Heterocyclic Compounds, Bridged-RingHIV InfectionsHIV SeropositivityHIV SeroprevalenceHIV SeronegativityHIV-1Anti-HIV AgentsAIDS SerodiagnosisHIV AntigensAcquired Immunodeficiency SyndromeHIV Protease InhibitorsMolecular StructureSexual BehaviorHomosexuality, MaleRisk-TakingCD4 Lymphocyte CountHIV Reverse TranscriptaseAnti-Retroviral AgentsHIV Core Protein p24