Genetic Characterization of Porcine Epidemic Diarrhea Virus (PEDV) Isolates from Southern Vietnam during 2009-2010 Outbreaks

Porcine epidemic diarrhea virus (PEDV) spike (S) glyprotein and membrane (M) glycoprotein genes are believed to have genetic variation. The heterogeneity in those genomic sequences has been reported and is known essentially for the diverse PEDV pathogenicity. Eight southern Vietnamese PEDVs collected from severe watery diarrhea piglets of the recent emerging outbreaks (2009-2010) were sequenced and analyzed. The results revealed high nucleotide homology of the partial S gene of the current isolates at 98.9-100% and 99.7-100% identity of the full M gene among these isolates despite dividing into two subclusters of different provincial origins. It should be noted that the Vietnamese PEDVs contained high differences on nucleotide sequence of partial S gene with other reference isolates in Europe (Br1/87, CV777) and in Korea (Spk1, Chinju99, DR13 and KNU-0801). The phylogenetic relationship of both partial S and M protein genes indicated that the current Vietnamese PEDVs were in the same cluster with the Chinese isolates (JS-2004-2 and DX), the Thai isolates (07NP01, 08NP02 and 08CB01) and the recent Korean isolates (KNU-0802 and CPF299). The results suggested that the current Vietnamese PEDV isolates might have originated from the same Chinese ancestor undergoing genetic variation and possibly forming a new PEDV genotype in Vietnam.