Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 1996
Publication Date: N/A
Interpretive Summary: A pseudorabies eradication program is now in progress in the United States to try to eliminate this disease which costs the swine producer and consumer millions of dollars annually. Vaccines are being used in the eradication program to help reduce the losses due to disease and also decrease the spread of the disease. No vaccine has been able to stimulate an adequate immune response in piglets while they are still under the protection of antibodies received from their mother. We vaccinated sows with a virus (vaccinia virus) which carries genes for proteins of pseudorabies virus. Piglets born to these sows nursed and obtained antibodies to the proteins of pseudorabies virus. We were then able to vaccinate the piglets with either conventional pseudorabies virus vaccines or a similar vaccinia virus vaccine which carried a gene for a different protein of pseudorabies virus. With this approach we were able to stimulate an immune response which protected the pigs from illness and decreased the amount of virus the piglets shed into the environment. This vaccine has the potential to protect sows and piglets when they are most susceptible to disease and will work to help further the efforts of the current eradication program. Elimination of this disease will increase profitability of the swine industry, help keep food prices low for the American consumer, and increase the export potential for swine.
Technical Abstract: Three gilts were vaccinated with a NYVAC vaccinia recombinant expressing glycoprotein gD of pseudorabies virus (PRV) (NYVAC/gD). After farrowing, the piglets were allowed to nurse normally to obtain colostral immunity and then were divided into 4 groups, receiving NYVAC/gD, a NYVAC recombinant expressing glycoprotein gB of PRV (NYVAC/gB), an inactivated PRV vaccine (iPRV), or no vaccine. The piglets were vaccinated twice, 3 weeks apart, beginning at approximately 2 weeks of age and later challenged with virulent PRV oronasally. Piglets that received NYVAC/gB or iPRV were the best protected based on lack of mortality, lower temperature responses, decreased weight loss, and decreased viral shedding after challenge. These results indicate effective strategies for stimulating active immune response while still under the protection of maternal immunity.