Bovine mycoplasmal mastitis is economically important, because it is easily spread in the herd, causes severe decrease of milk production, and affected cows recover with difficulty. Although several mycoplasmal species are associated to bovine mastitis, M. bovis is the most important agent. For the control of bovine mastitis caused by Mycoplasmas, the development of effective vaccines and diagnostics are essential. In this study we evaluated the applicability of recombinant surface variable protein A (VspA) of M. bovis as the candidate of vaccines and diagnostics. The genomic DNA encoding full size VspA from four strains of M. bovis, type strain and three strains isolated from bovine mastitis, were amplified by polymerase chain reaction and cloned into histidine hexamer fusion protein expression vector plasmid. The recombinant VspA proteins of the four strains were purified from the recombinant Escherichia coli lysate. The purified VspA proteins reacted well not only with rabbit antiserum immunized with whole cells of M. bovis but also with sera collected from cattle naturally infected with M. bovis which showed respiratory disorder, in immuno-blotting analysis and in indirect enzyme-linked immunosorbent assay. The rabbit antisera against purified VspA proteins also inhibited the adherence of live M. bovis cells to the surface of mucous membranes of calf trachea by in vitro assay. These results suggested that the recombinant VspA protein would be a good candidate for vaccines and diagnostics for the control of diseases, such as mastitis, respiratory disease, and arthritis, caused by M. bovis infection. (Quality Control Division, Department of Biologicals Production TEL+ 81-29-838-7874)
Reference:
Imada et al. (2002) Jap. J. Mycoplasmol. 29:39-41 (in Japanese).
