S.AUREUS IS ONE OF THE MAJOR CAUSES OF BOVINE MASTISIS. THE LONG TERM AIM OF THIS WORK IS TO IDENTIFY THE VIRULENCE DETERMINANTS IN S. AUREUS FROM WHICH A VACCINE AGAINST MASTITIS CAN BE MADE.
Antibiotic therapy is largely ineffective and no adequate vaccine is available. S aureus expresses a variety of factors (eg toxins, enzymes, surface components) that might be important in infection and could be components in a future vaccine.
Techniques for contructing site specific mutations in S aureus were devised. Mutants defective in alpha-toxin, beta-toxin and protein A were constructed and were shown to be less virulent than the wild type in the mouse mastitis infection model, providing clear evidence that these factors are important in pathogenesis. Expression of alpha-toxin caused mortalities in infected animals and was the major cause of damage to cells (including phagocytes). Expression of beta-toxin promoted growth in vivo, whereas protein A helped bacteria avoid being phagocytosed. In contrast, coagulase deficient mutants were still virulent.
THE SPECIFIC AIM OF THIS PROJECT IS TO CLONE AND TO INACTIVATE BY REPLACEMENT MUTAGENESIS THE GENES SPECIFYING PROTEIN A, COAGULASE AND B-HAEMOLYSIN PRODUCTION BY S. AUREUS.
THE VIRULENCE OF THESE MUTANTS WILL BE ASSESSED IN MAMMARY GLAND OF THE MOUSE (THIS PART TO BE DONE BY A.J.BRAMLEY, COMPTON).
Funding SchemeCSC - Cost-sharing contracts
RG16 0NN Newbury