DYNAMIC OF SPECIFIC HUMORAL RESPONSE AND FREQUENCY OF VARIANTS OF PRRS VIRUS IN THREE FARMS WITH DIFFERENT STRATEGIES OF CONTROL, IN YUCATAN, MEXICO

Abstract

The objectives of this study were to describe the dynamic of specific humoral response and frequency of variants of PRRS virus in three farms with different strategies of control. Thirty pigs in each farm were studied. The animals were sampled and sera were processed by ELISA and RT-PCR real time using Sybr Green technology to detect PRRS virus variants. The mean of S/P value, RT-PCR positive and melting temperature were compared at 21, 49, 77,105 and 160 days of age. The pigs from farm A were positive to the ELISA test at all ages; in farm B pigs were positive at 77, 105 and 160 days of age, and the pigs from farm C were positive at 105 and 160 days of age. Melting curve analysis, showed four different melting times in each farm corresponding to four types of viruses: vaccine virus, inoculum and two wild type viruses. The different strategies used in the farms induced an immune response in most animals. The highest S/P were obtained in farm A. The strategies of control did not avoid the presence of variants of PRRS virus, which might represent a risk for the animal population.