HIV SeropositivityHIV SeroprevalenceHIV InfectionsSubstance Abuse, IntravenousHIV AntibodiesHIV Envelope Protein gp120HIV-1Neutralization TestsSexual BehaviorRisk FactorsDisease ProgressionSeroepidemiologic StudiesAntigens, CD4Molecular Sequence DataRNA VirusesVaccinia virusAntibodies, ViralVirus ReplicationReceptors, VirusVirus CultivationVirus SheddingImmunoglobulin GEnzyme-Linked Immunosorbent AssayVirus DiseasesSimian virus 40Virus AssemblyAntibodies, BacterialInfluenza A Virus, H1N1 SubtypePlant VirusesChlamydophila pneumoniaeDNA VirusesDefective VirusesSerologic TestsChlamydophila InfectionsMeasles virusSindbis VirusHIV SeronegativityPrevalenceRNA, ViralHepatitis B virusRabies virusInfluenza A Virus, H5N1 SubtypeAcquired Immunodeficiency SyndromeHepatitis CVirus ActivationHepatitis A virusInfluenza A Virus, H3N2 SubtypeAntigens, ViralTumor Virus InfectionsWest Nile virusRespiratory Syncytial VirusesDNA, ViralHerpesvirus 2, HumanHelicobacter pyloriHelicobacter InfectionsGenes, ViralVirus LatencySimian immunodeficiency virusViral LoadTime FactorsCytomegalovirus InfectionsViral ProteinsVesicular stomatitis Indiana virusPolymerase Chain ReactionAntiviral AgentsCell LineHemagglutinin Glycoproteins, Influenza VirusToxocariasisHepatitis BAntibodies, ProtozoanBlood DonorsJC VirusCytomegalovirusOncogenic VirusesCercopithecus aethiopsCase-Control StudiesVero CellsVirionCD4 Lymphocyte CountHepatitis A Virus, HumanHepacivirusAnti-HIV AgentsHerpes GenitalisCohort StudiesCross-Sectional StudiesMumps virusToxoplasmosisParainfluenza Virus 1, HumanAIDS SerodiagnosisMosaic VirusesProspective StudiesCells, CulturedImmunoglobulin MVirus AttachmentPapillomavirus InfectionsPhylogenySemliki forest virusEpstein-Barr Virus InfectionsToxocaraAvian Sarcoma Viruses