Experimental Infection of Young Pigs with an Early European Strain of Porcine Epidemic Diarrhoea Virus and a Recent US Strain

Abstract

Outbreaks of porcine epidemic diarrhoea (PED) were reported across Europe during the 1980s and 1990s, but only sporadic outbreaks occurred in recent years. PED virus (PEDV) spread for the first time into the USA in 2013 and has caused severe economic losses. Retrospectively, it was found that two different strains of PEDV have been introduced into the United States, both are closely related to strains circulating in China where a new wave of the disease occurred from 2010 onwards. Since autumn 2014, new outbreaks of PED have occurred in Europe. In this study, weaned piglets were inoculated with an early European isolate (Br1/87) or faecal/intestinal suspensions derived from pigs infected with a recent European strain of PEDV (from Germany) or a US strain of PEDV. No evidence for infection resulted from inoculation of pigs with the German sample that contained high levels of PEDV RNA; there were no clinical signs, excretion of viral RNA or anti-PEDV antibody production. In contrast, all the pigs in the other two groups showed evidence of infection. Mild clinical signs of disease, mainly diarrhoea, occurred in piglets inoculated with the Br1/87 and US PEDV strains. PEDV RNA was detected throughout the intestine in euthanized animals at 4 days post-inoculation. In addition, within these animals, low levels of viral RNA were detected in lungs and livers with higher levels in spleens. Seroconversion against PEDV occurred in all surviving infected animals within 10 days. PEDV RNA excretion occurred for at least 2 weeks. The US PEDV RNA was detected at low levels in serum samples on multiple days. It is apparent that current diagnostic systems can detect infection by the different virus strains.

A G3P[13] porcine group A rotavirus emerging in China is a reassortant and a natural recombinant in the VP4 gene

“…Many types of viruses cause diarrhoea in animals, including TGEV (Zhang, Zhu, Zhu, Chen et al., ), swine enteric coronaviruses (SeCoVs) (Belsham et al., ), PEDV (Lohse et al., ; Tian et al., ; Zhang, Tian et al., ), porcine deltacoronavirus (Lee et al., ; Mai et al., ; Saeng‐Chuto et al., ) and rotaviruses (Kim et al., ). Rotaviruses cause acute dehydrating diarrhoea in various hosts, including children and young animals (Jiang, Liu, & Tan, ).…”

Inter-laboratory study to characterize the detection of serum antibodies against porcine epidemic diarrhoea virus

“…Panel 2 included 8 sera collected in DK from experimentally infected pigs at either 14 or 28 days post inoculation (dpi) with either the early European (Br1/87 strain) or a recent "non-INDEL" US strain of PEDV (described in detail by Lohse et al, 2016).…”

“…The presence of anti-PEDV antibodies in sera was determined (as in Lohse et al, 2016) using an "in-house" blocking ELISA (analogous to that used for PRRSV (Sørensen et al, 1997)) using antigen prepared from PEDV (Br1/87, closely related to CV777)infected Vero cells. Briefly, Vero cells were infected with the Br1/87 strain of PEDV and after 24-48 h, when CPE was apparent, the cells (and medium) were frozen.…”

“…A further round of testing was performed on a second panel of 8 sera that were collected at either 14 or 28 dpi from animals that had been experimentally infected with either the European Br1/87 strain of PEDV (pigs 4 and 5) or with a recent US strain (a non-INDEL strain from Iowa) of PEDV (pigs 12 and 15). These experimental infections have been described previously (Lohse et al, 2016). The results from the testing of these sera, using the different assays, are shown in Table 2.…”

“…The PEDV can be identified by RT-PCR (e.g. Kim et al, 2007;Chen et al, 2014) in faecal or intestinal samples from acutely infected animals and a low level of viremia has also been observed in serum from acutely infected pigs (Jung et al, 2014Lohse et al, 2016). However, the virus is only present in infected animals for a limited period (typically less than 1 month, see Lee, 2015) while the serological response can be expected to be much longer lasting (Crawford et al, 2015).…”