Although the original US porcine epidemic diarrhea virus (PEDV) has been studied and known to cause mortality in suckling piglets, strains with a different genetic profile have not been studied. To discover whether the spike-insertion deletion (S-INDEL) PEDV strains have similar morbidity and mortality, we inoculated 3-4 day-old conventional suckling piglets with virus. Six litters of age-matched piglets were inoculated with either S-INDEL Iowa106 (4 litters), or original US PEDV PC21A (1 litter, positive control) or medium (1 litter, negative control). After 21-29 days, we challenged the piglets with original US PEDV PC21A to assess cross-protection. After the first virus inoculation, all piglets that received the virus developed diarrhea. The severity of the disease and mortality among the four S-INDEL Iowa106-inoculated litters varied greatly. Compared to original PC21A, piglets euthanized/died from S-INDEL Iowa106 infection had relatively milder disease and more limited intestinal infection. Two of four S-INDEL Iowa106-infected sows and the original PC21A-infected sow showed anorexia and watery diarrhea for 1-4 days. Our results suggest that the disease from S-INDEL PEDV Iowa106 strain was less than from the original US PEDV PC21A strain in suckling pigs, with 100% morbidity and 18% (6/33) overall (0 to 75%) mortality, depending on viral dose. We found that PEDV disease in suckling piglets depends on factors such as the sow’s health and lactation and the piglets’ birth weight. Prior infection by S-INDEL Iowa106 did provide partial cross-protection to piglets inoculated with the original PEDV PC21A strain.
Dr. Qiuhong Wang, Food Animal Health Research Program, OARDC, Wooster, OH, 330-263-3960, 330-263-3744
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