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Expression of Virulence‐Associated Antigens of Rhodococcus equi Is Regulated by Temperature and pH
Author(s) -
Takai Shinji,
Fukunaga Nariaki,
Kamisawa Kei,
Imai Yumiko,
Sasaki Yukako,
Tsubaki Shiro
Publication year - 1996
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1996.tb01113.x
Subject(s) - rhodococcus equi , virulence , biology , microbiology and biotechnology , antigen , genetics , gene
We recently reported that there are two different virulence‐associated antigens correlated with virulence levels in Rhodococcus equi isolates from AIDS patients: virulent R. equi that kills mice with 10 6 cells expresses 15‐ to 17‐kDa antigens and intermediately virulent R. equi that kills mice with 10 7 cells expresses a 20‐kDa antigen. Environmental parameters were evaluated for their effects on the expression of these virulence‐associated antigens in virulent R. equi strains by immunoblotting using monoclonal antibodies in this study. Expression of these two virulence‐associated antigens of R. equi was regulated by pH and temperature; the antigens were produced maximally when the isolates were grown at 38 C and pH 6.5, but were not produced when grown at 38 C and pH 8, nor at temperatures below 30 C. The 20‐kDa antigen was found to be located on the cell surface, as were the 15‐ to 17‐kDa antigens, and showed susceptibility to proteolysis by trypsin. These results indicate that expression of the virulence‐associated antigens of R. equi is dependent on the environmental conditions.