Nineteen cases from an epidemic of disseminated Kaposi's sarcoma in homosexual men were studied by clinical, virologic, immunologic, and genetic methods. The patients were all male homosexuals ranging in age from 29 to 52 years, with histories of multiple sexually transmitted diseases and exposure to both prescription and recreational drugs. Sites of disease included skin (16 of 19 patients), lymph nodes (13 patients), gastrointestinal tract (12 patients), spleen (three patients), and lung (one patient). Most patients had elevated levels of serum immunoglobins, positive antibody titers to hepatitis A and B virus, cytomegalovirus and Epstein-Barr virus, and impairment of cell-mediated immunologic reactions. The frequency of HLA-DR5 in these patients was significantly elevated. Two of the 19 patients died. Although the precise cause of this epidemic is unknown, it is likely that a genetic predisposition, an acquired immunoregulatory defect, and one or more infectious agents and drugs may be involved.

Virus shedding was detected in 77% of homosexual subjects and in only 6% of heterosexual controls. The overall virus isolation rate in homosexual subjects was not significantly different among HIV-seropositive (79%) and HIV-seronegative (74%) individuals. In about 20% of homosexual subjects, virus shedding from multiple sites was observed. The most frequently isolated virus was cytomegalovirus (CMV) (41%), followed by enteroviruses (23%), herpes simplex virus (HSV) (7%), and adenoviruses (6%). In the control group, about 50% of subjects were seronegative for HSV-1 and 2, and about 70% were negative for CMV and Epstein-Barr virus (EBV). Only 2% of homosexuals were seronegative for CMV, about 5% for HSV-1 and 2, and about 20% for EBV. No differences were found in antibody levels against varicella-zoster virus (VZV) among the control and homosexual groups. The proportion of seronegatives for Coxsackie and hepatitis viruses was significantly higher in control than in homosexual subjects. However, no differences in the proportion of seronegatives for measles, mumps, and rubella were observed. No HIV-antibody-negative individual was detected with an OKT4/OKT8 ratio of less than 0.75. On the other hand, only HIV-positive subjects, with a ratio of less than 0.75, had high serum IFN alpha titers. The results suggest that the high rate of virus shedding among HIV-negative homosexual subjects might be a factor in the development of AIDS in this high-risk population.

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Hairless mice were immunized with herpes simplex virus type 1 (HSV-1) envelope antigen (EAG), EAG in association with polyriboinosinic . polyribocytidylic acid-poly-L-lysine complexed with carboxymethylcellulose (PICLC), and inactivated purified HSV-1 (VAG). After 2 weeks the mice were challenged by a percutaneous HSV-1 infection in the orofacial (OF) or lumbosacral (LS) skin area. Following immunization a consistent cell-mediated immune response was observed in all immunized mice, although the humoral immune response was very low, or not detectable. After challenge, a marked secondary humoral and cell-mediated immune response developed in all immunized mice, and the animals were protected against the development of skin lesions and the fatal outcome of infection. However, the establishment of latent infections in the sensory ganglia was not prevented by the immunization procedure.