Safety and long term efficacy of Porvac®, a subunit vaccine against classical swine fever
Keywords:
classical swine fever, vaccine, safety, efficacy, colostral antibodies, PorvacAbstract
Introduction. Porvac is a subunit vaccine against Classical Swine Fever (CSF), whose active principle is the chimeric protein between the E2 antigen and the molecular adjuvant CD154. Its ability to prevent transplacental transmission and to protect 7 days after one dose was demonstrated. This paper summarizes the safety, immunogenicity and efficacy studies of this vaccine at different ages and handling conditions. Methods. The vaccine was produced under GMP conditions. Dubroc x Yorkshire crossbreed swine were used in all experiments. The general immunization schedule consists in two immunizations on days 0 and 21 by the intramuscular route in the neck. The neutralizing antibody response was measured by the NPLA assay. Viral challenge experiments were conducted in controlled areas. Results and Discussion. Porvac was safe and well tolerated in piglets and pregnant sows. No local or systemic reactions were documented. The number of offspring, their weight and survival in vaccinated sows was similar to unvaccinated controls. Different immunization schedules with Porvac induce protective neutralizing antibodies (NAb). The titers of maternal derived antibodies (MDA) in the offspring of Porvac or Attenuated Life vaccine and Porvac vaccinated sows were higher than 1:200 up to at least 8 weeks of life. The MDA were able to protect piglets from a lethal viral challenge. Those MDA did not interfere with Porvac vaccination of the piglets 15 days after birth or more. Finally, Porvac induced NAb titers persisted during 9 months above 1:2000 and were still protective against the viral challenge. Conclusions. The results demonstrate the capacity of Porvac to be safe and to induce robust and long term immunity through all the life of the animals, without immunological windows.Downloads
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