Wanjun Zhu

Seroepidemiological Evidence of Avian Influenza A Virus Transmission to Pigs in Southern China

ABSTRACT Recently, three novel avian-origin swine influenza viruses (SIVs) were first isolated from pigs in Guangdong Province, southern China, yet little is known about the seroprevalence of avian influenza viruses among pigs in southern China. Here, we report for the first time the seroprevalence of avian H3, H4, and H6 influenza viruses in swine populations and the lack of seroepidemiological evidence of avian H5 influenza virus transmission to pigs in China.

Genetic evolution and phylogenetic analysis of porcine circovirus type 2 infections in southern China from 2011 to 2012

Porcine circovirus type 2 (PCV2), the primary causative agent of porcine circovirus-associated diseases (PCVADs), is a serious economic problem for the swine industry worldwide. Three major PCV2 genotypes (PCV2a, PCV2b, and PCV2c), have been identified. To explore the prevalence of different subgroups of PCV2 in southern China, 66 PCV2 isolates collected during 2011-2012 were analyzed. PCV2b was the predominant genotype circulating in southern China from 2011 to 2012. Moreover, subtype 1C was the predominant subtype. Comparisons of the complete ORF2 nucleotide sequence revealed 89.3-100% homology and 87.2-100% amino acid sequence identities. The deletion at position 1042 and two nucleotide substitutions at positions T1035A or T1033C were important for the PCV2 evolution. Base-by-base of ORF2 comparison showed that the PCV2 evolution trace was PCV2a to PCV2b-1A1B to PCV2b-1C. These results contribute to the understanding of PCV2 epidemiology in southern China.

Complete Genome Sequence of a Novel Avian-Like H3N2 Swine Influenza Virus Discovered in Southern China

ABSTRACT We report here the complete genomic sequence of a novel avian-like H3N2 swine influenza virus containing an H5N1 highly pathogenic avian influenza virus segment that was obtained from swine in southern China. Phylogenetic analysis indicated that this virus might originate from domestic aquatic birds. The sequence information provided herein suggests that continuing study is required to determine if this virus can be established in the swine population and pose potential threats to public health.

Avian influenza H9N2 seroprevalence among swine farm residents in China

In parts of southern China, some large‐scale swine farms are adjacent to lakes and ponds that are home to many types of birds. Some swine farms will also raise poultry for consumption and sale. Swine farms in rural China may be the source of the AIV outbreak. A seroepidemiological study was conducted among swine farm residents to understand the prevalence of antibodies against avian influenza virus (AIV) H9N2 in southern China. A total of 2,006 swine farm residents were sampled. Serum samples were tested for the presence of antibodies against H9N2 AIV by hemagglutination inhibition (HI) and microneutralization assays. A total of 37 serum samples from swine farm residents were HI positive for A/chicken/Guangdong/V/2008(H9N2), and 24 serum samples (all of which were also HI positive) were microneutralization assays positive for A/chicken/Guangdong/V/2008(H9N2). Due to the special pig farming model in southern China, the residents are in close contact with different kinds of birds. Thus, controlling bird‐to‐human transmission of AIV in swine farms with poultry may be an important means of preventing widespread AIV infection in humans. J. Med. Virol. 86:597–600, 2014.

Molecular epidemiology of PRRSV in South China from 2007 to 2011 based on the genetic analysis of ORF5

Porcine reproductive and respiratory syndrome virus (PRRSV) has proven to be highly genetically variable; however, comprehensive information regarding the viruss genetic diversity in South China is limited. In this study, a total of 3199 clinical samples were collected from 267 pig farms suspected of PRRSV infection between 2007 and 2011. The ORF5 genes of 51 PRRSV-positive samples were sequenced and analyzed. The 51 study strains were divided into three primary subgenotypes. Fourty-five of the strains belonged to subgenotype I and were closely related to the highly pathogenic PRRSV (HP-PRRSV) strains. The subgenotype I strains were generally clustered into genetically similar groups by year. Only one of the strains belonged to subgenotype II, clustering with the classical North American type, VR2332. Five of the strains were grouped into subgenotype III, which occupied a separate branch and was closely related to the recently isolated novel field strains, QYYZ and GM2. The 5 subgenotype III strains shared an amino acid identity with the remaining 46 study strains ranging from 79.6%-83.6%. Amino acid analysis showed extensive mutations in subgenotype III; the diverse genetic mutations of these novel strains are of great concern.

Complete Genome Sequence of Duck Tembusu Virus, Isolated from Muscovy Ducks in Southern China

ABSTRACT We report here the complete genomic sequence of the duck Tembusu virus (DTMUV) WJ-1 strain, isolated from Muscovy ducks. This is the first complete genome sequence of DTMUV reported in southern China. Compared with the other strains (TA, GH-2, YY5, and ZJ-407) that were previously found in eastern China, WJ-1 bears a few differences in the nucleotide and amino acid sequences. We found that there are 47 mutations of amino acids encoded by the whole open reading frame (ORF) among these five strains. The whole-genome sequence of DTMUV will help in understanding the epidemiology and molecular characteristics of duck Tembusu virus in southern China.

