Study on Evaluation of Immune Response to Enterotoxaemia Vaccine in Sheep Reared Under Experimental and Field Conditions by Using ELISA

The immune response in vaccinated animals is measured to fix the due date of booster vaccinations. The seromonitoring can be done by using serological tests, among them ELISA is more specific and sensitive. So the present work was aimed to study on evaluation of immune response in sheep vaccinated against ET by using ELISA. Immune response to enterotoxaemia vaccine (ET) was evaluated in sheep reared under laboratory and field conditions using enzyme-linked immunosorbent assay (ELISA). Under experimental condition, six sheep were vaccinated with booster dose on 14th day and evaluated for immune response; however in field conditions, serum samples from 386 ET vaccinated sheep (139 from organized farms and 247 from unorganized sector of Andhra Pradesh) were evaluated for protective antibody titre using ELISA. Highest protective titre was recorded in sheep reared under experimental condition; on day 30 after vaccination followed by gradual decrease up to day 90. Immune responses of sheep maintained under rural conditions were found to be low when compared with sheep maintained under experimental/laboratory conditions. The protective titers were maintained up to 3 months in sheep maintained under village conditions whereas up to 4 months in those maintained in experimental conditions. So, it can be concluded that good managemental practices along with booster vaccination of ET in farms could evoke better immune response in sheep against ET.