Genetic Characterization of Porcine Parainfluenza Virus 1 (PPIV-1) in pig farms: First report of PPIV-1 in Thailand and Myanmar

Hnin Wai Phyu ^1,2 Kamonpan Charoenkul ^1,2 Chanakarn Nasamran ^1,2 Kitikhun Udom ^1,2 Eaint Min Phyu ² Yu Nandi Thaw ² Han Win Soe ² Supassama Chaiyawong ^1,2 Thant Nyi Lin ³ Min Thein Maw ⁴ Alongkorn Amonsin ^1,2*

• ¹ Center for Emerging and Re-emerging Diseases in Animals, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
• ² Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
• ³ Department of Veterinary Public Health, University of Veterinary Science, Yezin, Nay Pyi Taw, Myanmar, Nay Pyi Taw, Myanmar
• ⁴ Livestock Breeding and Veterinary Department, Ministry of Agriculture, Livestock and Irrigation,, Nay Pyi Taw, Myanmar

Porcine parainfluenza virus 1 (PPIV-1) is a paramyxovirus causing respiratory infections in pigs and has been reported worldwide. In this study, we conducted a crosssectional survey of PPIV-1 in pig farms in Thailand and Myanmar from January 2022 to December 2023. Nasal swab samples from pigs in Thailand (n=1042) and Myanmar (n=449) were collected from clinically healthy pigs and pigs with respiratory signs. PPIV-1 detection was carried out using the L gene-specific RT-PCR assay. Our results showed that 3.65% (38/1042) and 7.57% (34/449) were positive for PPIV-1 in Thailand and Myanmar, respectively. The viruses (n=15) were subjected to whole genome sequencing (n=4) and F and HN gene sequencing (n=11). Genetic and phylogenetic analyses showed that Thai PPIV-1 (n=7) was grouped into PPIV-1 lineage II (American lineage) and closely related to American and Chinese strains. On the other hand, one Thai PPIV-1 strain (n=1) and Myanmar PPIV-1 (n=7) belonged to lineage I (European lineage) and was closely related to European, Hong Kong (China), and South Korean strains. Our findings suggest that PPIV-1s from both lineages (I and II) are circulating in pigs in Thailand, and PPIV-1 of lineage I is circulating in pigs in Myanmar, suggesting high genetic diversity of PPIV-1 in the Southeast Asia region. This study is the first to report whole-genome sequences of PPIV-1 from pigs in Thailand and Myanmar.Our result provided insights and information about the current disease status and genetic diversity of PPIV-1 in pig farms, which will benefit further animal disease surveillance, prevention, and control.