced pneumonia and disease in pigs vaccinated with an inactivated human-like (δ-cluster) H1N2 vaccine and challenged with pandemic 2009 H1N1 influenza virus.

Vaccine — Mon, 07 Feb 2011 00:00:00 +0100

This report describes a vaccine-heterologous challenge model in which pigs were administered an inactivated H1N2 vaccine with a human-like (δ-cluster) H1 six and three weeks before challenge with H1 homosubtypic, heterologous 2009 pandemic H1N1. At necropsy, macroscopic and microscopic pneumonia scores were significantly higher in the vaccinated and challenged (Vx/Ch) group compared to non-vaccinated and challenged (NVx/Ch) pigs. The Vx/Ch group also demonstrated enhanced clinical disease and a significantly elevated pro-inflammatory cytokine profile in bronchoalveolar lavage fluid compared to the NVx/Ch group. In contrast, viral shedding and replication were significantly higher in NVx/Ch pigs although all challenged pigs, including Vx/Ch pigs, were shedding virus in nasal secretions. He...

Comparison of two H1N2 swine influenza A viruses from disease outbreaks in pigs in Sweden during 2009 and 2010

Virus Genes — Fri, 21 Jan 2011 15:23:16 +0100

Abstract The influenza A virus subtypes H1N1, H1N2 and H3N2 are prevalent in pig populations worldwide. In the present study, two relatively uncommon swine influenza virus (SIV) H1N2 subtypes, isolated in Sweden in 2009 and 2010, were compared regarding their molecular composition and biological characteristics. The differences regarding markers purportedly related to pathogenicity, host adaptation or replication efficiency. They included a truncated PB1-F2 protein in the earlier isolate but a full length version in the more recent one; differences in the number of haemagglutinin glycosylation sites, including a characteristic human one; and a nuclear export protein with altered export signal. Of particular interest, the NS1 amino acid sequence of swine H1N2-2009 and 2010 ...

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Swine influenza viruses isolated in 1983, 2002 and 2009 in Sweden exemplify different lineages

Acta Veterinaria Scandinavica — Tue, 14 Dec 2010 00:00:00 +0100

Swine influenza virus isolates originating from outbreaks in Sweden from 1983, 2002 and 2009 were subjected to nucleotide sequencing and phylogenetic analysis. The aim of the studies was to obtain an overview on their potential relatedness as well as to provide data for broader scale studies on swine influenza epidemiology. Nonetheless, analyzing archive isolates is justified by the efforts directed to the comprehension of the appearance of pandemic H1N1 influenza virus. Interestingly, this study illustrates the evolution of swine influenza viruses in Europe, because the earliest isolate belonged to 'classical' swine H1N1, the subsequent ones to Eurasian 'avian-like' swine H1N1 and reassortant avian-like swine H1N2 lineages, respectively. The latter two showed close genetic relatedness reg...

Singleplex real-time RT-PCR for detection of influenza A virus and simultaneous differentiation of A/H1N1v and evaluation of the RealStar influenza kit

Journal of Clinical Virology — Mon, 15 Nov 2010 00:00:00 +0100

Conclusion: Both assays demonstrated high sensitivity and specificity and might assist in the diagnosis of suspected influenza cases. (Source: Journal of Clinical Virology)

Envelope Proteins Pertain with Evolution and Adaptive Mechanism of the Novel Influenza A/H1N1 in Humans.

Journal of Microbiology and Biotechnology — Mon, 01 Nov 2010 00:00:00 +0100

This study further suggests that the adaptive capability of the S-OIV in human is acquired by the unique mutations generated during emergence. PMID: 21124053 [PubMed - in process] (Source: Journal of Microbiology and Biotechnology)

H1N1/N2 Swine/Human Reassortants Raise Pandemic Concerns

Recombinomics — Sun, 31 Oct 2010 10:25:06 +0100

The commentary discusses the pandemic potential of H1N1 and H1N2 reassortants with seasonal H and N genes from 2003 (10/31/10 02:45) (Source: Recombinomics)

H1N1/N2 Swine/Human Reassortants in Argentina

Recombinomics — Fri, 29 Oct 2010 18:31:15 +0100

The commentary discusses the detection of pandemic H1N1 and H1N2 reassortants with seasonal H and N genes from 2003 (10/29/10 11:17) (Source: Recombinomics)

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Prevalence of antibodies to swine influenza viruses in humans with occupational exposure to pigs, Thuringia, Germany, 2008-2009

Journal of Medical Virology — Wed, 14 Jul 2010 23:00:00 +0100

The Eurasian lineages of swine influenza viruses are different genetically from classical swine H1N1 influenza viruses and comprise avian-like H1N1 and human-like H1N2 and H3N2 subtypes. Although sporadic isolation of such viruses from human specimens has been reported, the prevalence of human infections is not known. In the present study, the seroprevalence against Eurasian swine influenza viruses was investigated. Sera were collected in Thuringia, Germany, from December 2007 to April 2009. The study group comprised 118 professionals with occupational exposure to pigs (50 pig slaughterers/meat inspectors, 46 pig farmers, 22 veterinarians caring for pig herds). The control group included 118 age- and gender-matched blood donors from Thuringia. As a result, 18 sera of the study group were i...

