Molecular detection and genetic characterization of parrot bornavirus in captive psittacine birds in Thailand

Parrot bornavirus (PaBV), the etiological agent of proventricular dilatation disease (PDD), poses a significant threat to captive psittacine birds worldwide. This study investigated the prevalence, genotype distribution, and phylogenetic characteristics of PaBV in captive psittacine birds in Thailand. A total of 231 birds from three families (Psittaculidae, Psittacidae, and Cacatuidae) were sampled across five regions in Thailand. Nested PCR targeting the nucleoprotein gene detected PaBV in 13.85% (n=38) of samples, with 81.58% of positive cases being asymptomatic, suggesting a potential carrier state. Choanal swabs were the most effective for detecting PaBV, although some positive cases were identified exclusively in other specimen types, indicating the importance of using multiple sample types for accurate diagnosis. Genotyping revealed the presence of two viral variants: PaBV-2 and the more prevalent PaBV-4, with the latter being predominant and further classified into two distinct groups. The continued presence of PaBV in captive birds raises concern over possible spillover into native wild psittacine populations, several of which are classified as "Near Threatened" by the IUCN. These findings underscore the importance of regular monitoring and molecular surveillance in both captive and wild bird populations to inform effective disease management and conservation strategies.