Tissue localization, shedding, virus carriage, antibody response, and aerosol transmission of Porcine epidemic diarrhea virus following inoculation of 4-week-old feeder pigs

Abstract

We determined tissue localization, shedding patterns, virus carriage, antibody response, and aerosol transmission of Porcine epidemic diarrhea virus (PEDV) following inoculation of 4-week-old feeder pigs. Thirty-three pigs were randomly assigned to 1 of 3 groups for the 42-day study: inoculated (group A; n = 23), contact transmission (group B; n = 5), and aerosol transmission (group C; n = 5). Contact transmission occurred rapidly to group B pigs whereas productive aerosol transmission failed to occur to group C pigs. Emesis was the first clinical sign noted at 3 days postinoculation (dpi) followed by mild to moderate diarrhea lasting 5 more days. Real-time PCR detected PEDV in fecal and nasal swabs, oral fluids, serum, and gastrointestinal and lymphoid tissues. Shedding occurred primarily during the first 2 weeks postinoculation, peaking at 5-6 dpi; however, some pigs had PEDV nucleic acid detected in swabs collected at 21 and 28 dpi. Antibody titers were measurable between 14 and 42 dpi. Although feces and intestines collected at 42 dpi were PEDV negative by PCR and immunohistochemistry, respectively, small intestines from 70% of group A pigs were PCR positive. Although disease was relatively mild and transient in this age group, the results demonstrate that 4-week-old pigs are productively infected and can sustain virus replication for several weeks. Long-term shedding of PEDV in subclinically affected pigs should be considered an important source for PEDV transmission.

Evaluation and Comparison of the Pathogenicity and Host Immune Responses Induced by a G2b Taiwan Porcine Epidemic Diarrhea Virus (Strain Pintung 52) and Its Highly Cell-Culture Passaged Strain in Conventional 5-Week-Old Pigs

“…In this study, USA/KS/2013 isolate-inoculated pigs displayed fecal viral shedding primarily during the first two weeks with a peak at 5–6 DPI and fecal swabs that were positive for PEDV nucleic acid at 21 and 28 DPI in some pigs. Seroconversion was also noted at 14 DPI and reached a peak level at 21 DPI [22]. When the spike sequence of the USA/KS/2013 isolate was compared to the Taiwan PEDVPT isolate, we found that these two viruses share high sequence identity (99%).…”

Host Factors Affecting Generation of Immunity Against Porcine Epidemic Diarrhea Virus in Pregnant and Lactating Swine and Passive Protection of Neonates

“…Therefore, an experimental design that mimics natural airborne transmission with a very low amount of virus inocula in a very low volume or by blocking the inocula entering the esophagus after IN spray, is needed. Lastly, relatively low levels of PEDV replication can be detected in tissue-resident porcine macrophages in vivo [74][75][76] and in porcine alveolar macrophages in vitro [55]. Macrophages likely play a protective role against infection while serving as a reservoir for replicating virus.…”

Trypsin-independent porcine epidemic diarrhea virus US strain with altered virus entry mechanism

“…L-1-tosylamide-2-phenylethyl chloromethyl ketone (TPCK)-treated trypsin and GCDCA were purchased from Sigma-Aldrich (St Louis, MO) and elastase from porcine pancreas was obtained from Promega (Madison, WI). For the isolation of an US PEDV strain, the day 4 intestinal contents from a pig inoculated with a stool sample from an Indiana farm with a PEDV outbreak in 2013 [33] were diluted in minimum essential medium (MEM) for 1:10 and filtrated using a 0.2 μm membrane filter. The prepared sample was inoculated to confluent Vero cells grown in the 6-well plates.…”