Efficacy of an Inactivated Porcine Parvovirus (PPV) Vaccine under Field Conditions

Abstract

Dose response experiments were carried out by vaccinating groups of seronegative gilts (7 months of age) and groups of gilts with residual maternal serum antibodies to PPV (5 months of age). PPV vaccines containing different amounts of inactivated virions were used. Vaccinations were carried out twice with 3 weeks intervals. It was demonstrated, that a single vaccination even with a vaccine with low antigen content elicited an antibody response to PPV in seronegative gilts. The titer values increased after the 2nd vaccination.

When the gilts had residual maternal serum antibodies at the time of vaccination the antibody response was generally lower. In some animals the titer values decreased after the 1st vaccination, but except for 2 gilts vaccinated with vaccines with a low antigen content an increase of titer values followed after the 2nd vaccination. During a field trial performed in a herd with enzootic PPV infection all the gilts were vaccinated with PPV vaccine before mating. Blood samples were examined for HI antibodies before and after vaccination and at weaning time of each of the resulting 5 litters. In total 24 batches of gilts comprising 326 animals mated during a 2 year period were examined. It was demonstrated, that the applied vaccine preparations used under field conditions gave a relatively high and long lasting antibody response, even when the gilts were vaccinated as early as at about 5 months of age.

Sammendrag

Der præsenteres resultater af dosisrespons forsøg udført ved vaccination af grupper af seronegative sopolte og grupper af sopolte med maternelle antistoffer mod PPV. Der blev anvendt PPV vacciner med forskellig antigenindhold. Der blev foretaget 2 vaccinationer med 3 ugers mellemrum.

I seronegative dyr gav en enkelt vaccination et antistofsvar selv med vaccine med lavt antigenindhold. Titerværdierne steg efter anden vaccination. Hos dyr med maternelle antistoffer var antistofsvaret generelt lavere. I nogle tilfælde faldt titerværdierne efter første vaccination, men med undtagelse af 2 dyr vaccineret med vaccine med lavt antigenindhold fulgte en titerstigning efter anden vaccination.

I et markforsøg i en besætning med enzootisk PPV infektion blev alle sopolte vaccineret med PPV vaccine før løbning. Der blev taget blodprøver før og efter vaccination og ved fravænning af de følgende 5 kuld. I alt blev 24 hold omfattende 326 dyr undersøgt. Det blev demonstreret, at Vaccinen under de gældende forhold gav et relativt højt og langvarigt antistofsvar, selv når sopoltene blev vaccineret så tidligt som i 5 måneders alderen.