Evaluation of Transmissible Gastroenteritis and Porcine Respiratory Coronavirus Immunologic Interaction in Seronegative Pregnant Gilts

Abstract

The primary objective of this study was to determine if Porcine Respiratory Coronavirus (PRCV) sensitized gilts responded to intranmuscular (IM) vaccination with Transmissible Gastroenteritis Virus (TGEV) in a similar fashion as gilts sensitized to TGEV alone. It was demonstrated that pregnant gilts sensitized to PRCV, prior to TGEV vaccination, do not produce significantly higher TGEV serum neutralizing antibody titers when compared with gilts sensitized to either PRCV or TGEV alone, Anti-TOEV IgG and IgA levels were assayed for in post-farrow milks from all gilt groups. Only IgG was detected which indicated a lack of mucosal priming. The second objective of this study was to determine if animals, which have recovered from a TGEV infection, can be infected with PRCV. TGEV antibodies circulating in these exposed piglets prevented PRCV infection as demonstrated by the absence of PRCV shedding during the post-challenge period. It was found that these piglets had an eight-fold boost in TGEV serum neutralizing antibody titers 21-days post PRCV challenge. Piglets that had not been exposed to TGEV significantly shed virus during this same post-challenge period and exhibited a three-fold boost in TGEV neutralizing antibody titer. Piglets that had suckled TGEV immune dams were also, for the most part, protected from PRCV shedding but exhibited no boost in TGEV serum neutralizing antibody titer.