[Evaluating protective effect of inactivated bivalent vaccine prepared from Listeria monocytogenes serotypes 1/2a and 4b for listeriosis control in sheep. [Doctoral dissertation]] | Ispitivanje efikasnosti inaktivisane dvovalentne vakcine pripremljene od serotipova 1/2a i 4b Listeria monocytogenes u kontroli listerioze kod ovaca. Doktorska disertacija

Listeria monocytogenes is a causative agent of listeriosis, antropozoonotic disease, and infect more than 50 species of animals and humans. In this doctoral thesis protective effect of two experimental, inactivated bivalent vaccines (vaccines A and B) were evaluated. Vaccines were prepared of L. monocytogenes serotypes 1/2a and 4b, which are the most frequent in our and surrounding epidemiological areas. Vaccine A consists of whole bacteria L. monocytogenes cells, inactivated by 0.4% formaldehyde and aluminum hydroxide as a carrier. Vaccine B has 0.1% saponine in addition to ingredients of vaccine A. Evaluation for our experimental vaccines were performed in 40 lambs. Animals were divides in four groups (n=10) and each group has one negative control animal. The first group of lambs was vaccinated by subcutaneously administration of 2.5 ml x 10**6 cfu/ml vaccine A. The second group of lambs was vaccinated by subcutaneously administration of 5.0 ml x 10**6 cfu/ml vaccine A. The third group of lambs was vaccinated by subcutaneously administration of 2.5 ml x 10**6 cfu/ml vaccine B and the fourth group of lambs was vaccinated by subcutaneously administration of 5.0 ml x 10**6 cfu/ml vaccine B. After 14 days, boosterisation of all animals was done. In order to evaluate the immune response, blood were sampled every 14 days, during the next 6 months period. Antibody titres were determined by microaglutitation (MAT) and complement fixation tests (CFT). Comparative analysis of antibody titres, induced by vaccines A and B, show that vaccine B with 0.15 sponine significantly increased the level of antibody titres. The quality of immune response was significantly impacted by a total bacteria number and vaccine dosages. The established antibody titres were much higher after application of 5.0 ml x 10**6 cfu/ml, rather than 2.5 ml x 10**6 cfu/ml dosage. Antibody titres were significantly higher after boosterisation and protective levels cold be detected in sera of vaccined animals 6 months later. Therefore, it is strongly recomended to perform boosterisation two weeks after vaccination. Bivalent vaccine with 0.1% saponine (vaccine B) in 5.0 ml x 10**6 cfu/ml dosage shows a protective effect after challenge with L monocytogenes infection. The protective levels of antibody were 1:80 and 1:16, determined by microaglutitation (MAT) and complement fixation test *CFT), respectively.