PHYLOGENETIC RELATIONSHIP OF THE PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUSES (PRRSV) ISOLATED IN VIETNAM

Abstract

In this study, 24 porcine reproductive and respiratory syndrome virus (PRRSV) samples isolated from 16 provinces in Vietnam in 2013 were investigated, and the phylogenetic relationship of these viruses was constructed based on the amino acid sequences of ORF5 and Nsp2 genes. The sequencing results of these genes indicated the high variation compared to the sequence of 07/QN strain (Genbank code: FJ394029.1) isolated in Quang Nam province. The identity of amino acid sequences deducted from the nucleotide sequences between the 24 isolates and 07/ QN strain was also analysed; 19 variations in ORF5 gene and 66 variations in Nsp2 gene were found. Especially, three isolates VN/ QT-2013, VN/NA-2013, and VN/ND-2013 were found to possess three-continuous amino acid deletions (869-871) within Nsp2 gene. Phylogenetic analyses based on the ORF5 and Nsp2 amino acids indicated that all these isolates were grouped into PRRSV type II (North American genotype) and they were highly similar to PRRSV strains isolated in China.