Detection and association of porcine bocaviruses 1 and 3 and porcine parvovirus 4 with postweaning multisystemic wasting syndrome (PMWS) in Brazil

The increasing identification of novel parvoviruses in swine has raised questions about their role in multifactorial syndromes like PMWS. This study used PCR to investigate the presence of porcine parvovirus 4 (PPV4), porcine bocavirus 1 (PBoV1), and porcine bocavirus 3 (PBoV3) in tissue and serum samples from pigs with or without PMWS in Brazil. PPV4 was significantly associated with PMWS, showing a six-fold higher frequency of DNAemia in affected animals (41.2%) than in controls (6.7%). In contrast, no association was found for PBoV1 or PBoV3, although both exhibited a clear tropism for lymphoid tissues. High detection rates of all three viruses in healthy adult pigs suggested possible viral persistence. As expected, PCV2 was detected in all tissues from every PMWS-affected pig. These findings delineate a hierarchy of involvement: PCV2 as the essential pathogen, PPV4 as a potential exacerbating co-factor linked to viremia, and bocaviruses as common bystanders. Further studies are needed to elucidate their pathogenic potential and interactions.