PRIOR INFECTION OF NURSERY-AGE PIGS WITH PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS DOES NOT AFFECT THE OUTCOME OF TRANSMISSIBLE GASTROENTERITIS VIRUS CHALLENGE

Thirty-six specific-pathogen-free pigs were weaned at 2 weeks of age a nd separated into 4 treatment groups (A-D, 9 pigs/group). Treatment gr oups B and D were infected with porcine reproductive and respiratory s yndrome virus (PRRSV), whereas groups A and C remained uninfected. Two weeks later, 1 pig from each group was necropsied to assess gross lun g involvement, and then the remaining group D PRRSV-infected pigs and the group C uninfected pigs were challenged at 4 weeks of age with tra nsmissible gastroenteritis virus (TGEV) to determine if prior infectio n with PRRSV increased the severity of TGEV disease after challenge. O ne hundred percent morbidity but no mortality occurred in pigs followi ng challenge. Clinically, pigs of both groups C and D were similar in terms of onset and severity of diarrhea. The serum antibody response t o TGEV and the amount and duration of TGEV shedding after challenge wa s similar for both groups. Only a few pigs in each group had a transie nt fever postchallenge, and both group C and group D pigs began to rec over and to gain weight at or near the end of the first week postchall enge. It was concluded that the clinical course of TGEV disease was no t markedly affected by infection of pigs with TGEV 2 weeks after they had been infected with PRRSV.