Abstract
BACKGROUND AND AIM: Porcine bufavirus (PBuV) is an emerging enteric parvovirus increasingly reported in swine populations worldwide, but its epidemiological and genomic characteristics remain poorly understood in Southeast Asia. This study aimed to conduct a cross-sectional survey to determine the occurrence of PBuV in pig farms in Myanmar and to genetically characterize circulating Myanmar-PBuVs using whole-genome sequencing (WGS). MATERIALS AND METHODS: Between January and September 2023, 445 rectal swab samples were collected from pigs of various age groups and clinical statuses across 19 pig farms in the Yangon and Nay Pyi Taw Regions. Samples were screened using nested polymerase chain reaction (PCR) targeting the nonstructural protein 1 (NS1) gene. Seven PCR-positive samples were selected for WGS based on farm location, animal age, collection time, and amplicon quality. Phylogenetic analyses of whole genomes and NS1, viral protein 1 (VP1), and viral protein 2 (VP2) genes were performed using maximum-likelihood methods. Nucleotide and amino acid identities, conserved motifs, and unique mutations were assessed to determine genetic relationships with global PBuV and bufavirus (BuV) lineages. RESULTS: PBuV positivity was 15.06% (67/445; 95% confidence interval: 11.9-18.7), with detection in both diarrheic and healthy pigs. Fattening pigs exhibited the highest positivity (36.55%), and PBuV occurrence was significantly associated with winter months (p < 0.05). Seven Myanmar-PBuVs were successfully sequenced and clustered within the PBuV clade, showing close genetic relatedness to Austrian and Chinese PBuVs. Myanmar-PBuVs shared 91.81%-100% whole-genome nucleotide identity, with substantially lower identity (48%-63%) to BuVs from humans, dogs (Canis lupus familiaris), bats (various species), and rats (Rattus spp.). Conserved NS1, VP1, and VP2 motifs were preserved; however, unique amino acid insertions in NS1 (notably in CU34347) and several VP2 substitutions suggested potential region-specific evolution. CONCLUSION: This study provides the first genomic evidence of PBuV circulation in Myanmar and expands the global PBuV sequence database. The high detection in fattening pigs, seasonal trends, and phylogenetic proximity to European and Chinese strains highlight possible transboundary introduction pathways. Genetic similarities between Myanmar-PBuVs and human BuV in VP1/VP2 underscore the importance of One Health surveillance. Broader-scale longitudinal studies are needed to clarify PBuV evolution, disease association, and zoonotic potential.