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Introduction: The aim of this study was to identify the genetic characteristics and molecular genotyping of duck hepatitis A virus (DHAV) isolated in Vietnam during [2009][2010][2011][2012][2013]. Methodology: Thirty duckling livers from outbreaks between 2009 and 2013 in seven provinces were collected and identified by polymerase chain reaction (PCR). Then, VP1 genes of eleven positive samples and two attenuated vaccine strains were sequenced and analyzed. Results: Genotypic and phylogenetic analyses indicated that the 13 Vietnamese isolates were classified into two genotypes, DHAV-1 and DHAV-3. The rate of identity and homology was 91%-100% between the 10 Vietnamese and 26 global strains of DHAV-3, and 92%-100% between 3 Vietnamese and 16 strains of DHAV-1. Between the DHAV-3 and DHAV-1 strains, the divergence reached 30%. At the C-terminal of VP1 for the different strains, a hypervariable region was observed, and notably, six of the Vietnamese DHAV-3 strains in this study showed four consistent differences (at positions T184M, Q200H, K207N, and K214R) within this group that were distinct from all other DHAV-3 strains. Conclusions: This is the first report of molecular characterization of DHAVs in Vietnam. At least two genotypes were identified, DHAV-1 and DHAV-3, with diversified clades within and between genotypes. DHAV-3 seemed to be dominant in Vietnam.

The complete sequence for viral protein 2 (VP2) of canine parvovirus (CPV) was obtained from 33 isolates collected from dogs with clinical symptoms and a vaccine in Vietnam from Mar 2017-June 2019. Molecular analysis revealed the descent evolution in CPV-2c-"new", forming a "new var." sublineage of the substantial 5G, 447M mutations restricted to the Vietnamese isolates in the epitope stretches. These were found besides the common 80R,

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Citation of This ArticleDoan HT, Le XK, Do R, Nguyen K, Le TH: Sequencing and phylogenetic analysis reveal the prevalence of duck hepatitis A virus genotype 3 in Vietnam. Kafkas Univ Vet Fak Derg, 23 (3): 369-376, 2017. DOI: 10.9775/kvfd.2016 Abstract Duck hepatitis A virus (DHAV) causes an acute and highly contagious disease in young ducklings worldwide. Despite the widespread use of the DHAV vaccine, many outbreaks still occur in Vietnam. In this study, we determined the full-length genome sequence of two DHAV isolates (NC and NT) obtained from infected ducks in 2009 and 2013, and compared them with the attenuated DHAV-1 vaccine strain (namely, VXXT) currently used in Vietnam. The NC and NT strains belong to the virulent DHAV-3 genotype, and their genomes consist of 7791 and 7790 nucleotides (nt), respectively. Both genomes contain one large open reading frame (ORF) of 6756 nt, encoding a polyprotein of 2251 amino acids and possess a typical picornavirus genome organization. The majority of predicted C-terminal cleavage sites in the polyprotein were Q/S or Q/G. Phylogenetic analysis of the nucleotide sequence of the full ORF revealed that all virulent Vietnamese strains are closely related to Chinese DHAV-3 strains. Noticeably, the virulent Vietnamese DHAV-3 strains had relatively low nucleotide identity with the DHAV-1 vaccine strain (73.5%). The study showed that an antigenicity-matched DHAV-3 vaccine is urgently required for use in Vietnam. Keywords: Duck hepatitis A virus, Genotype, Genome, Phylogenetic Sekans ve Filogenetik Analiz Vietnamda Ördek Hepatitis A Virüs Genotip-3'ün Prevalansını Ortaya Koymaktadır Özet

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The unified genotypic classification scheme (genotypes A0, A1–A8, and B1–B5) was proposed and applied for the classification of the infectious bursal disease virus (IBDV). Since 1987, IBDVs have circulated and evolved in Vietnam, but little is known about the genotypes present. The IBDV samples were collected in 1987, 2001–2006, 2008, 2011, 2015–2019, and 2021 in 18 provinces. We conducted phylogenotyping analysis based on the alignment of 143 VP2-HVR (439 bp, nt 628–1066; aa 210–355 in VP2), including 64 Vietnamese isolates and two vaccines, and 82 VP1 B-marker (725 bp, nt 13–737; aa 4–245 in VP1) sequences, including four Vietnamese isolates and one vaccine. The analysis revealed three A-genotypes, A1, A3, and A7, and two B-genotypes, B1 and B3, among the Vietnamese IBDVs. The IBDV strains showed the lowest average evolutionary distance at 8.6% between A1 and A3 and the highest (21.7%) between A5 and A7, while 14% was between B1 and B3 and 17% between B3 and B2. The signature residues 222T - 253Q - 256V - 294L - 299(S/N) appeared to be unique for the genotype A2; the 222A - 253Q - 256I - 294I - 299S for the A3, the 222T - 253Q - 256V - 294L - 299N for the A5, the 222Q - 253E - 256K - 294L - 299S for the A6, and the 222A - 253Q - 256A - 294L - 299S for the A8, and each of these could be the genotypical motif for genotypic discrimination. The timeline statistical summary revealed that the A3-genotype predominated (79.8% presence) in Vietnam from 1987 to 2021 and that it has remained dominant in circulating IBDVs over the last five years (2016–2021).

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