Persons with suspected HIV infection are asked to identify their possible source partners. The importance of partner referral is emphasized and assisted recruitment or active tracing is offered if necessary. Source partners will not be approached uninvited. If a partner states that he/she does not want to be contacted, then he/she will not be contacted further for the purpose of this study or for any other study. All patients are offered HIV counseling and plasma testing for HIV-1 RNA and CD4+ cells. Blood specimens are collected for plasma determination, and cellular and plasma fractions are collected for CAF and neutralization antibodies. Neutralization assays are used to detect humoral immune response in patients with primary HIV infection. Genital fluids and saliva are analyzed for viral RNA. Patients are seen in the clinic on Day 1 for blood draw and return 2 weeks later for blood test results. A follow-up period of at least 4 weeks is planned. Compensation is provided to all patients.