Novel Swine influenza virus reassortants in pigs, china.

Emerging Infectious Diseases — Wed, 30 Jun 2010 23:00:00 +0100

Authors: Bi Y, Fu G, Chen J, Peng J, Sun Y, Wang J, Pu J, Zhang Y, Gao H, Ma G, Tian F, Brown IH, Liu J During swine influenza virus surveillance in pigs in China during 2006-2009, we isolated subtypes H1N1, H1N2, and H3N2 and found novel reassortment between contemporary swine and avian panzootic viruses. These reassortment events raise concern about generation of novel viruses in pigs, which could have pandemic potential. PMID: 20587196 [PubMed - in process] (Source: Emerging Infectious Diseases)

Swine influenza vaccines: current status and future perspectives.

Animal Health Research Reviews — Wed, 12 May 2010 23:00:00 +0100

Authors: Ma W, Richt JA Swine influenza is an important contagious disease in pigs caused by influenza A viruses. Although only three subtypes of influenza A viruses, H1N1, H1N2 and H3N2, predominantly infect pigs worldwide, it is still a big challenge for vaccine manufacturers to produce efficacious vaccines for the prevention and control of swine influenza. Swine influenza viruses not only cause significant economic losses for the swine industry, but are also important zoonotic pathogens. Vaccination is still one of the most important and effective strategies to prevent and control influenza for both the animal and human population. In this review, we will discuss the current status of swine influenza worldwide as well as current and future options to control this economically import...

Pandemic flu, like seasonal H1N1, shows signs of resisting Tamiflu

ScienceDaily Headlines — Tue, 02 Mar 2010 16:00:00 +0100

If the behavior of the seasonal form of the H1N1 influenza virus is any indication, scientists say that chances are good that most strains of the pandemic H1N1 flu virus will become resistant to Tamiflu, the main drug stockpiled for use against it. Researchers have traced the evolutionary history of the seasonal H1N1 influenza virus, which first infected humans during the 1918 pandemic. It is one of three seasonal influenza A viruses that commonly infect humans. The others are H1N2 and H3N2. (Source: ScienceDaily Headlines)

Pandemic Flu, Like Seasonal H1N1, Shows Signs Of Resisting Tamiflu

Health News from Medical News Today — Tue, 02 Mar 2010 08:00:00 +0100

If the behavior of the seasonal form of the H1N1 influenza virus is any indication, scientists say that chances are good that most strains of the pandemic H1N1 flu virus will become resistant to Tamiflu, the main drug stockpiled for use against it. Researchers at Ohio State University have traced the evolutionary history of the seasonal H1N1 influenza virus, which first infected humans during the 1918 pandemic. It is one of three seasonal influenza A viruses that commonly infect humans. The others are H1N2 and H3N2... (Source: Health News from Medical News Today)

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Pandemic flu, like seasonal H1N1, shows signs of resisting Tamiflu

EurekAlert! - Medicine and Health — Mon, 01 Mar 2010 05:00:00 +0100

(Ohio State University) If the behavior of the seasonal form of the H1N1 influenza virus is any indication, scientists say that chances are good that most strains of the pandemic H1N1 flu virus will become resistant to Tamiflu, the main drug stockpiled for use against it. Researchers have traced the evolutionary history of the seasonal H1N1 influenza virus, which first infected humans during the 1918 pandemic. It is one of three seasonal influenza A viruses that commonly infect humans. The others are H1N2 and H3N2. (Source: EurekAlert! - Medicine and Health)

Experimental inoculation of pigs with pandemic H1N1 2009 virus and HI cross-reactivity with contemporary swine influenza virus antisera

Influenza and Other Respiratory Viruses — Tue, 12 Jan 2010 00:00:00 +0100

Conclusions In experiment 1, all inoculated pigs demonstrated clinical signs and lesions similar to those induced by endemic SIV. Viable virus and antigen were only detected in the respiratory tract. In experiment 2, serologic cross-reactivity was limited against H1N1 2009 isolates, notably among virus antisera from the same HA phylogenetic cluster. The limited cross-reactivity suggests North American pigs may not be fully protected against H1N1 2009 from previous exposure or vaccination and novel tests are needed to rapidly diagnose the introduction of H1N1 2009. In experiment 3, an RT[ndash]PCR test that discriminates between H1N1 2009 and endemic North American SIV was developed and validated on clinical samples. (Source: Influenza and Other Respiratory Viruses)

Virological Surveillance and Preliminary Antigenic Characterization of Influenza Viruses in Pigs in Five European Countries from 2006 to 2008

Zoonoses and Public Health — Wed, 23 Dec 2009 00:00:00 +0100

This study presents the results of the virological surveillance for swine influenza viruses (SIVs) in Belgium, UK, Italy, France and Spain from 2006 to 2008. Our major aims were to clarify the occurrence of the three SIV subtypes [ndash] H1N1, H3N2 and H1N2 [ndash] at regional levels, to identify novel reassortant viruses and to antigenically compare SIVs with human H1N1 and H3N2 influenza viruses. Lung tissue and/or nasal swabs from outbreaks of acute respiratory disease in pigs were investigated by virus isolation. The hemagglutinin (HA) and neuraminidase (NA) subtypes were determined using standard methods. Of the total 169 viruses, 81 were classified as 'avian-like' H1N1, 36 as human-like H3N2 and 47 as human-like H1N2. Only five novel reassortant viruses were identified: two H1N1 viru...

