Isolation and Characterization of Porcine Deltacoronavirus from Pigs with Diarrhea in the United States

Abstract

Porcine deltacoronavirus (PDCoV) is a novel coronavirus that causes diarrhea in nursing piglets. Following its first detection in the United States in February 2014, additional PDCoV strains have been identified in the United States and Canada. Currently, no treatments or vaccines for PDCoV are available. In this study, U.S. PDCoV strain OH-FD22 from intestinal contents of a diarrheic pig from Ohio was isolated in swine testicular (ST) and LLC porcine kidney (LLC-PK) cell cultures by using various medium additives. We also isolated PDCoV [OH-FD22(DC44) strain] in LLC-PK cells from intestinal contents of PDCoV OH-FD22 strain-inoculated gnotobiotic (Gn) pigs. Cell culture isolation and propagation were optimized, and the isolates were serially propagated in cell culture for >20 passages. The full-length S and N genes were sequenced to study PDCoV genetic changes after passage in Gn pigs and cell culture (passage 11 [P11] and P20). Genetically, the S and N genes of the PDCoV isolates were relatively stable during the first 20 passages in cell culture, with only 5 nucleotide changes, each corresponding to an amino acid change. The S and N genes of our sequenced strains were genetically closely related to each other and to other U.S. PDCoV strains, with the highest sequence similarity to South Korean strain KNU14-04. This is the first report describing cell culture isolation, serial propagation, and biological and genetic characterization of cell-adapted PDCoV strains. The information presented in this study is important for the development of diagnostic reagents, assays, and potential vaccines against emergent PDCoV strains.

Prevalence, complete genome sequencing and phylogenetic analysis of porcine deltacoronavirus in South Korea, 2014-2016

“…PDCoV infection is characterized by marked villous atrophy in the small intestine, which results in watery diarrhoea and vomiting, leading to dehydration and death in newborn piglets (Jung et al., ; Ma et al., ). This disease is symptomatically comparable to, but reportedly milder than, other porcine enteric coronavirus diseases caused by transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhoea virus (PEDV), with lower mortality rates in affected neonatal piglets (Hu et al., ). PDCoV belongs to the genus Deltacoronavirus within the family Coronaviridae of the order Nidovirales .…”

Point‐of‐care diagnostic assay for rapid detection of porcine deltacoronavirus using the recombinase polymerase amplification method

“…Since the first case of PDCoV isolation in Hong Kong in 2012, PDCoV infection has become prevalent in the pig herds across the world and caused huge economic losses to swine industry (Hu et al., ; Jung et al., ; Song et al., ; Wang et al., ; Xu et al., ; Zhang, ). Notably, the clinical sighs caused by PDCoV are very similar to that associated with other viral diarrhoea pathogens such as PEDV and TGEV, which makes it difficult to differential diagnosis.…”

“…At present, several diagnostic methods for rapid detection of PDCoV have been developed. Serological assays such as virus neutralization test, indirect fluorescent antibody assay and enzyme linked immunosorbent assay were reported to detect PDCoV‐specific antibodies (Hu et al., ; Luo et al., ; Zhang, ). However, the serological methods were not suitable for the detection of antibodies during the early stage of virus infection as antibody generation required a few days.…”

Cryo-Electron Microscopy Structure of Porcine Deltacoronavirus Spike Protein in the Prefusion State

“…PdCoV from the ␦ genus is a highly lethal viral pathogen in piglets (39)(40)(41). Compared to the extensive studies on ␣and ␤-coronavirus spikes, much less is known about the structure and function of ␦-coronavirus spikes.…”