The level of antibody by ELISA,immunsosuppressive effect baes on the response of birds to Newcastle disease vaccination and damage to bursa of Fabricius by IBD vaccination were studied. The efficacy of six different IBD vaccination schedules were studied using intermediate and intermediate plus strains of vaccines either alone or in combination. In vaccinated groups, the sero-conversion of the vaccine virus was noticed during fourth week, reaching to the peak between eight to twelve weeks of age in different groups. Afterwards, there was a gradual decrease in the titres, by the end of 20th week (maximum period tested). There was no significant difference in the titres of different treatment groups. However, all the groups showed titres above protective level during the entire period of study. There was significant difference in bursa body weight (B-BW) ratios of vaccinated groups in comparison with control group. Histopathological studies of bursal sections revealed depletion of lymphoid follicles, presence of cystic spaces, edema and hemorrhages. The birds vaccinated with hot strain of IBD vaccine showed metaplastic changes, presence of foam cells with pronounced interfollicular fibrosis. The bursal scores were maximum in the groups vaccinated with hot strains of IBD vaccines.

Immunomorphological changes in young hens vaccinated with an associated inactivated emulsion vaccine against bursal disease, infectious bronchitis and Newcasle disease was realized in the conditions of the Republic of Belarus. Replacement young hens of 130-158 days old were divided into 2 groups with 200 head in each according the analogue principle. At the age of 130 days old the first experimental group of chickens was immunized against bursal disease, infectious bronchitis and Newcasle disease with a liquid inactive emulsion vaccine (produced in the republic of Belarus) in dose of 0,5 ml intramuscularly. In course of the experiment chickens from each group were killed on the third, seventh, fourteenth, twenty-first and twenty-eighth days. For the analysis of immunomorphological reaction there were tested tissue pieces from the places of vaccine administration, as well as thymus, bursa of Fabritius, lien, cecal tonsils and Garder's gland. Research results showed that in tissues in places of the vaccine administration there were developed hemorrhages, serous inflammatory edema, necrobiosis and necrosis of muscular fibers, inflammatory cellular infiltration, and moderate plasmocytic reaction. At a later stage at the places of damaged structures there was noted the development of granulation tissue with presence of some lymphoid nodules. In response to vaccination in the central organs of poultry immunity there was stated the sinuated changes of morphological indexes. Immunization of chickens against infectious bursal disease, infectious bronchitis and Newcasle disease promoted the increasing of absolute weight of lien, activation of blastic and plasmocytic reaction in bursa of Fabritius and lien and did not render substantial influence on immunomorphological indexes of cecal tonsils and Garder's gland

Morphological indexes in immune system organs of piglets which were vaccinated which were immunized by SPS vaccine (against salmonellosis (Salmonella), pasteurellosis (Pasteurella) and streptococcus) in combination with immunostimulative drugs and without them were studied in the conditions of the Republic of Belarus. Piglets of the first group were vaccinated against salmonellosis, pasteurellosis and streptoccocusis by SPS vaccine. Piglets of the second group were vaccinated by SPS vaccine in combination with vitamin C. Piglets of the third group were vaccinated by SPS vaccine with immunotstimulant sodium thiosulphate. The fourth (control) group of animals was administrated with normal saline. Animals were immunized twice, intramuscularly with 7 day interval and in dose 4 ml (primary), 5 ml (secondary). Vitamin С was added in dose 0,05g per head. Research results showed that immunization by SPS vaccine with sodium thiosulphate and Vitamin С activated the morphological reaction of immune system. Application of Vitamin С and sodium thiosulphate (30% concentration) in combination with SPS vaccine promoted the increasing of lymphoid nudels in lymphodnudus and lien, increasing of plasma cells quantity in 1,3-2,2 times, activation of micro- and macrophage reaction in 1,5-2,8 times in comparison with vaccinated animals

Investigation of immunity of broiler chickens of Kobb-500 cross vaccinated by national associated viral vaccine and foreign (ABIC, Israel; Vitex XXI vek Seva) vaccines against Newcastle disease and infectious bronchitis was investigated in the conditions of the Republic of Belarus. In course of studies there was analyzed the content of immunoglobulin in blood serum, as well as the influence of living vaccines on immunity formation. Research results showed that broiler chickens immunization against Newcastle disease and infectious bronchitis by national and foreign vaccine produced by ABIC company made it possible to increase the phagocytic activity of pseudoeosinophils, bactericidalal and lysozyme activity of blood serum, that proved the activation of nonspecific protection factors. At the same time in blood serum there was stated the increasing of immunoglobulin number in 1,5-3,0 times in comparison with control groups. Economic efficiency of all analyzed vaccines was analyzed

Experimental application of a vaccine against salmonellosis, pasteurellosis, and streptococcosis (SPS) for piglets of 30-35 days was realized in the conditions of the Republic of Belarus. Research results showed that administrationof sodium thyosulphate and vitamin С in combination with SPS vaccine promoted the statistically-valid increasing of preventive properties of blood serum of piglets and increasing of titers of specific antibodies to agents of pasteurellosis and a salmonellosis in 1,3-2 times, as well as increasing in blood serum of quantity of immunoglobulins and to reduction of quantity of globulins.

