New variants of porcine epidemic diarrhea virus, China, 2011

Abstract

In 2011, porcine epidemic diarrhea virus (PEDV) infection rates rose substantially in vaccinated swine herds. To determine the distribution profile of PEDV outbreak strains, we sequenced the full-length spike gene from samples from 9 farms where animals exhibited severe diarrhea and mortality rates were high. Three new PEDV variants were identified.

Figure 1

Clinical features of pigs infected with porcine epidemic diarrhea virus from pig farms in the People’s Republic of China, 2011. A) Litter of pigs infected with this virus, showing watery diarrhea and emaciated bodies. B) A representative emaciated piglet with yellow, water-like feces. C) Yellow and white vomitus from a representative sucking piglet. D) Thin-walled intestinal structure with light yellow water-like content. E) Congestion in the small intestinal wall and intestinal villi; desquamated epithelial cells from the intestinal villus (original magnification ×100). F) Congestion in the lamina propria of intestinal mucosa, and degeneration, necrosis, and desquamation of epithelial cells of the intestinal villi (original magnification ×400).

Figure 2

Phylogenetic trees of porcine epidemic diarrhea virus (PEDV) strains generated by the neighbor-joining method with nucleotide sequences of the full-length spike genes. Bootstrapping with 1,000 replicates was performed to determine the percentage reliability for each internal node. Horizontal branch lengths are proportional to genetic distances between PEDV strains. Black circles indicate PEDV field isolates from the 2011 outbreak in China. Scale bar indicates nucleotide substitutions per site.