Secreted antigens as virulence-associated markers in Staphylococcus aureus strains from rabbits

Western blot analysis was performed from the culture supernatant of 59 rabbit Staphylococcus aureus strains, classified as high and low virulence strains according to their epidemiological behaviour in commercial rabbitries, bio-, phage- and RAPD-type. Fourteen extracellular antigen bands (A-N) were recognised using sera of rabbits immunised with washed, viable high virulence S. aureus bacteria. Eleven of these bands were found in high virulence as well as in low virulence strains. The band A, approximately 78 kDa, was not seen in any of the 27 high virulence strains, except for one strain which was also typical in other aspects, was detected in all, but one of the low virulence strains. The M and N bands with molecular masses of approximately 29 and 27 kDa, respectively, were recognised in all high virulence strains except for the atypical strain, but in none of the low virulence strains. This indicates that the latter two antigens may be virulence-associated markers for S. aureus strains from rabbits.