Characterization of Porcine Epidemic Diarrhea Virus Isolate US/Iowa/18984/2013 Infection in 1-Day-Old Cesarean-Derived Colostrum-Deprived Piglets

Abstract

Porcine epidemic diarrhea virus (PEDV) was first recognized in North America in April 2013 and has since caused devastating disease. The objective of this study was to characterize disease and viral detection associated with an original North American PEDV isolate inoculated in neonatal piglets. Thirty-six 1-day-old cesarean-derived and colostrum-deprived piglets were randomly assigned to the control (n ¼ 16) or challenged group (n ¼ 20); the latter were orogastrically inoculated with 1 ml of US/Iowa/ 18984/2013 PEDV isolate titered at 1 Â 10 3 plaque-forming units per milliliter. Rectal swabs were collected from all piglets prior to inoculation and every 12 hours postinoculation (hpi) thereafter, with 4 control and 5 challenged piglets euthanized at 12, 24, 48, and 72 hpi. One piglet had a positive real-time quantitative polymerase chain reaction test on rectal swab at 12 hpi, and all remaining piglets were positive thereafter, with highest viral quantities detected at 24 and 36 hpi. Diarrhea was evident in 30% and 100% of challenged piglets at 18 and 24 hpi, respectively. Viral antigen was detected in enterocytes by immunohistochemistry in the duodenum and ileum of piglets euthanized at 12 hpi and was apparent throughout the small intestine of all piglets thereafter, with villus height:crypt depth ratios consistently below 4:1. Viremia was confirmed in 18 of 20 pigs at euthanasia. Clinical disease was severe and developed rapidly following infection with an original North American PEDV isolate, with lesions, viremia, and antigen detection possible by 12 hpi.

Pathogenesis comparison between the United States porcine epidemic diarrhoea virus prototype and S-INDEL-variant strains in conventional neonatal piglets

“…Previous studies showed that viraemia can occur in the acute stage of infection with US PEDV prototype isolates (Jung et al, 2014;Madson et al, 2016). In the present study, we also detected PEDV RNA in serum samples.…”

“…In the current study, high levels of PEDV RNA were detected in small intestine, caecum, colon and mesenteric lymph nodes, while low levels of PEDV RNA were detected in non-enteric tissues (tonsil, heart, lung, liver, spleen, kidney and muscle) from pigs inoculated with either prototype or S-INDEL-variant PEDV. Previous studies indicated that PEDV viral antigen (US prototype isolates) could be detected in small intestine, mesenteric lymph node, and some colon and spleen tissues (Jung et al, 2014(Jung et al, , 2015bMadson et al, 2016), but other non-enteric tissues such as lung, heart, kidney and liver were all negative for PEDV antigen (Madson et al, 2016). Therefore, detection of PEDV RNA does not necessarily mean that PEDV replicates in all of these non-enteric tissues.…”

“…The pathogenicity of the US PEDV prototype strain has been evaluated in gnotobiotic (Jung et al, 2014) Caesarean-derived colostrum-deprived (Liu et al, 2015;Madson et al, 2016) and conventional pigs (Jung et al, 2015a;Madson et al, 2014;Thomas et al, 2015); these studies experimentally confirmed that the US PEDV prototype isolates are highly virulent. Evaluation of the pathogenicity of the US S-INDEL-variant strain in experimentally infected pigs has not been reported until recently (Lin et al, 2015a), when we were in the process of revising this manuscript.…”

Porcine deltacoronavirus infection: Etiology, cell culture for virus isolation and propagation, molecular epidemiology and pathogenesis

“…In experimental PEDV infections in seronegative suckling pigs, during the incubation period, i.e. at approximately PIH 12-24, PEDV antigen-positive cells were seen throughout the small intestine and as many as 30-100% of the absorptive epithelial cells were positive (Debouck et al, 1981;Madson et al, 2015), consistent with fecal virus shedding in subclinical pigs. After that, during the clinical period, moderate to large numbers of PEDV antigen-positive cells were observed throughout the small intestine (Debouck et al, 1981;Jung et al, 2015a;Madson et al, 2015).…”

Characterization of Chinese Porcine Epidemic Diarrhea Virus with Novel Insertions and Deletions in Genome

“…Additionally, a portion of the jejunum and ileum were fixed in 10% neutral buffered formalin for histopathology. The villous atrophy is a typical histopathological change of the infection of a highly virulent PEDV44454647. And the villous height and crypt depth (VH:CD) ratios would be calculated using a computerized image system with as previous described44.…”