Neutralizing antibody decay and lack of contact transmission after inoculation of 3- and 4-day-old piglets with porcine respiratory coronavirus.

Ten female neonatal piglets were infected with porcine respiratory coronavirus (PRCV) to measure the decay of a specific neutralizing antibody. By 42 weeks after exposure,1 of the gilts was serologically negative (< 5) for PRCV, and by 48 weeks 2 more gilts were serologically negative. These data demonstrate that young mature gilts can be serologically negative, yet they could have been exposed to PRCV. Sentinel pigs were commingled with the PRCV-infected pigs at 8 weeks after exposure, and no virus transmission occurred.