The Shandong Animal Disease Control Center

Jinan, China

The Shandong Animal Disease Control Center

Jinan, China
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Sun Y.,China Agricultural University | Sun S.,China Agricultural University | Ma J.,China Agricultural University | Tan Y.,China Agricultural University | And 7 more authors.
Virology | Year: 2013

Twelve avian-origin H3N2 influenza strains were isolated from dogs with signs of respiratory disease in northern CHN during 2009-2010. Phylogenetic analysis showed that eight gene segments of all the isolates had a close relationship with those of avian-origin H3N2 canine influenza viruses (CIVs) from South Korea and southern CHN. Genetic analysis indicated that these isolates had a PERQTR/G HA cleavage motif, which differed from the PEKQTR/G motif of canine viruses before 2007. Noteworthy, one of our isolates had an additional basic amino acid at position -3 of the HA cleavage site, with a sequence of PERRTR/G which might facilitate the HA cleavage. An insertion of two amino acids at positions 74-75 in the neuraminidase stalk were found in all H3N2 CIVs isolated since 2009. Our findings show the continued evolution of avian-origin H3N2 CIVs and emphasize the necessity of continued surveillance of influenza virus in dogs. © 2012 Elsevier Inc.


Sun Y.,China Agricultural University | Pu J.,China Agricultural University | Fan L.,China Agricultural University | Sun H.,China Agricultural University | And 5 more authors.
Veterinary Microbiology | Year: 2012

Despite the long-term vaccination programs implemented in China, H9N2 avian influenza viruses (AIVs) continue to persist in chicken populations, even in vaccinated flocks. We previously demonstrated that H9N2 AIV isolated from chickens in China also underwent antigenic drift and evolved into distinct antigenic groups (C, D and E). To understand whether antigenic drift of viruses away from the vaccine strain partially contributed to the circulation of H9N2 AIV in China, we evaluated the protective efficacy of a commercial vaccine against different antigenic groups of H9N2 AIV. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group C viruses, but not those of the more recent groups D and E. Vaccinated chickens, even those with vaccine-induced HI titers of 1:1024, shed virus after being infected with A/chicken/Shandong/ZB/2007, a representative virus of antigenic group D. Genetic analysis showed that the representative viruses of antigenic groups D and E possessed greater numbers of amino acid substitutions in the hemagglutinin protein compared to the vaccine strain and the antigenic group C virus, and many of which were located in antigenic sites. Our results indicated that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection, and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection. Furthermore, the avian influenza vaccination policy also needs to be re-assessed, and increased veterinary biosecurity on farms, rather than vaccine application alone, should be implemented to prevent and control avian influenza. © 2011 Elsevier B.V.


Sun Y.,China Agricultural University | Pu J.,China Agricultural University | Jiang Z.,China Agricultural University | Guan T.,China Agricultural University | And 8 more authors.
Veterinary Microbiology | Year: 2010

H9N2 influenza viruses have been circulating in China since 1994, but a systematic investigation of H9N2 in northern China has not been undertaken since 2004. Here, using the sequences of 22 viruses we isolated from poultry and pigs in northern China during 2003-2008, in combination with sequences available in a public database, we analyzed the evolution of H9N2 influenza viruses in China from 1994 to 2008. Our findings demonstrated that the H9N2 viruses in China underwent extensive reassortment, and novel genotypes continued to emerge. Among 330 viruses, 54 genotypes were observed including 19 novel genotypes that have not been recognized before, and major genotypes were further divided into five series (BJ/94-, G1-, BG-, F/98- and Aq-series). Different epidemiological and biological features among these series were recognized. The BJ/94- and F/98-series viruses were circulating in both southern and northern China, while the other three series viruses were mainly detected in southern China. BJ/94-series influenza viruses predominated in China before 2000 and were gradually replaced by F/98-series viruses that became the predominant viruses since 2004. At least five antigenic groups could be identified over the study period, during which a significant antigenic drift likely occurred between 2002 and 2003. Animal experiments demonstrated that F/98-series viruses were able to replicate and transmit more effectively in chickens than BJ/94-series viruses. The continuing evolution of H9N2 influenza viruses in China emphasizes the importance of H9N2 influenza virus surveillance throughout this region to aid pandemic prediction and prevention. © 2010 Elsevier B.V.


Pu J.,China Agricultural University | Wang J.,China Agricultural University | Zhang Y.,China Agricultural University | Fu G.,China Agricultural University | And 4 more authors.
Virus Research | Year: 2010

The NS1 influenza virus gene is thought to play an important role in replication and pathogenicity during infection. Previous studies have shown that mutations in the highly pathogenic avian NS1 influenza virus gene can influence virulence. However, little is known regarding the pathogenic mechanism of the NS1 gene in low pathogenic avian influenza virus. We found that NS1 genes originating from two H3 avian influenza viruses, A/duck/Beijing/40/04 (Dk/BJ/40/04) and A/duck/Beijing/61/05 (Dk/BJ/61/05), possessing three amino acid residue differences at positions 127, 205 and 209 contributed to an altered virulence in rescued NS1 recombinant viruses on a A/WSN/33 (WSN) virus background (WSN:40NS1 and WSN:61NS1) in mice. To further determine the effect on pathogenicity, we generated a series of recombinant viruses with mutations at positions 127, 205 and 209 in the NS1 gene of WSN:61NS1. Experiments in mice indicated that when compared with WSN:61NS1, viruses with only single mutations enhanced incidence of infection in mice but were not lethal. Viruses bearing substitution of two amino acid residues in the NS1 protein replicated well in lung tissue and caused 20-100% mortality in mice. Our findings demonstrate that co-mutation of amino acid residues at multiple positions in the NS1 protein can increase the pathogenicity of influenza virus in mice. © 2010 Elsevier B.V.


