Résumé
Since late 2010, porcine epidemic diarrhea virus (PEDV) has been re-emerging in central China. To explore the possible reason of the PEDV outbreaks, twelve PEDV field strains were isolated from different swine breeding farms in central China during 2010-2012, and molecular diversity, phylogenetic relationships of these strains with other PEDV reference strains were investigated. Sequence analysis of S, M and ORE3 genes revealed that the central China PEDV isolates had several specific nucleotides and amino acids which were different from PEDV reference strains. In addition, the entire S genes of eleven central China PEDV isolates were found to be nine nucleotides longer in length than CV777 and large number of amino acid variations was accumulated in the N-terminal region of S gene. Phylogenetic analysis showed that the central China PEDV isolates had close relationship with Korea strains (2007-2009), Thailand strains (2007-2008), Vietnam strains (2009-2010), Japan strains (2010), and other prevailing strains from other parts of China (2010-2012). However, they differed genetically from European strains (CV777, Brl/87), China strains (2003-2007) and the vaccine strains (CV777) used in China. These results imply that a rapid variation and evolution of central China PEDV strains has occurred in recent years, and a more efficient vaccine strain should be selected to prevent and control outbreaks of PEDV in China.