Vaccination of Dams Increases Antibody Titer and Improves Growth Parameters in Finisher Pigs Subclinically Infected with Porcine Circovirus Type 2

Abstract

Porcine circovirus type 2 (PCV2) is the obligate infectious agent in postweaning multisystemic wasting syndrome (PMWS) of pigs. To control PMWS, we vaccinated dams at 4 and 2 weeks before pregnancy and again in the 12th week of gestation with an inactivated PCV2 vaccine (Circovac). Two producer farms run under the control of Swiss Swine Health Organization were selected for the experiment. Previously, in one farm PMWS was diagnosed on pigs after weaning, whereas in the other farm, pigs wasted during the fattening period. For the experiments 113 dams were randomly vaccinated, and 111 dams were sham injected. Vaccination increased serum antibodies in dams 3-to 9-fold, accompanied by serum antibody titer increases in their offspring. In the sixth week of life, progeny from vaccinated dams had about the same IgG antibody titers as progeny of unvaccinated dams at the third day of life. In sera of vaccinated dams only low concentrations of PCV2 DNA were detected, and no progeny developed PMWS. Interestingly, at day 56 four progeny of unvaccinated dams tested positive for anti-PCV2 IgM antibodies, indicating a primary infection with PCV2. Of economic importance is the observation that progeny of vaccinated dams had a significantly higher daily weight gain in the fattening period (farm X, ؉51 g/day; farm Y, ؉30 g/day) and thus a shortened fattening period of about 6 days compared to progeny of controls. To our knowledge this is the first demonstration of subclinical circovirus infection and its effects on growth performance of fattening pigs by vaccination of dams.

A commercial porcine circovirus (PCV) type 2a-based vaccine reduces PCV2d viremia and shedding and prevents PCV2d transmission to naïve pigs under experimental conditions

“…In 2011, Circovac® was also licensed for use in piglets using the same vaccine preparation but at a lower dose compared to sows (0.5 ml versus 2 ml). In field and experimental studies, Circovac® has been shown to be effective at protecting pigs against the effects of PCV2a and PCV2b challenges when used in sows or piglets [7], [33], [34].…”

“…Porcine dermatitis and nephropathy syndrome (PDNS) has also been linked to PCVAD [4], [5], although definitive experimental proof is still lacking. In addition to PCVAD, PCV2 infection can result in subclinical disease for extended periods of time, which can have a varying impact on pork production [6], [7]. Non-specific clinical signs including reduced weight gain associated with subclinical PCV2 infection are thought to occur due to the effect of PCV2 on the immune system [8].…”

T-cell reprogramming through targeted CD4-coreceptor and T-cell receptor expression on maturing thymocytes by latentCircoviridaefamily member porcine circovirus type 2 cell infections in the thymus

“…42 Nine or 10 consecutive blood samples were taken from each pig over 31 or 52 days to determine the antibody content and viremia.…”

Antibody Titers from Finisher Populations with Persistent/Latent PCV2 Infection Before, During and After the PCV2-SD Epizootic

“…Various studies have found elevated anti-PCV2 antibody concentrations after vaccination against PCV2 [7,11], significantly shorter and milder viremia [10], and a higher proportion of CD4(+) CD8(+) IFNγ(+) lymphocyte subsets in vaccinated piglets [12]. Nevertheless, elevated antibody titers that are due to vaccinations of piglets against PCV2 do not last until finisher stage [13].…”

“…Two hundred randomly selected finisher serum samples from each of the three time periods were obtained from the serum bank of the Institute of Virology and Immunology (IVI), Mittelhäusern, Switzerland, and were analyzed via competitive ELISA (SERELISA® PCV2 Ab Mono Blocking Systems, Synbiotics Corporation Europe SAS, Lyon) for the presence of PCV2-specific antibodies [11].…”