From where did the 2009 'swine-origin' influenza A virus (H1N1) emerge?

Virology Journal — Tue, 24 Nov 2009 00:00:00 +0100

The swine-origin influenza A (H1N1) virus that appeared in 2009 and was first found in human beings in Mexico, is a reassortant with at least three parents. Six of the genes are closest in sequence to those of H1N2 'triple-reassortant' influenza viruses isolated from pigs in North America around 1999-2000. Its other two genes are from different Eurasian 'avian-like' viruses of pigs; the NA gene is closest to H1N1 viruses isolated in Europe in 1991-1993, and the MP gene is closest to H3N2 viruses isolated in Asia in 1999-2000. The sequences of these genes do not directly reveal the immediate source of the virus as the closest were from isolates collected more than a decade before the human pandemic started. The three parents of the virus may have been assembled in one place by natural means...

The first Swedish H1N2 swine influenza virus isolate represents an uncommon reassortant

BioMed Central — Wed, 28 Oct 2009 00:00:00 +0100

The European swine influenza viruses (SIVs) show considerable diversity comprising different types of H1N1, H3N2, and H1N2 strains. The intensifying full genome sequencing efforts reveal further reassortants within these subtypes. Here we report the identification of an uncommon reassortant variant of H1N2 subtype influenza virus isolated from a pig in a multisite herd where H1N2 swine influenza was diagnosed for the first time in Sweden during the winter of 2008- 2009. The majority of the European H1N2 swine influenza viruses described so far possess haemagglutinin (HA) of the human-like H1N2 SIV viruses and the neuraminidase (NA) of either the European H1N2 or H3N2 SIV-like viruses. The Swedish isolate has an avian-like SIV HA and a H3N2 SIV-like NA, which is phylogenetically more closel...

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Comparison of the usefulness of the CACO-2 cell line with standard substrates for isolation of swine influenza A viruses.

Journal of Virological Methods — Mon, 21 Sep 2009 23:00:00 +0100

Authors: Chiapponi C, Zanni I, Garbarino C, Barigazzi G, Foni E Influenza A virus isolation is undertaken routinely in embryonated chicken eggs, but to improve virus detection various cell lines can be used. The CACO-2 cell line was compared to the MDCK cell line and embryonated chicken eggs for the isolation of H1N1, H1N2, H3N2 swine influenza A virus subtypes from clinical specimens. From 2006 to 2008, 104 influenza A samples found positive by PCR from 42 respiratory outbreaks in Italian swine farms were examined by virus isolation. Sixty swine influenza A viruses were isolated (16 H1N1, 28 H1N2, 16 H3N2) and their growth behaviour on the different substrates was examined. 16/16 H1N1, 28/28 H1N2 and 8/16 of H3N2 viruses were isolated from the CACO-2 cell line, while 7/16 H1N1, 3/28 H...

Detection of influenza A(H1N1)v virus by real-time RT-PCR.

Euro Surveill — Sat, 19 Sep 2009 02:34:02 +0100

Authors: Panning M, Eickmann M, Landt O, Monazahian M, Olschläger S, Baumgarte S, Reischl U, Wenzel JJ, Niller HH, Günther S, Hollmann B, Huzly D, Drexler JF, Helmer A, Becker S, Matz B, Eis-Hübinger A, Drosten C Influenza A(H1N1)v virus was first identified in April 2009. A novel real-time RT-PCR for influenza A(H1N1)v virus was set up ad hoc and validated following industry-standard criteria. The lower limit of detection of the assay was 384 copies of viral RNA per ml of viral transport medium (95% confidence interval: 273-876 RNA copies/ml). Specificity was 100% as assessed on a panel of reference samples including seasonal human influenza A virus H1N1 and H3N2, highly pathogenic avian influenza A virus H5N1 and porcine influenza A virus H1N1, H1N2 and H3N2 samples. T...

Detection of Influenza A(H1N1)v virus by real-time RT-PCR

Eurosurveillance latest news — Thu, 10 Sep 2009 00:00:00 +0100

Influenza A(H1N1)v virus was first identified in April 2009. A novel real-time RT-PCR for influenza A(H1N1)v virus was set up ad hoc and validated following industry-standard criteria. The lower limit of detection of the assay was 384 copies of viral RNA per ml of viral transport medium (95% confidence interval: 273-876 RNA copies/ml). Specificity was 100% as assessed on a panel of reference samples including seasonal human influenza A virus H1N1 and H3N2, highly pathogenic avian influenza A virus H5N1 and porcine influenza A virus H1N1, H1N2 and H3N2 samples. The real-time RT-PCR assay for the influenza A matrix gene recommended in 2007 by the World Health Organization was modified to work under the same reaction conditions as the influenza A(H1N1)v virus-specific test. Both assays were e...

