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Genetic characterization of Porcine reproductive and respiratory syndrome (PRRS) demonstrated that there are two genotypes, European (type I) and North American (type II), currently circulating in the world. PRRSV contains a 15kb-size genome encoding structural proteins in the 3’ end.
In 2013, six blood samples from pigs experiencing severe respiratory diseases in an Ohio pig farm were submitted to the Animal Disease Diagnostic Laboratory of Ohio Department of Agriculture. All samples were tested positive for PRRSV using a real-time RT-PCR assay. The CT values of these samples ranged from 15.85 to 28.38. Virus isolation was carried out using MARC-145 cell line. Cytopathic effect was observed after 4 days post inoculation. Whole genome sequencing was subsequently completed for the samples. The whole genome analysis showed that this PRRSV strain (OH28372) has 92% or even lower nucleotide similarity to the published sequences in GenBank including XW001 and NADC30. The ORF5 gene of OH28372 has 96% nucleotide similarity to the other sequences in GenBank. In addition, OH28372 has a deletion of 13 nucleotides in the 3’ untranslated region. In consistent with genomic analysis, phylogenetic study of the complete genome showed that OH28372 is more closely related to the two recent US strains (XW001 and NADC30) under the North American lineage.
This study highlights the importance of continued monitoring of PRRSV evolution using genomic sequencing.
L. Wang, Y. Zhang. Genomic sequencing and analysis of a new porcine reproductive and respiratory syndrome virus isolate from Ohio: virus continues change. 2014 North American PRRS Symposium.
