An experiment has shown that ranpirnase is a microbicide. It is believed that topical application of a topical pharmaceutical composition consisting essentially of a prophylactically effective concentration of an enzymatically-active ribonuclease (e.g. ranpirnase) and a viscous vehicle that does not unacceptably interfere with the enzymatic activity (e.g. K-Y® Brand Jelly) will prophylactically protect an individual from a sexually-transmitted viral infection, particularly HIV. It is also believed that e.g. ranpirnase can be delivered to tissues of an individual who is to be prophylactically protected against viral infections by transfecting ranpirnase DNA into human microbiota and exposing the individual to the thus-modified human microbiota. It is also believed that ranpirnase can be delivered to a woman who is to be prophylactically protected against a sexually-transmitted viral infection by use of an intravaginal ring that has been impregnated with ranpirnase.
