Goblet cell depletion in small intestinal villous and crypt epithelium of conventional nursing and weaned pigs infected with porcine epidemic diarrhea virus.

Intestinal goblet cells secret mucins to form mucus layers critical for maintaining the integrity of the intestinal epithelium. Porcine epidemic diarrhea virus (PEDV) causes watery diarrhea and high mortality of suckling pigs. PEDV mainly infects villous epithelial cells of the small intestine, and infected cells undergo acute, massive necrosis, followed by severe villous atrophy. Conventional 9-day-old nursing pigs [PEDV-inoculated (n=9); Mock (n=11)] and 26-day-old weaned [PEDV-inoculated (n=11); Mock (n=9)] were inoculated orally [8.9 log10 genomic equivalents/pig] with PEDV strain PC21A or mock. We used alcian blue or Periodic-Acid-Schiff staining for the detection of acidic or neutral mucin-secreting goblet cells in the small intestine. We demonstrated that PEDV infection of the nursing pigs at post-inoculation days (PIDs) 1-5 and weaned pigs at PIDs 3-5 led to depletion or significant reduction in the number of goblet cells (and also the number of villous goblet cells normalized by jejunal villous crypt height to crypt depth ratios) in the villi or crypts. These findings coincided with the development of intestinal villous atrophy. By immunohistochemistry, a few PEDV antigen-positive goblet cells were identified in the jejunal or ileal villous epithelium of the infected nursing or weaned pigs. During the early stages of PEDV infection, goblet cell mucins in the small intestine may be decreased, possibly leading to an impaired mucus layer and increased susceptibility to secondary enteric bacterial infection.