Detection and subtyping of influenza A virus based on a short oligonucleotide microarray

Diagnostic Microbiology and Infectious Disease — Sun, 06 Sep 2009 23:00:00 +0100

We report the design and characterization of a microarray with 46 short virus-specific oligonucleotides for detecting influenza A virus of 5 subtypes: H1N1, H1N2, H3N2, H5N1, and H9N2. A unique combination of 3 specific modifications was introduced into the microarray assay: (1) short probes of 19 to 27 nucleotides, (2) simple amplification of full-length hemagglutinin and neuraminidase cDNAs with universal primers, and (3) Klenow-mediated labeling and further amplification of the samples before hybridization. The assay correctly and specifically detected and subtyped 11 different influenza A isolates from human, avian, and swine species representing the 5 subtypes. When tested with 225 clinical samples, 20 were detected to be positive using our microarray-based assay, whereas only 10 were...

Cluster analysis of the origins of the new influenza A(H1N1) virus.

Euro Surveill — Thu, 20 Aug 2009 17:20:04 +0100

Authors: Solovyov A, Palacios G, Briese T, Lipkin WI, Rabadan R In March and April 2009, a new strain of influenza A(H1N1) virus has been isolated in Mexico and the United States. Since the initial reports more than 10,000 cases have been reported to the World Health Organization, all around the world. Several hundred isolates have already been sequenced and deposited in public databases. We have studied the genetics of the new strain and identified its closest relatives through a cluster analysis approach. We show that the new virus combines genetic information related to different swine influenza viruses. Segments PB2, PB1, PA, HA, NP and NS are related to swine H1N2 and H3N2 influenza viruses isolated in North America. Segments NA and M are related to swine influenza viruses isolate...

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Isolation and genetic characterization of avian-like H1N1 and novel ressortant H1N2 influenza viruses from pigs in China.

Biochemical and Biophysical Research communications — Tue, 28 Jul 2009 16:27:16 +0100

In this study, we reported avian-like H1N1 and novel ressortant H1N2 influenza viruses from pigs in China. Homology and phylogenetic analyses showed that the H1N1 virus (A/swine/Zhejiang/1/07) was closely to avian-like H1N1 viruses and seemed to be derived from the European swine H1N1 viruses, which was for the first time reported in China; and the two H1N2 viruses (A/swine/Shanghai/1/07 and A/swine/Guangxi/13/06) were novel ressortant H1N2 influenza viruses containing genes from the classical swine (HA, NP, M and NS), human (NA and PB1) and avian (PB2 and PA) lineages, which indicted that the reassortment among human, avian, and swine influenza viruses had taken place in pigs in China and resulted in the generation of new viruses. The isolation of avian-like H1N1 influenza virus originate...

Two genotypes of H1N2 swine influenza viruses appeared among pigs in China

Journal of Clinical Virology — Sun, 26 Jul 2009 23:00:00 +0100

Conclusion: Two different genotypes of H1N2 appeared among pigs in China. A/swine/Guangdong/1/06 was probably from H1N2 swine influenza viruses of North America; while A/swine/Tianjin/1/04 maybe come from reassortments of classical H1N1 swine and H3N2 human viruses prevalent in North America. (Source: Journal of Clinical Virology)

Characterization of a newly emerged genetic cluster of H1N1 and H1N2 swine influenza virus in the United States

Virus Genes — Tue, 14 Jul 2009 11:15:05 +0100

This study indicates that the human-like H1 SIV can efficiently replicate and transmit in the swine host and now co-circulates with contemporary SIVs as a distinct genetic cluster of H1 SIV. Content Type Journal ArticleDOI 10.1007/s11262-009-0386-6Authors Amy L. Vincent, National Animal Disease Center, USDA-ARS Virus and Prion Diseases of Livestock Research Unit 2300 Dayton Road Ames IA 50010 USAWenjun Ma, National Animal Disease Center, USDA-ARS Virus and Prion Diseases of Livestock Research Unit 2300 Dayton Road Ames IA 50010 USAKelly M. Lager, National Animal Disease Center, USDA-ARS Virus and Prion Diseases of Livestock Research Unit 2300 Dayton Road Ames IA 50010 USAMarie R. Gramer, University of Minnesota Minnesota Veterinary Diagnostic Laboratory St. Paul MN USAJuergen A. Rich...

