ANTIBODIES LEVELS AGAINST Neospora caninum DURING PREGNANCY IN NATURALLY INFECTED DAIRY COWS

Abstract Neosporosis is one of the major causes of reproductive failure in bovine around the world. The period of gestation, in which the infection or the recrudescence of bradzoites forms occurs and reflects in the antibodies levels, is one of the factors that define pregnancy future. Therefore, this study aimed to determine the serological profile during pregnancy of naturally infected females. To do that, serological samples of 25 Holstain Friesian cows were collected from artificial insemination day until parturition, in monthly intervals. These samples were tested by indirect immunofluorescence for IgG anti-Neospora caninum. Of the 25 animals, only 13 were used in the analysis, because they were seropositive since the beginning or seroconverted during pregnancy. The results showed a gradual increase in antibody levels along pregnancy, more visible at the end of the period. We observed a significant difference in antibodies title between initial and final periods of pregnancy, which suggests the reactivation of bradzoite forms present in tissues during pregnancy. These results reinforce the knowledge of antibodies fluctuation along pregnancy, affected by N. caninum reinfection or reactivation. This serological knowledge is important to Neosporosis pathogeny, epidemiology and diagnostic.