Genetic variation analysis of reemerging porcine epidemic diarrhea virus prevailing in central China from 2010 to 2011

Abstract

Porcine epidemic diarrhea has re-emerged with devastating impact in central China since October 2010. To investigate and analyze the reason of this outbreak, the M and ORF3 genes of 15 porcine epidemic diarrhea viruses (PEDV), which were collected from different areas of central China during October 2010 and December 2011, were amplified by reverse transcriptase polymerase chain reaction, cloned, sequenced, and analyzed. Sequence analyses showed that the nucleotides and amino acids were changed at some sites in the M and ORF3 genes of the 15 PEDV strains compared with those genes of CV777 reference strain. Based on the phylogenetic analyses, PEDVs in central China and reference strains could be separated into three groups: G1, G2, and G3. The 15 PEDV strains belonged to G3 group and showed a close relationship with Korean strains (2007), Thai strains (2007-2008), and partial other Chinese strains (2010-2011), but differed genetically from European strains (Br1/87) and the vaccine strain (CV777 vs) being used in China. Furthermore, all 15 PEDV strains from central China and some other isolates in China from 2003 to 2007 (LJB-03, QH, and LZC) belonged to different group. Therefore, PEDV exhibits rapid variation and genetic evolution, and the currently prevailing PEDV strains in central China are a new genotype.

Fig. 1

Phylogenetic analysis based on amino acid sequences of M protein of 15 PEDV strains from central China and reference strains. The 15 strains sequenced in this study are marked initially by closed circle symbols

Fig. 2

Phylogenetic analysis based on amino acid sequences of ORF3 protein of 15 PEDV strains in central China and reference strains. The 15 strains sequenced in this study are marked initially by closed circle symbols