Emergence of a novel swine-origin influenza A virus (S-OIV) H1N1 virus in humans

Journal of Clinical Virology — Sun, 21 Jun 2009 23:00:00 +0100

Abstract: A recently emerged novel influenza A H1N1 virus continues to spread globally. The virus contains a novel constellation of gene segments, the nearest known precursors being viruses found in swine and it likely arose through reassortment of two or more viruses of swine origin. H1N1, H1N2 and H3N2 subtype swine influenza viruses have occasionally infected humans before but such zoonotic transmission events did not lead to sustained human-to-human transmission in the manner this swine-origin influenza virus (S-OIV) has done. Its transmission among humans appears to be higher than that observed with seasonal influenza. Children and young adults appear to those most affected and also those who appear to maintain transmission. Clinical disease generally appears mild but complications le...

Pathogenesis and Subsequent Cross-Protection of Influenza Virus Infection in Pigs Sustained by an H1N2 Strain

Zoonoses and Public Health — Tue, 16 Jun 2009 23:00:00 +0100

The objectives of this study were to investigate the pathogenesis of Sw/Italy/1521/98 (H1N2) influenza virus, isolated from respiratory tissues of pigs from herds in Northern Italy, and to evaluate its potential cross-protection against the Sw/Fin/2899/82 (H1N1) strain. In the pathogenesis test, eight pigs were intranasally infected with H1N2 virus; at pre-determined intervals, these animals were killed and necropsied, along with eight uninfected animals. In the cross-protection test, sixteen pigs were infected by intranasal (i.n.) and intratracheal (i.t.) routes with either H1N2 or H1N1 virus. Twenty days later, all pigs were challenged (by the same route), with either the homologous H1N2 or heterologous H1N1 virus strains. Control group was inoculated with culture medium alone. On post-c...

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Genetic and Antigenic Evolution of Swine Influenza Viruses in Europe and Evaluation of Their Zoonotic Potential

Zoonoses and Public Health — Thu, 28 May 2009 04:00:00 +0100

Swine influenza is a highly contagious respiratory viral infection of pigs that has become enzootic in areas densely populated with pigs. Like other influenza A viruses, swine influenza virus (SIV) is genetically unstable and able to accumulate antigenic drifts and/or antigenic shifts. The pig is susceptible to both avian and human influenza viruses and can serve as an intermediate host in influenza virus ecology. Zoonotic agents may emerge in pigs following the modification of an established swine strain, adaptation of a strain of avian origin to the mammalian host, or reassortment between human and avian influenza viruses. Three different subtypes, H1N1, H3N2 and H1N2, are at present circulating in Europe. They differ from those found in North America and Asia and various lineages can be...

Cluster analysis of the origins of the new influenza A(H1N1) virus

Eurosurveillance latest news — Thu, 28 May 2009 00:00:00 +0100

In March and April 2009, a new strain of influenza A(H1N1) virus has been isolated in Mexico and the United States. Since the initial reports more than 10,000 cases have been reported to the World Health Organization, all around the world. Several hundred isolates have already been sequenced and deposited in public databases. We have studied the genetics of the new strain and identified its closest relatives through a cluster analysis approach. We show that the new virus combines genetic information related to different swine influenza viruses. Segments PB2, PB1, PA, HA, NP and NS are related to swine H1N2 and H3N2 influenza viruses isolated in North America. Segments NA and M are related to swine influenza viruses isolated in Eurasia. (Source: Eurosurveillance latest news)

Nigeria: Swine Flu - How Ready are Citizens?

AllAfrica News: Health and Medicine — Mon, 25 May 2009 09:58:43 +0100

Swine flu, according to a public health specialist, Dr. Ibrahim Dalhatu, is an influenza caused by strains of influenza virus referred to as swine influenza virus (SIV). It usually infects pigs. Presently, these strains are all found in Influenza C virus and the subtypes of Influenza A virus known as H1N1, H1N2, H3N1, H3N2 and H2N3." (Source: AllAfrica News: Health and Medicine)

6,552 Confirmed Swine Flu Cases And 9 Deaths In The USA

Health News from Medical News Today — Sat, 23 May 2009 08:00:00 +0100

The Centers for Disease Control and Prevention (CDC) announced at the end of the day of 22nd May, 2009, that so far 6,552 humans have been infected with the A(H1N1) influenza virus, also known as swine flu. This new A (H1N2) flu virus originates from pigs and was first identified in April this year. (Source: Health News from Medical News Today)

Different neuraminidase inhibitor susceptibilities of human H1N1, H1N2, and H3N2 influenza A viruses isolated in Germany from 2001 to 2005/2006.

Antiviral Research — Wed, 01 Apr 2009 04:00:00 +0100

Authors: Bauer K, Richter M, Wutzler P, Schmidtke M In the flu season 2005/2006 amantadine-resistant human influenza A viruses (FLUAV) of subtype H3N2 circulated in Germany. This raises questions on the neuraminidase inhibitor (NAI) susceptibility of FLUAV. To get an answer, chemiluminescence-based neuraminidase inhibition assays were performed with 51 H1N1, H1N2, and H3N2 FLUAV isolated in Germany from 2001 to 2005/2006. According to the mean IC(50) values (0.38-0.91 nM for oseltamivir and 0.76-1.13 nM for zanamivir) most H1N1 and H3N2 FLUAV were NAI-susceptible. But, about four times higher zanamivir concentrations were necessary to inhibit neuraminidase activity of H1N2 viruses. Two H1N1 isolates were less susceptible to both drugs in NA inhibition as well as virus yield reduction a...

