Data on changes of infectious titer of Porcine Reproductive & Respiratory Syndrome (PRRS) virus depending on variability of cultivation conditions was analyzed in the conditions of the Republic of Belarus. There were determined the regimes of cultivation which made it possible to minimize the terms of virus containing material production up to 3 days. The following factors influenced the infectious titer of PRRS: adaptation to cell culture; completeness of cell culture monolayer; number cells moving into stage of logarithmic growth; infectious dose of virus; storage duration; usage intensity.

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

Research results showed that in the conditions of correct organization and application of technological methods of livestock breeding and feeding it was possible to achieve high livability rate of sheep and lambs up to 90%. Also it was possible to get a substantial break of infection chain of many sheep diseases (especially those which had a respiratory nature). Research results showed that simultaneous application of convalescent-phase serum against sheep acute respiratory diseases, as well as Nitox 200 and Invamek for treatment of sheep and especially 2-3 month old lambs with respiratory infectious diseases promoted the recovery of 80-100% of animals.

In the conditions of the Republic of Belarus there was produced a trial series of hyperimmune serum against livestock animals colibacillosis and there was realized the quality control of the analysed biological preparation. Research results proved that the developed serum was sterile, safe and had high immunogenetic activity. In course of quality control there were considered the following indexes: determination of physiognomy, colour, presence of visually accessible particulate matters; determination of safety and harnfullness; determination of activity; determination of concentration of hydrogen ions; determination of sterility; determination of serum volume in consumption package. For serum production there were used strains E.coli O9, O78, O0, O117, O26, O139, O15, O41, O55, O115, O141, O8, K88, K99, F41, 987P. For the production of trial series there was realized cultivation of Escherichia on the special nutritive media. There used bulls as serum producers

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

Analysis of the epizootological situation in infectious diseases in the world and the Republic of Belarus was presented. The prevention and eradication control strategy of mentioned diseases in Belarus was defined. In Belarus there was stated no cases of special danger infectious diseases of cattle: bovine spongiform encephalopathy; highly pathogenic poultry flu; aphthous fever; since 1982 - Bang's disease; since 1980 - Newcastle disease; since 1999 – anthrax. Preventive maintenance of 30 infectious diseases was based on application of specific prophylaxis.

Usage of biological preparation of high antibacterial activity allows to decrease the air pollution by bacteria of colon bacillus group at 25-100%, increase productivity at 17-67 g, safety – at 0,4%, resistance, protein metabolism, protein fractions and some other indices (lysozyme and betalysine activity, leucocytes, erythrocytes, hemoglobin, calcium, phosphorus, iron, magnesium, AST, ALT, urea, cholesterol, bilirubin and glucose)

Analysis of manifestation of chlamydial infection of cattle in the conditions of forage affect with mycotoxins was realized in the conditions of the Republic of Belarus. Research results showed that chlamydial infection proceeded in association with aflatoxin, T-2 toxin, deoxynivalenol, zearalenone and ochratoxin. In course of the biochemical analysis there was noted the lowering of carotene on 23%, and vitamin A – in two times; also there was slight lowering of alkaline reserve. The obtained data proved the substantial changes in content of sub-populations of lymphocytes in cow blood in dry and postnatal period. During the immunological study of immunoglobulins in blood serum of cows sick with postpartum chlamydial endometritis it was revealed that titre of immunoglobulin A was on 31% higher. Level of immunoglobulins G and M differed slightl

There were presented data on etiology, specific prophylaxis and treatment of the most widespread infectious diseases of fishes in the Republic of Belarus: aeromonosis, pseudomonosis, swim bladder inflammation (air bladder disease), viral branchionecrosis. For the preparation of highly efficient specific medical and veterinary preparations it was recommended during the outbreaks of fish diseases to allocate the local pathogens on the basis of which it was recommended to produce vaccines both for perinatal and immersion administration for their wide use both for commodity fishes and for different ages and categories

The information on necessity of carrying out of monitoring and purposeful scientific research on studying of infectious diseases of wild animals in hunting farms of the Republic of Belarus was presented in order to lower their negative influence on state of a population of resource species of wild animals. On the territory of Belarus in the studied wild animals there were stated 42 infectious diseases, including 36 ones which were the reasons of death of valuable hunting and fur-bearing animals. The greatest threat from infectious diseases was represented by rinderpest, pasteurilosis, salmonellosis, furiousness, necrobacillosis, listeriosis, botulism, tuberculosis, pseudorabies, the Siberian ulcer and hoof-and-mouth disease. Many diseases represent danger to human beings, the other lead to a various degree losses for the hunting economy of the country