Resposta vacinal à proteína recombinante EMA-2 de Theileria equi em éguas prenhes e seu reflexo no neonato

Abstract

The aim of this study was to evaluate the dynamic of the humoral immune response to recombinant EMA-2 to T. equi in pregnant mares, as well the transfer of passive immunity to the foal. Equine piroplasmosis, caused by T. equi, has severe economic and sanitary international impact. Pregnant mares infected can lead to abortion and neonatal damage, which makes the neonatal period critical for this disease. The vaccine was produced through cloning the EMA-2 expression gene and expressed in Pichia pastoris, and aluminum hydroxide was used as adjuvant. Eighteen pregnant mares were used, which were divided in Control and Vaccinated that received three doses of rEMA-2 starting at 300 days of gestation. The 18 foals delivered both groups was evaluated until 6 months of life with respect the antibodies obtained through passive immunity. On 2nd month of life, a grouo of foals received vaccinal scheme with EMA-2, looking evaluate the dynamic of active immune response. Indirect ELISa was the chosen test for all samples. The rEMA-2 vaccine developed humoral immunity in vaccinated pregnant mares that showed an increment on antibody levels of 2.3 times when comparing to the baseline values. Concentration of vaccinal antibodies in colostrum and serum of foals delivered by vaccinated mares showed that antibodies were transfered to foals through passive immunity. Foals that received vaccinal scheme after 2nd month of life showed an increment on antibody levels of 8.3 times when comparing to the baseline values. The vaccine scheme with rEMA-2 was able to stimulate the humoral immunity in pregnant mares. Vaccinated mares concentrated vaccine immunoglobulins in colostrum. Foals delivered by these mares had an increment in serum levels of vaccine antibodies after the first nurse.