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A human case of swine influenza virus infection in Europe--implications for human health and research.

Euro Surveill — Thu, 26 Feb 2009 12:12:25 +0100

Authors: Van Reeth K, Nicoll A Swine are susceptible to the same influenza A virus subtypes as humans--H1N1, H3N2 and H1N2--and the histories of influenza in pigs and people are closely linked. Many swine influenza viruses are a result of reassortment and their genes are composed of human and avian and/or swine virus genes. Indeed, it is known that both human and avian influenza viruses occasionally transmit to pigs, and that pigs can serve as "mixing vessels" for these viruses, meaning that viruses can exchange genetic material and lead to the production of a new "hybrid" virus. This has led to the thinking that perhaps pandemic viruses could emerge following reassortment in pigs. However, since nobody has observed the start of a pandemic, there remains no direct evidence to make this...

Ongoing evolution of swine influenza viruses: a novel reassortant

Archives of Virology — Thu, 06 Nov 2008 00:37:04 +0100

Abstract A novel H3N2 influenza virus strain isolated in Germany from pigs with clinical symptoms of influenza is described. It was characterised by neutralisation test, hemagglutination inhibition test and complete sequencing of the genome. The data demonstrate the emergence of a H3N2 reassortant with the human-like HAH3 gene of prevalent European porcine H3N2 influenza viruses and a NAN2 gene of the European porcine H1N2 viruses. The gene segments of the internal proteins are avian-like, consistent with European porcine influenza viruses. Analysis of GenBank sequence data reveals numerous reassortment events in recent years, demonstrating ongoing evolution of swine influenza viruses. Content Type Journal ArticleCategory Original ArticleDOI 10.1007/s00705-008-0244-1Auth...

Prevalence of avian influenza viruses, Borrelia garinii, Mycobacterium avium, and Mycobacterium avium subsp. paratuberculosis in waterfowl and terrestrial birds in Slovakia, 2006.

Avian Pathology — Thu, 18 Sep 2008 17:52:35 +0100

Authors: Gronesova P, Ficova M, Mizakova A, Kabat P, Trnka A, Betakova T The prevalence of Borrelia, Mycobacteria and avian influenza virus (AIV) infections, together with the distribution of different AIV subtypes, was studied in migratory waterfowl and terrestrial birds trapped in three localities in Slovakia during 2006. Samples obtained from waterfowl captured in the Senianske Ponds area of Eastern Slovakia showed the highest diversity of AIV isolates. A total of 13 different subtypes were detected in 19 samples from this location (H1N2, H2N2, H3N2, H6N6, H7N6, H9N2, H9N5, H9N6, H10N5, H10N6, H12N6, H13N6, and H16N6). H3N5 virus was detected in 50% of passerines testing positive for AIV in the Parizske Wetlands, with H7N2, H9N2, H9N5, H12N1, and H13N2 infections also recorded at th...

Seroprevalence and genetic evolutions of swine influenza viruses under vaccination pressure in Korean swine herds.

Virus Research — Wed, 10 Sep 2008 04:00:00 +0100

Authors: Pascua PN, Song MS, Lee JH, Choi HW, Han JH, Kim JH, Yoo GJ, Kim CJ, Choi YK An overall 8427 total of blood samples collected from growing to finishing pigs were submitted for diagnosis of swine influenza virus infection between January 2002 and December 2006. Sera from 2002 to 2005 were examined for antibodies against four different swine influenza subtypes using the hemagglutination inhibition test to investigate seroprevalence rates by natural infection in Korean swine herds while nasal swabs and lung tissue samples were used for viral isolation. The natural infection rate of subtypes H1, H3, and the dual positive were 41.5%, 3.6%, and 0.9%, respectively. Of the 660 swine nasal swab specimens collected from pigs with respiratory diseases, forty swine influenza viruses were ...

[Molecular analyses of human influenza viruses. Circulation of new variants since 1995/96.]

Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz — Sat, 06 Sep 2008 15:45:47 +0100

Authors: Biere B, Schweiger B The evolution of influenza viruses is increasingly pursued by molecular analyses that complement classical methods. The analyses focus on the two surface proteins hemagglutinin (HA) and neuraminidase (NA) which determine the viral antigenic profile. Influenza A(H3N2) viruses are exceptionally variable, so that usually at least two virus variants cocirculate at the same time. Together with influenza B viruses they caused approximately 90% of influenza virus infections in Germany during the last 12 seasons, while influenza A(H1N1) viruses only played a subordinate part. Unexpectedly, reassorted viruses of subtype A(H1N2) appeared during the seasons 2001/02 and 2002/03, but were isolated only rarely and gained no epidemiological significance. Furthermore, dur...

