Serological properties of bovine viral diarrhoea virus (BVDV) isolates from Turkey and determination of immunological levels produced by BVDV vaccines used in Turkey against local isolates


Thesis Type: Doctorate

Institution Of The Thesis: Uludağ Üniversitesi, Turkey

Approval Date: 2014

Thesis Language: Turkish

Student: GİZEM ALPAY

Supervisor: KADİR YEŞİLBAĞ

Abstract:

Bovine viral diarrhoea virus (BVDV) causes an infectious disease which seen in worldwide. By different studies many distinct subtypes were identified in both genotypes. Current studies showed that BVDV -1l is predominant subtype in Turkey. The first aim of this study was to determine serological relations between the prevalent subtypes in the Turkey. For that purpose polyclonal antiserums were obtained by immunization of sheep with 6 inactivated virus strains belonging to BVDV -1 subtypes (BVDV-1a, -1b, -1d, -1f, -1h -1l) and were used for cross-neutralization tests. Neutralizing antibody titers with using different antiserums are; 1:320, 1:285, 1:320, 1:226, 1:1280 and 1:1015 respectively. The degree of serologic diversity varied markedly between tested subtypes. However it is exhibited that subtype BVDV-1f was significantly diverse, BVDV -1h and BVDV-1l were closely related with the other tested subtypes especially subtypes found in common vaccines for BVDV. The second goal of this study was to investigate the level of virus neutralizing (VN) serum antibodies rised against Turkish isolates by BVDV vaccines which is in the market in Turkey. For that purpose 3 experimental group of cattle, each including 5 animals, were immunized with a seperate BVDV vaccine. Blood samples were taken 6 times with 15 day intervals and used for determination of neutralizing antibody titers against 11 BVDV local strains. However all three vaccines induced neutralizing antibody titer against many of antigenically diverse BVDV-1 strains (1:272 – 1:835) seen in Turkey, antibody titers against BVDV-2 strain were lower. Although antigenic differences of BVDV-1f subtype was indicated in the first experimental scheme of this study, antibody titers generated by all three vaccines for this subtype were higher than recomended protection levels (1:256). When geometrical means of neutralizing antibody titers among three vaccine groups were compared, it was detected that the monovalent vaccine sitimulated titers higher than multivalent BVDV vaccines.