The laboratory continues to work on newly identified strains of mycoplasma originated from AIDS patients. One of the isolates: Mycoplasma penetrans, is a new species of mycoplasma isolated from the urogenital tract of patients with AIDS. Genetic analysis of the DNA of this agent by liquid hybridization procedure has shown that this agent is a new species. This organism has properties of adherence, hemadsorption, cytasorption, and invades many different types of mammalian cells. This, it was so named: M penetrans. Specific genetic clones and antibodies against this agent were prepared and used to probe infected tissues. Attempts have been made to develop molecular and serologic assays for the agent and to measure specific immunoresponses. These assays were used to assess the clinical significance and pathogenicity of this agent in humans. The development of species-specific serological tests for mycoplasmas was a unique accomplishment by our group. We continue to explore new tests for other mycoplasmas in addition to the existing ones for Mycoplasma fermentens, M. Penetrans, M genitilium, and M. Pneumonaie. We applied these serological tests to several clinical settings, including patients with HIV infection, non-gonococcal urethritis (UGE), sexually transmitted diseases, and intravenous drug use. We found high prevalences of antibodies to M. Penetrans in patients with Kaposi's sarcoma and antibodies to M. Genitalium in patients with NGU. Using paired donor- recipient specimens, we also found M. Fermentens and M. Genitalium were transmissible through blood transfusion.