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Phylogenetic analysis of swine influenza viruses recently isolated in Korea

Virus Genes — Tue, 24 Jun 2008 06:02:34 +0100

Abstract Several influenza A viral subtypes were isolated from pigs during a severe outbreak of respiratory disease in Korea during 2005 and 2006. They included a classical swine H1N1 subtype, two swine-human-avian triple-recombinant H1N2 subtypes, and a swine-human-avian triple-recombinant H3N2 subtype. In the current study, genetic characterization to determine the probable origin of these recent isolates was carried out for the first time. Phylogenetic analysis indicated that all the recent Korean isolates of H1N1, H1N2, and H3N2 influenza are closely related to viruses from the United States. Serologic and genetic analysis indicated that the Korean H1N2 viral subtypes were introduced directly from the United States, and did not arise from recombination between Korean H...

Seroprevalence of H1N1, H3N2 and H1N2 Influenza Viruses in Pigs in Seven European Countries in 2002-2003

Medscape Pulmonary Medicine Headlines — Wed, 18 Jun 2008 15:13:05 +0100

The seroprevalence of the H1N1, H3N2, and H1N2 influenza virus in pigs throughout different European regions were determined. Influenza and Other Respiratory Viruses (Source: Medscape Pulmonary Medicine Headlines)

Surveillance of avian and swine influenza in the swine population in Taiwan, 2004.

Journal of Microbiology, Immunology, and Infection — Sun, 01 Jun 2008 04:00:00 +0100

CONCLUSIONS: Different subtypes of SIV co-circulate among swine from different farms within the same county and may cause clinical outbreaks of the disease in Taiwan. PMID: 18629419 [PubMed - in process] (Source: Journal of Microbiology, Immunology, and Infection)

One-step multiplex RT-PCR for detection and subtyping of swine influenza H1, H3, N1, N2 viruses in clinical samples using a dual priming oligonucleotide (DPO) system.

Journal of Virological Methods — Fri, 16 May 2008 04:00:00 +0100

Authors: Lee CS, Kang BK, Lee DH, Lyou SH, Park BK, Ann SK, Jung K, Song DS The swine influenza virus (SIV) H1N1, H1N2, and H3N2 subtypes circulate in Korean farm. A novel multiplex RT-PCR (m-RT-PCR) was developed to detect and subtype swine influenza viruses. This m-RT-PCR assay could identify H1, H3, N1 and N2 from clinical samples in single tube reaction using DPO system. Korean SIVs are closely related to the United States influenza viruses, and primers were developed for SIV from North American viruses and recently Korean isolates. The sensitivity of the m-RT-PCR was 10TCID(50)/ml for H1N1, H1N2 or H3N2. The lowest viral concentrations detected by single PCR were 1TCID(50)/ml for each subtype. Non-specific reactions were not observed when other viruses and bacteria were used to as...

Genetic characterization of H1N1, H1N2 and H3N2 swine influenza virus in Thailand

Archives of Virology — Tue, 06 May 2008 19:16:30 +0100

In this study, 12 SIV isolates from the central and eastern part of Thailand were subtyped and the molecular genetics of hemagglutinin and neuraminidase were elucidated. Three subtypes, H1N1, H1N2 and H3N2, are described. Phylogenetic analysis of the SIV hemagglutinin and neuraminidase genes shows individual clusters with swine, human or avian influenza virus at various global locations. Furthermore, amino acid substitutions were detected either at the receptor binding site or the antigenic sites of the hemagglutinin gene. Content Type Journal ArticleCategory Original ArticleDOI 10.1007/s00705-008-0097-7Authors Salin Chutinimitkul, Chulalongkorn University Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine Bangkok 10330 ThailandNattakarn Thipp...

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Flow cytometric monitoring of influenza A virus infection in MDCK cells during vaccine production

BMC Biotechnology - Latest articles — Wed, 30 Apr 2008 04:00:00 +0100

Conclusions: It is shown that flow cytometry is a sensitive and robust method for the monitoring of viral infection in fixed cells from bioreactor samples. Therefore, it is a valuable addition to other detection methods of influenza virus infection such as immunotitration and RNA hybridisation. Thousands of individual cells are measured per sample. Thus, the presented method is believed to be quite independent of the concentration of infected cells (multiplicity of infection and total cell concentration) in bioreactors. This allows to perform detailed studies on factors relevant for optimization of virus yields in cell cultures. The method could also be used for process characterisation and investigations concerning reproducibility in vaccine manufacturing. (Source: BMC Biotechnology - Lat...

The evolution of human influenza A viruses from 1999 to 2006 - a complete genome study

Virology Journal — Fri, 07 Mar 2008 05:00:00 +0100

Conclusions: The present study is the first to our knowledge to characterise the evolution of complete genomes of influenza A H3N2, H1N1 and H1N2 isolates from Europe over a time period of seven years from 1999 to 2006. More precise knowledge about the circulating strains may have implications for predicting the following season circulating viruses and thereby better matching the vaccine composition. (Source: Virology Journal)

Identification and characterization of a late AH1N2 human reassortant in France during the 2002-2003 influenza season.