Zhao X.,China Agricultural University | Sun Y.,China Agricultural University | Pu J.,China Agricultural University | Fan L.,China Agricultural University | And 9 more authors.
PLoS ONE | Year: 2011

Pandemic H1N1/2009 influenza virus, derived from a reassortment of avian, human, and swine influenza viruses, possesses a unique gene segment combination that had not been detected previously in animal and human populations. Whether such a gene combination could result in the pathogenicity and transmission as H1N1/2009 virus remains unclear. In the present study, we used reverse genetics to construct a reassortant virus (rH1N1) with the same gene combination as H1N1/2009 virus (NA and M genes from a Eurasian avian-like H1N1 swine virus and another six genes from a North American triple-reassortant H1N2 swine virus). Characterization of rH1N1 in mice showed that this virus had higher replicability and pathogenicity than those of the seasonal human H1N1 and Eurasian avian-like swine H1N1 viruses, but was similar to the H1N1/2009 and triple-reassortant H1N2 viruses. Experiments performed on guinea pigs showed that rH1N1 was not transmissible, whereas pandemic H1N1/2009 displayed efficient transmissibility. To further determine which gene segment played a key role in transmissibility, we constructed a series of reassortants derived from rH1N1 and H1N1/2009 viruses. Direct contact transmission studies demonstrated that the HA and NS genes contributed to the transmission of H1N1/2009 virus. Second, the HA gene of H1N1/2009 virus, when combined with the H1N1/2009 NA gene, conferred efficient contact transmission among guinea pigs. The present results reveal that not only gene segment reassortment but also amino acid mutation were needed for the generation of the pandemic influenza virus. © 2011 Zhao et al.


Sun Y.,China Agricultural University | Bi Y.,China Agricultural University | Bi Y.,CAS Institute of Microbiology | Pu J.,China Agricultural University | And 11 more authors.
PLoS ONE | Year: 2010

Background: The influenza viruses circulating in animals sporadically transmit to humans and pose pandemic threats. Animal models to evaluate the potential public health risk potential of these viruses are needed. Methodology/Principal Findings: We investigated the guinea pig as a mammalian model for the study of the replication and transmission characteristics of selected swine H1N1, H1N2, H3N2 and avian H9N2 influenza viruses, compared to those of pandemic (H1N1) 2009 and seasonal human H1N1, H3N2 influenza viruses. The swine and avian influenza viruses investigated were restricted to the respiratory system of guinea pigs and shed at high titers in nasal tracts without prior adaptation, similar to human strains. None of the swine and avian influenza viruses showed transmissibility among guinea pigs; in contrast, pandemic (H1N1) 2009 virus transmitted from infected guinea pigs to all animals and seasonal human influenza viruses could also horizontally transmit in guinea pigs. The analysis of the receptor distribution in the guinea pig respiratory tissues by lectin histochemistry indicated that both SAα2,3-Gal and SAα2,6-Gal receptors widely presented in the nasal tract and the trachea, while SAαa2,3-Gal receptor was the main receptor in the lung. Conclusions/Significance: We propose that the guinea pig could serve as a useful mammalian model to evaluate the potential public health threat of swine and avian influenza viruses. © 2010 Sun et al.


Wang J.,China Agricultural University | Sun Y.,China Agricultural University | Xu Q.,China Agricultural University | Tan Y.,China Agricultural University | And 5 more authors.
PLoS ONE | Year: 2012

H9N2 influenza viruses have been circulating worldwide in multiple avian species and have repeatedly infected humans to cause typical disease. The continued avian-to-human interspecies transmission of H9N2 viruses raises concerns about the possibility of viral adaption with increased virulence for humans. To investigate the genetic basis of H9N2 influenza virus host range and pathogenicity in mammals, we generated a mouse-adapted H9N2 virus (SD16-MA) that possessed significantly higher virulence than wide-type virus (SD16). Increased virulence was detectable after 8 sequential lung passages in mice. Five amino acid substitutions were found in the genome of SD16-MA compared with SD16 virus: PB2 (M147L, V250G and E627K), HA (L226Q) and M1 (R210K). Assessments of replication in mice showed that all of the SD16-MA PB2, HA and M1 genome segments increased virus replication; however, only the mouse-adapted PB2 significantly increased virulence. Although the PB2 E627K amino acid substitution enhanced viral polymerase activity and replication, none of the single mutations of mouse adapted PB2 could confer increased virulence on the SD16 backbone. The combination of M147L and E627K significantly enhanced viral replication ability and virulence in mice. Thus, our results show that the combination of PB2 amino acids at position 147 and 627 is critical for the increased pathogenicity of H9N2 influenza virus in mammalian host. © 2012 Wang et al.

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