Evaluation of attenuated bovine farcy vaccine; M. farcinogenes in zebu calves using serology, passive immunization and Plaque forming Cell Assay, Sudan.

EL Tigani-Asil¹, T. A; EL Sanousi², S.M.; Aljameel³, A.; Muaz¹, M.A.;Terab¹, N.M.A. and Osman⁴, M.

1: Departments of pathology and microbiology, Faculty of veterinary science University of Nyala,  Sudan.

2: Departments of microbiology and preventive medicine, Fac. of Vet. Medicine, University of Khartoum, Sudan.

3. Department of Pathology, veterinary Research Laboratory, Nyala, Vet. Res. Corporation,Sudan.

4. Central laboratory, Soba, Ministry of Science and Technology, Sudan

*Corresponding Author’s: Email asiltigani@yahoo.com;

Tel: 0129037088.

Accepted 12 June, 2013

Abstract

Aims: The aim of the present study was to prepare an attenuated bovine farcy vaccine and to evaluate its efficacy in zebu calves in South Darfur state, Sudan. Methodology: A total of 59 Mycobacteria isolates from cases of bovine farcy during 2007-2009 in South Darfur State, Sudan. The Isolates were identified by conventional phenotypic tests in comparison to a 16S-23S rDNA PCR assay. M. farcinogenes (MF216) was serially attenuated 10 times 5 times in-vitro and 5 times in-vivo. the 10^th passage was propagated in Souton΄s broth and was considered as a candidate attenuated farcy vaccine (CAFV). The vaccine was tested in zebu calves and evaluated using serological, passive immunization and plaque forming cell assay. Results: Titration of circulatory antibodies induced by the live attenuated farcy strain MF216 in zebu calves using Heamagglutination test detected low antibodies titers after primary vaccination which clearly increased post the booster dose. ELISA cut-off values (P> 0.142) determined in this study also illustrated low circulating antibodies induced by the vaccine. Despite the low level of antibodies 2 of 3 quinea pigs passively immunized resisted challenge with fresh farcy strain MF304. Plaque forming cells (PFCs) were demonstrated microscopically using X40 lens as two cells for one reaction containing 20 μl effectors cells. Conclusion: An attenuated farcy vaccine produced low circulating immunoglobulins in zebu calves which had a significant protective role, hence it passively immunized quinea pig.    

Keywords: Live attenuated Mycobacterium farcinogenes, bovine farcy, Acid fast filaments Darfur, Sudan.