A study has been made of the properties of soluble antigen in the brains of infant mice infected intracerebrally with the Flury strain of rabies virus.
Soluble antigen is produced at the same time as infective virus, and reaches a high concentration in a period of 2–3 days.
It can be partially purified by precipitation at pH 4·3. It is partially resistant to the action of trypsin, RNAse and DNAse. It is relatively stable at pH 6–10.
Experimental results suggest that the soluble antigen remains antigenically active after heating at 56° C. and treatment with 0·5% phenol or 0·35% formal-dehyde, but that such heating markedly reduces the ability to stimulate formation of neutralizing antibody.
Rabbits and mice appear to differ in the production of neutralizing antibody following immunization against soluble antigen in which residual live virus was inactivated by heat, phenol or formaldehyde.
It is suggested that this difference may depend on the different susceptibility to traces of incompletely inactivated virus remaining in the immunizing antigens.
The authors are grateful to Miss T. Madsen for her assistance in some aspects of this work. Dr N. Sapeika kindly made available facilities for the in vitro anaphylaxis experiments.
Financial assistance was received from the Nkana-Kitwe and Chingola Poliomyelitis Research Funds.