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A Streptococcus agalactiae R protein analysed by polyclonal and monoclonal antibodies
Author(s) -
BEVANGER LARS,
KVAM AUGUSTA IRENE,
MÆELAND JOHAN A.
Publication year - 1995
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1699-0463.1995.tb01430.x
Subject(s) - streptococcus agalactiae , polyclonal antibodies , monoclonal antibody , microbiology and biotechnology , streptococcus , antibody , monoclonal , biology , virology , bacteria , immunology , genetics
Unexpected cross‐reactivity between two Streptococcus agalactiae (GBS) isolates formed the basis for purification of a GBS protein called the Ra antigen, and raising of murine monoclonal antibody (MAb) against Ra. The Ra protein was resistant to trypsin digestion, susceptible to pepsin digestion, formed a ladder‐like pattern of lines with a periodicity of ˜8 kD on immunoblotting, was surface localized in GBS strains, and was variably expressed by GBS. These characteristics provided evidence that the Ra antigen belonged to the R proteins of GBS. By testing of reference GBS isolates and antiserum, including an anti‐R4 protein serum, cross‐reactivity was recorded consistent with the assumption that Ra is a R4 protein. The Ra/R4 protein also showed cross‐reactivity with a previously described GBS protein called protein Rib (J. Exp. Med. 177 : 1593–1603, 1993). Several characteristics of the Ra/R4 protein were similar to those of the GBS protein c α , but the two proteins showed no cross‐reactivity. The anti‐Ra/R4 MAb has proved useful in serosubtype determination of GBS of known serotype and should be a valuable tool for studying the immunobiological function of antibodies targetting the surface‐localized Ra/R4 protein.