Isolation and genetic analysis of a variant porcine epidemic diarrhea virus in China

Epidemiological and genetic characterization of porcine epidemic diarrhea virus in the Mekong Delta, Vietnam, from 2015 to 2017

Porcine epidemic diarrhea (PED) virus (PEDV) is a highly contagious virus. PED was first identified in 2008 and has greatly affected the Vietnamese pig production economy. The aim of this study was to investigate the epidemiological and genetic characteristics of PEDV in piglet herds in the Mekong Delta, Vietnam. Diarrheal stool and intestinal samples from 2262 piglets from 191 herds in five provinces were collected to test for the presence of PEDV. Ten PEDV strains were randomly selected for sequencing, and four genes encoding PEDV structural proteins were analyzed. The rates of herds and samples positive for PEDV were 27.23% and 27.72%, respectively. In positive herds, the morbidity and mortality of PEDV-positive piglets were 97.97% and 79.06%, respectively, with most of the infected piglets under 7 days of age. Phylogenetic analysis showed that the 10 PEDV strains from this study clustered with genotype G2 strains from Vietnam and neighboring countries. Many amino acid substitutions were identified in important antigenic regions in the spike protein of the 10 strains when compared to four PEDV vaccine strains. This study provides novel insights into the epidemiology and genetic diversity of circulating PEDV strains, which could facilitate the development of an appropriate and proactive strategy for controlling PED.

Complete Genome Sequence of Variant Porcine Epidemic Diarrhea Virus Strain ZJ/ZX2018-C10, Isolated in Zhejiang, China, in 2018

We report here the complete genome sequence of porcine epidemic diarrhea virus (PEDV) strain ZJ/ZX2018-C10, isolated from infected piglets in Zhejiang Province, China. The genome sequence was highly similar to AH2012, a highly virulent Chinese PEDV strain.

We report here the complete genome sequence of porcine epidemic diarrhea virus (PEDV) strain ZJ/ZX2018-C10, isolated from infected piglets in Zhejiang Province, China. The genome sequence was highly similar to AH2012, a highly virulent Chinese PEDV strain. It will help in understanding the molecular and evolutionary characteristics of PEDV in China.

Isolation and characterization of a new porcine epidemic diarrhea virus variant that occurred in Korea in 2014

Outbreaks of porcine epidemic diarrhea (PED) have resulted in significant economic losses in the swine industry, and another PED outbreak occurred in 2014 in Korea. Isolating and culturing PED virus (PEDV) allow investigations into its pathogenesis and the development of vaccines and diagnostic assays. In this study, we successfully isolated two PEDV isolates (QIAP1401 and QIAP1402) from naturally infected piglets at Jeju-do, Korea. Viral propagation was confirmed in Vero cells based on cytopathic effect, immunofluorescence assay, reverse transcription-polymerase chain reaction, and electron microscopic analyses. The QIAP401 isolate propagated well in Vero cells for 70 passages, with titers of 10^6.5 to 10^7.0 50% tissue culture infectious dose/mL, which increased gradually with passaging. The nucleotide and amino acid sequences of the QIAP1401 isolate were determined and compared with those of other PEDV isolates. The QIAP1401 isolate was determined to be closely related to the USA/Minnesota271/2014 strain (> 99.9% nucleotide similarity) that was isolated in the USA in 2014. Phylogenetic analysis based on several PEDV genes suggested that a new PEDV variant is circulating in the Korean swine industry, with 93.08% similarity to the SM98 strain isolated in 1998. In addition, the QIAP1401 strain showed strong virulence in 3-day-old piglets and 11-week-old growing pigs.

Characterisation of porcine epidemic diarrhea virus isolates during the 2014-2015 outbreak in the Philippines

The viral agent of the porcine epidemic diarrhea (PED) was investigated during the reported 2014-2015 outbreaks in commercial farms in Central Luzon, Philippines. The study covered detection of PED virus (PEDV) in fecal and intestinal samples through reverse transcription PCR and sequence analysis of the nucleocapsid (N) gene. Results showed that 10 out of 34 fecal and intestinal samples examined were positive for PEDV. The partial nucleotide sequence of the N gene of the field samples showed 98-99% homologous to PEDV sequences registered in the GenBank. It was also noted that N gene sequences between field samples were 98% homologous. Interestingly, the partial sequences of the N genes of the field samples were genetically similar to the PEDV isolates from USA, China, Mexico, Canada and Japan. The phylogenetic tree analysis revealed that the Philippine samples clustered in group 2-1 of the PEDV, wherein the isolates of this group were responsible for the outbreaks in Asia and the USA. Analysis of the partial nucleotide and amino acid sequences revealed polymorphisms, deletions and insertions in the N-gene of the PEDV. Amino acid sequence alignment also showed deletions and insertion in the PEDV detected in the Philippines.

Coexistence of multiple genotypes of porcine epidemic diarrhea virus with novel mutant S genes in the Hubei Province of China in 2016

The emergence of highly virulent porcine epidemic diarrhea virus (PEDV) variants in China caused huge economic losses in 2010. Since then, large-scale sporadic outbreaks of PED caused by PEDV variants have occasionally occurred in China. However, the molecular diversity and epidemiology of PEDV in different provinces has not been completely understood. To determine the molecular diversity of PEDV in the Hubei Province of China, we collected 172 PED samples from 34 farms across the province in 2016 and performed reverse transcription polymerase chain reaction (RT-PCR) by targeting the nucleocapsid (N) gene. Seventy-four samples were found to be PEDV-positive. We further characterized the complete spike (S) glycoprotein genes from the positive samples and found 21 different S genes with amino acid mutations. The PEDV isolates here presented most of the genotypes which were found previously in field isolates in East and South-East Asia, North America, and Europe. Besides the typical Genotypes I and II, the INDEX groups were also found. Importantly, 58 new amino acids mutant sites in the S genes, including 44 sites in S1 and 14 sites in S2, were first described. Our results revealed that the S genes of PEDV showed variation and that diverse genotypes of PEDV coexisted and were responsible for the PED outbreaks in Hubei in 2016. This work highlighted the complexity of the epidemiology of PEDV and emphasized the need for reassessing the efficacy of classic PEDV vaccines against emerging variant strains and developing new vaccines to facilitate the prevention and control of PEDV in fields.