Thesis (M.Sc)--Chulalongkorn University, 2010

Porcine epidemic diarrhea virus (PEDV) spike (S) protein and membrane (M) protein 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 watery diarrhea piglets of various farms of the recent emerging outbreaks (2009-2010) were sequenced and analyzed. The results revealed high homology of the partial S gene of the current isolates at 98.9-100% and 99.7-100% identity of full M gene among these isolates despite dividing into two clades of different provincial origins. It should be note that the Vietnamese PEDVs contained high differences on nucleotide sequence of partial S gene with other reference isolates in Europe (Br1/87, CV777) and 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 recent isolates from China (JS-2004-2 and DX), Thailand (07NP01, 08NP02 and 08CB01) and Korea (KNU-0802 and CPF299). The results suggested that these Vietnamese PEDV isolates might have originated from the same Chinese ancestor and they have been undergoing genetic variation and forming a new PEDV genotype in Vietnam.