NARASIMHA REDDY, Y(Major)DHANALAKSHMI, KANAND KUMAR, AMANOJ KUMAR, V2017-06-102017-06-102013-04http://krishikosh.egranth.ac.in/handle/1/5810019322THESESABSTRACT : The present study is taken up with a view to study the efficacy of brucella vaccine at reduced dose (5 x 109 to 8 x 109 CFU/dose) through conjunctival route and compare it with conventional standard dose (40 x 109 to 80 x 109) vaccine. Female cattle above 8 months age were selected for the study. Thirty animals were inoculated with reduced dose conjunctival vaccine and ten with standard subcutaneous vaccine using Brucella abortus S19 antigen. The efficacy of vaccine was studied in terms of both humoral and cell mediated immune responses against brucella for a period of 120 days. Humoral immunity techniques consisted of rose bengal plate test (RBPT), standard tube agglutination test (SAT) and indirect ELISA (i-ELISA). Cell mediated immune response was studied by using interferon gamma (IFN-γ) assay after in vitro stimulation of lymphocytes with both S19 and B. abortus 544 as antigens in indirect competitive ELISA (Enzyme Linked Immunosorbent Assay). Of the humoral immunity tests employed for studying the efficacy of vaccines RBPT was least sensitive. It detected 20 to 18.51% positive responders at 21 and 60 days PV in reduced dose conjunctival vaccine group. Similarly it detected 60% and 50% responders on 21 and 60 days PV in standard group. Standard tube agglutination test (SAT) detected more responders against vaccinates than the RBPT. The positive percentage ranged from 26 to 66% among reduced dose vaccine group and 40 to 80% among standard dose vaccine group. I-ELISA was the most sensitive as it detected up to 78.9% responders among reduced dose vaccination group and up to 100% in standard dose vaccinates group. Humoral immune responses declined after 90 days PV. IFN-γ production as indicator of cell mediated immune response in vaccinates was more consistent. IFN-gamma production was observed during the entire period of the trial (120 days). It is concluded that CMI responses are better indicators of immune response to brucella than the humoral immunity.ennullThesis