Molecular detection and genetic analysis of porcine bocavirus in Korean domestic swine herd

Abstract

Several porcine bocaviruses have been detected worldwide, and this report is the first to detect this virus from Korean domestic swine herd. Until now, three major genetic groups of porcine bocavirus (PBoV) were identified, named PBoV1, PBoV2 and PBoV3. This virus is known to show worldwide distribution including Europe, Africa, North America and Asia. However, there was no report yet about the presence of PBoV in Korean swine farms. The prevalence of porcine bocavirus was identified with various samples, including serum, tissue, feces and saliva from healthy or diseased pigs. In case of saliva, this is the first finding to prove the presence of PBoV in saliva of swine. Through PCR assay for each three groups of PBoV, I revealed the fact that all of PBoV showed higher infection rates in clinically diseased animals, especially for PBoV 1 (16.8%) and PBoV 3 (10.9%). This study also suggested that all porcine bocavirus groups primarily infected weaned piglets through the survey of positive rates using sera from different age group pigs. The genetic analysis was performed with the ORF3 gene, which is a unique gene to bocavirus to analyze the genetic relationship between the Korean strains and reference strains from other countries. The primer sets were designed for this study, and we got 14 different genomic sequences of Korean PBoV NP1 protein coding gene. As comparing these unique sequences of Korean strains with other dated sequences in GenBank that originated from other countries, we found that most Korean PBoV sequences showed high similarity with other typical strains with the one exception of 6133 (PBoV2) strain. The strain did not have high similarities (85.1%~87.7%) to any other sequences of PBoV, and it seemed a variant belonged to PBoV 2. This study characterized the current status of PBoV infection and the molecular epidemiologic information in Korean swine farms. In addition, several interesting facts of this new emerging virus were revealed including viral shedding through saliva.