A total of 928 pigs from the Swine Teaching and Research Centers at Michigan State
University (MSU) and Kansas State University (KSU) and a Kansas commercial farm
were used during a 3-year study to determine whether circovirus vaccination influenced porcine circovirus type 2 (PCV2) circulation within a herd and could be used
as a tool to eliminate PCV2 from PCV2-positive swine herds. Infection with PCV2
was confirmed in both university herds before circovirus vaccine introduction. After
vaccination implementation, vaccinated barrows from consecutive groups were serially
tested for viremia. Follow-up antibody and growth testing with vaccinated and nonvaccinated
pigs was performed at the KSU farm. In a circovirus-vaccinated commercial
herd, testing of non-circovirus-vaccinated pigs for viremia was completed. Environmental swab samples were collected from facilities at the KSU and commercial farms for
PCV2 DNA detection.
Sera from 0 of 9 MSU vaccinated-cohorts and 3 of 10 KSU vaccinated-cohorts had
detectable PCV2 DNA. From follow-up testing, a PCV2 antibody rise after vaccination was detected for vaccinated pigs with no detectable antibody rise for non-vaccinated pigs. Overall growth rate of non-vaccinated pigs tended (P = 0.07) to increase
compared with vaccinated pigs. Non-vaccinated pigs became PCV2 viremic at the
commercial farm. Viral DNA was detected in the environment of the commercial farm
but not in the KSU facilities.Therefore, circovirus vaccine can affect viral circulation on farms but would need to be
used in conjunction with other management practices to eliminate PCV2 from most
swine populations.
