The Investigation Of Molecular Epidemiology Of Porcine Epidemic Diarrhea Virus In2011

Porcine epidemic diarrhea(PED), caused by Porcine epidemic diarrhea virus (PEDV), is a high degree of exposure to intestinal infectious diseases of swine, characterized by severe enteritis, vomiting, diarrhea and dehydration. The disease is widely distributed in the world, causing serious economic losses to the world’s pig industry.In December2010, severe diarrhea(suspected to be infected PEDV), a high incidence and mortality,were observed on most swine farms in most provinces of China. So, in2011, Porcine intestine and fecal samples were collected from219piglets with watery diarrhea and dehydration at55different farms in10provinces and two municipalities in China. All the samples were detected by colloidal gold and RT-PCR. The result is that there are9pig farms(16.36%) were infected with PEDV lonely,29pig farms(52.73%) were infected with mixed infection of TGEV and PoRV,73samples(33.33%) were infected with PEDV lonely,61samples (27.85%) were infected with mixed infection of TGEV and PoRV. The rest diarrhea pathogen is the other gastro-intestinal disease pathogen. The result showed that:PEDV is dominant in the diarrhea pathogen.In this study,27PEDV S genes,20PEDV N genes and25PEDV PRF3genes were cloned in the pGEM-T and pMD18-T vector, respectively,and then sequenced. Sequence analysis and phylogenetic tree showed phylogenetic relationships and genetic variation of PEDV.7of27PEDV S gene composed of4149nucleotides, one of4152nucleotides, two of4146nucleotides, one of4170nucleotides, one of4158nucleotides,15of4161nucleotides. PEDV S gene nucleotide sequences showed homologies of93.6%-99.9%. With PEDV reference strains, homology is92.8%-100%. The emergence of PEDV genetic variation is caused by the change of S protein amino acid. The reason is that S1gene diversity resulting from point mutations, insertion, deletion. Compared with the reference strains, there are point mutations, insertion, deletion. The nucleotides insertion and deletion in the17isolates are similar with KNU-0901, KNU-0903etc. Their glycosylation sites are similar with KNU-0901etc, too. Phylogenetic tree showed that PEDV S genes are divided into two groups. Group Ⅰ is including17isolates and South Korea strains KNU-0901, KNU-0903etc. Group Ⅱ including the other isolates, JS-2004-2and CV777etc. its biological function is not clear.20PEDV N genes are including1326nucleotides, with nucleotide sequence homologies of94.9%～100%. PEDV N genes is conservative.Phylogenetic tree showed that PEDV N genes are divided into three groups.23of25ORF3genes composed of675nucleotides, encoding224amino acids. The others, contain an open reading frame of276nucleotides, composed of627nucleotides, lack of49nucleotides between245～293nucleotides. Phylogenetic tree showed that PEDV ORF3genes are divided into three groups. The Chinese PEDV isolates (except CH/BJ/2011,CH/HLJHH-1/2011) and South Korea strains have a close genetic relationshop. CH/BJ/2011, CH/HLJHH-1/2011and vaccine strains have a close genetic relationshop.