In the conditions of immunization of swine by experimental produced at Vitebsk Biofactory in the Republic of Belarus vaccines in blood of experimental swine there stated the morphological changes which pointed to formation of immune response.

After immunization of 30-35 day old piglets against a salmonellosis, pasteurellosis and streptococcosis (SPS) with special produced in the Republic of Belarus SPS vaccine in combination with immunostimulant sodium thyosulfate and vitamin C there was observed an activation myeloblastic hemopoiesis and lowering of erythropoeisis.

Morphological and structural changes in bone marrow of piglets which were immunized with produced in the Republic of Belarus SPS vaccine (against salmonellosis (Salmonella), pasteurellosis (Pasteurella) and streptococcus) in combination with immunostimulants and without them were analyzed in the conditions of the Republic of Belarus. Piglets of the first group were vaccinated against salmonellosis, pasteurellosis and streptoccocusis by SPS vaccine. Piglets of the second group were vaccinated by SPS vaccine with vitamin C. Piglets of the third group were vaccinated by SPS vaccine with immunotstimulant sodium thiosulphate. The fourth (control) group of animals was administrated with normal saline. Animals were immunized twice, intramuscularly with 7 day interval in dose of 4 ml (primary), and 5 ml (secondary). Vitamin С was administrated in dose of 0,05g per head. Sodium thiosulfate was administrated in combination with the vaccine in 30% concentration. Alongside with myelogram there were derived formulas of different cell groups of bone marrow: leucoerythroblastic index; intramedullary index of neutrophil maturity; intramedullary index of eosinophile maturity. Detailed myelogram of piglets on the 14-th day after the second immunization was presented. Research results showed that in all groups of vaccinated animals there was noted the activation of myeloblastic hematogenesis and decreasing of erythropoeisis. Piglet immunization was accompanied by strengthening of myeloblastic hematogenesis, increased number of lymphocytes and plasma cells in bone marrow

Research of immune activity of an experimental series of inactivated vaccine against swine pasteurellosis (Pasteurella) with application of adjuvants of Sepptic Montanida ISA 70 and Montanida ISA 206 was realized in the conditions of the Republic of Belarus. In the capacity of water phase there were used serovars A, B, and D Pasteurella multocida. Research results proved the possibility of application of adjuvants of Sepptic company for the development of vaccine against pasteurellosis. The vaccine with the presented adjuvants after its application did not cause after-trouble effects. In course of immunization there was noted the formation long-lived continuous immunity that was proved by high titres of specific anti-bodies in blood serum in all experimental groups of piglets. Single application of the proposed vaccine in doses 2 or 3 ml per animal proved to be effective. Also it was efficient to apply it twice in doses 1 and 2 ml per animal. For the vaccine production it was proposed to use adjuvant Montanida ISA 206 which did not have high reactogenicity

Studying of palatability of bait blisters applied for oral immunization of wild carnivores against rabies was realized in the conditions of the Republic of Belarus by an example of foxes which were administrated with liquid viral vaccines against rabies. Foxes were divided into 5 groups with 8 animals in each. Animals of the first group were immunized with a liquid viral vaccine in blister baits Lisvulpen-VBF which was produced from an attenuate strain of rabies virus SAD-BERN (Belarus). Animals of the second group were immunized with liquid viral vaccine Belvak TM BP produced from the cultural living strain KMIEhV-V101 (Belarus). Animals of the rest three groups were immunized with liquid viral vaccine in blister baits which was produced from a modified strain of a fixed attenuate rabies virus KMIEV-94. Foxes of the forth group were additionally fed with ascorbic acid with baits in the doze of 0,1 g, and foxes of the fifth group were fed with 5 ml immune response modifier Nuklevit. All mentioned blister baits were studied in accordance with the following parameters: bait flavor and attraction to animals; form and size of bait; bait consistency; blister and its size in relation to bait; palatability of bait; degree of damage of bait containing a vaccine; quantity vaccine which was got into animal oral cavity; postvaccinal complication. Palatability of liquid viral vaccines in blister baits Lisvulpen-VBF was 96%, Belvak TM BP - 94%, KMIEV-94 - 80%