Live poultry market workers are susceptible to both avian and swine influenza viruses, Guangdong Province, China.

Abstract Guangdong Province is recognized for dense populations of humans, pigs, poultry and pets. In order to evaluate the threat of viral infection faced by those working with animals, a cross-sectional, sero-epidemiological study was conducted in Guangdong between December 2013 and January 2014. Individuals working with swine, at poultry farms, or live poultry markets (LPM), and veterinarians, and controls not exposed to animals were enrolled in this study and 11 (4 human, 3 swine, 3 avian, and 1 canine) influenza A viruses were used in hemagglutination inhibition (HI) assays (7 strains) and the cross-reactivity test (9 strains) in which 5 strains were used in both tests. Univariate analysis was performed to identify which variables were significantly associated with seropositivity. Odds ratios (OR) revealed that swine workers had a significantly higher risk of elevated antibodies against A/swine/Guangdong/L6/2009(H1N1), a classical swine virus, and A/swine/Guangdong/SS1/2012(H1N1), a Eurasian avian-like swine virus than non-exposed controls. Poultry farm workers were at a higher risk of infection with avian influenza H7N9 and H9N2. LPM workers were at a higher risk of infection with 3 subtypes of avian influenza, H5N1, H7N9, and H9N2. Interestingly, the OR also indicated that LPM workers were at risk of H1N1 swine influenza virus infection, perhaps due to the presence of pigs in the LPM. While partial confounding by cross-reactive antibodies against human viruses or vaccines cannot be ruled out, our data suggests that animal exposed people as are more likely to have antibodies against animal influenza viruses.

Mutagenesis analysis of porcine reproductive and respiratory syndrome virus nonstructural protein 7

Nonstructural protein 7 (nsp7), which is flanked by nsp6 and nsp8, is one of the most conserved nonstructural proteins of porcine reproductive and respiratory syndrome virus (PRRSV). Nonstructural protein (nsp)-specific antibodies are produced in high titers in response to virus replication, especially against nsp1a, nsp1b, nsp2, and nsp7. However, many regional aspects of nsp7 are still veiled, such as its impact on viral replication and virulence or the immunological mechanism between virus and host. Based on the structure of the predicted nsp7 domain, we have constructed a series of large mutations and deletions. We ultimately demonstrated all mutations (nsp7, nsp7α/nspβ) and the majority of substitutions of nsp7 affected the PRRSV replicative cycle in some ways and were fatal for viral recovery, which indicates that these are significant to structure or function of the nsp7. What’s more, the mutant vOKXH-nsp7 (F40A) indeed caused some of the variation compared with the parental virus vOKXH-GD, which shortens the amount of time needed to reach its highest viral titer, and decreases the concentration of the highest viral titer, obstructing viral mRNA and protein synthesis. Consequently, these valuable results possibly provide the first direct evidence that the nsp7 is really a critical protein domain for the RNA synthesis and the translation of viral protein of PRRSV.

Lack of evidence of avian-to-human transmission of avian influenza A (H5N1) virus among veterinarians, Guangdong, China, 2012.

BACKGROUND Cases of human infections with H5N1 avian influenza viruses have been reported all over the world with the reason of direct contact with sick or diseased poultry, which suggests the direct contact with poultry may be one of the major risk factors for human infection. OBJECTIVES In this study, we estimated the seroprevalence of antibodies against avian influenza A (H5N1) virus in veterinarians with exposure to avians. STUDY DESIGN From May 21, 2011 through April 22, 2012, 406 veterinarians exposure to poultry in Guangdong province were interviewed a questionnaire. A serum specimen was collected from participants to test for H5N1 antibodies by HI and NT assay. RESULTS None of the 406 sera from occupationally exposed veterinarians was positive according to the HI test and the NT test with the H5N1 AIV. CONCLUSION Our seroepidemiologic survey suggests that the risk of avian-to-human transmission of the H5N1 AIV is very low based on the samples that we tested. However, prevention regarding the risk of H5N1 AIV transmission is essential and should be recommended as public health measures.

Complete genome sequence of a novel duck hepatitis A virus discovered in southern China.

ABSTRACT We report here the complete genomic sequence of a novel duck hepatitis A virus (DHAV) isolated from mixed infections with DHAV type 1 (DHAV-1) and DHAV-3 in ducklings in Southern China. The whole nucleotide sequence had the highest homology with the sequence of DHAV-3 (GenBank accession number DQ812093) (96.2%). To our knowledge, this is the first report of gene rearrangement between DHAV-1 and DHAV-3, and it will help to understand the epidemiology and molecular characteristics of duck hepatitis A virus in Southern China.