Development of a vaccine preventing parvovirus-induced reproductive failure in pigs

An inactivated porcine parvovirus (PPV) vaccine for the prevention of PPV-induced reproductive failure in pigs was developed, using virus grown in cell culture, inactivated with beta-propiolactone and adjuvanted with aluminum hydroxide. The vaccine was tested for safety by subcutaneous injection into pregnant gilts. There were no signs of abnormal reactions nor evidence of PPV infection in the gilts or their foetuses when they were sacrificed 6 weeks after vaccination. To demonstrate that the vaccine was immunogenic, pigs were immunised either once or twice with 4 weeks between doses. Resulting antibody titres (haemagglutination inhibition - HAI) ranged from less than 8 to 64 (geometric mean of 30) after one dose of vaccine, and from 128 to 512 (geometric mean 256) after two doses. To demonstrate that the vaccine was protective, antibody-negative gilts were vaccinated twice, with 4 weeks between doses, joined after the second dose, and were then infected with virulent PPV 40 to 50 days after joining. In litters from 10 vaccinated gilts, none of 93 foetuses showed evidence of PPV infection. In contrast, in litters from two unvaccinated gilts, all 13 foetuses showed evidence of PPV infection and 10 of these were mummified. The average number of live piglets per litter was 9.2 from vaccinated gilts and 1.5 from unvaccinated gilts. The vaccine was therefore considered to be effective in preventing PPV reproductive failure in susceptible gilts.