The Journal of Medical Microbiology, Vol 15, Issue 2 153-162, Copyright © 1982 by Society for General Microbiology
Preparation of specific antisera to the opacity factors of group-A streptococci
C. A. Fraser
Type-specific antibody to the opacity factor (OF) of group-A streptococci
can be demonstrated in human sera but the multiplicity of antibodies to
different serotypes limits their usefulness in anti-OF typing. The antibody
response in rabbits is inconsistent; only 61 of 138 (44%) of rabbit anti-M
sera tested contained OF antibody. Of these only about half had titres of
greater than 16, and usable sera to only 11 of 23 OF-positive serotypes
were obtained. On the other hand good anti-OF sera (titres greater than 16)
to 27 of 28 serotypes resulted from the interperitoneal and subcutaneous
inoculation of heat-killed whole-cell vaccines in guinea-pigs and the
frequency of response in groups of animals given injection of the same
vaccine was 100% for all but three serotypes. Antibody response was not
obtained with M-type 13. A comparison of routes of inoculation for M-type
25 showed that the subcutaneous route alone could probably be used in the
routine production of anti-OF typing sera. Use of the set of 27 sera in
OF-inhibition tests confirmed the remarkable specificity of OF antigens and
their parallelism with M-antigen specificity, with the exception fo a
reciprocal cross reaction between M-type 61 and provisional type PT3875.