Virus Research — Sun, 02 Dec 2007 05:00:00 +0100

Authors: Al Faress S, Ferraris O, Moules V, Valette M, Hay A, Lina B We have previously shown a clear differential genetic evolution of the hemagglutinin (HA) of human AH1N1 and AH1N2 viruses, isolated in southern France between 2001 and 2004. However, our analysis revealed that one single AH1N2 isolate, detected in 2003 (A/Lyon/0838/2003), had its HA clustering within the HAs of the AH1N1 subtypes. To determine if this virus was a new reassortant, the nucleotide sequences of its eight RNA gene segments were compared with those of five representative strains of the AH1N1, AH1N2 and AH3N2 viruses, isolated during the same time-period. According to the sequences obtained, the neuraminidase (NA) gene segment of the A/Lyon/0838/2003 (H1N2) virus was genetically closely related to those of ...

Evolutionary analyses of European H1N2 swine influenza A virus by placing timestamps on the multiple reassortment events.

Virus Research — Thu, 11 Oct 2007 04:00:00 +0100

In this study, we used both global and local molecular clock concepts in a maximum likelihood framework to extrapolate the times of origins of the genome segments in European H1N2 swine viruses, and deduced that novel neuraminidase, hemagglutinin and other internal protein genes were introduced to the European H1N2 lineage at the 1970s, early 1980s and late 1980s, respectively through reassortments. Furthermore, in light of the evolutionary timescale reconstructed for the H1N2 viruses, we argue that further reassortments, in addition to those responsible for the introductions of novel genome segments, might have also occurred among the viruses prior to the outbreaks arose in United Kingdom at 1994. Our results confirm that the viral genes of various origins have stably maintained in swine ...

Pathogenesis and inflammatory responses of swine H1N2 influenza viruses in pigs.

Virus Research — Sun, 17 Jun 2007 10:34:21 +0100

In this study, we wanted to know whether swine H1N2 influenza viruses circulating in Korean pigs would cause clinical signs in pigs when experimentally infected. When pigs were infected with swine H1N2 viruses isolated from Korean pigs, pigs suffered from severe clinical signs of coughing, nasal discharge, labored breathing, facial edema, anorexia, and diarrhea. When the level of cytokine induction was measured using lung tissues, pro-inflammatory cytokines such as TNF-alpha, IL-1, and IL-8 were induced higher in lungs of infected pigs than in lungs of uninfected pigs. However, no increased induction of the anti-inflammatory cytokines such as IL-4 and IL-10 was observed in lungs of infected pigs. These results suggest that the pathogenesis induced in pigs by H1N2 influenza viruses may be i...

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Genetic analysis of two influenza A (H1) swine viruses isolated from humans in Thailand and the Philippines

Virus Genes — Thu, 12 Apr 2007 06:58:37 +0100

Abstract Influenza viruses A/Philippines/341/2004 (H1N2) and A/Thailand/271/2005 (H1N1) were isolated from two males, with mild influenza providing evidence of sporadic human infection by contemporary swine influenza. Both viruses were antigenically and genetically distinct from influenza A (H1N1 and H1N2) viruses that have circulated in the human population. Genetic analysis of the haemagglutinin genes found these viruses to have the highest degree of similarity to the classical swine H1 viruses circulating in Asia and North America. The neuraminidase gene and the internal genes were found to be more closely related to viruses circulating in European swine, which appear to have undergone multiple reassorting events. Although transmission of swine influenza to humans appea...

Serological Profiles after Consecutive Experimental Infections of Pigs with European H1N1, H3N2, and H1N2 Swine Influenza Viruses

Viral Immunology — Wed, 20 Sep 2006 18:27:37 +0100

Viral Immunology Jun 2006, Vol. 19, No. 3: 373-382. (Source: Viral Immunology)

Amantadine Resistance among Porcine H1N1, H1N2, and H3N2 Influenza A Viruses Isolated in Germany between 1981 and 2001

Intervirology — Mon, 11 Sep 2006 14:56:04 +0100

Intervirology 2006;49:286-293 (DOI:10.1159/000094244) (Source: Intervirology)

Influenza Vaccine Immunogenicity in 6- to 23-Month-Old Children: Are Identical Antigens Necessary for Priming?

PEDIATRICS — Fri, 01 Sep 2006 06:00:00 +0100

CONCLUSIONS. Although the immune response to the identical A/H1N1 vaccine antigen was similar in both groups, priming with different A/H3N2 antigens and B antigens in the spring produced a lower immune response to both antigens than that shown in children who received 2 doses of the same vaccine in the fall. However, ~70% of children in the spring group had a protective response to the H3N2 antigen after 2 doses. Initiating influenza immunization in the spring was superior to 1 dose of trivalent inactivated influenza vaccine in the fall. The goal of delivering 2 doses of influenza vaccine a month apart to vaccine-naive children within the narrow flu vaccination season is a challenge not yet met; thus far, only about half of children aged 6 to 23 months of age are receiving influenza vaccin...