Intestinal protection against challenge with transmissible gastroenteritis virus of pigs immune after infection with the porcine respiratory coronavirus

An infection of pigs with the porcine respiratory coronavirus (PRCV) induces antibodies which neutralize the enteropathogenic transmissible gastroenteritis virus (TGEV) and PRCV to the same titre. In the present study, 10-week-old seronegative pigs (n = 8), pigs immune following TGEV inoculation (n = 4) or pigs immune following aerosol (n = 8) or intragastric inoculation (n = 4) with PRCV were challenged with TGEV. Whereas TGEV-immune pigs were completely protected against challenge, all PRCV-immune pigs showed serological evidence of TGEV replication. Nevertheless, the aerosol or intragastric inoculation with PRCV primed the humoral immune system against TGEV and the TGEV challenge induced a secondary antibody response in most PRCV-immune pigs. Furthermore, all PRCV-immune pigs showed a decrease in the duration of the excretion of infectious TGEV (0–4 days) in comparison with the duration of the virus excretion by seronegative pigs (5–6 days).