HIV SeropositivityHIV SeroprevalenceHIV InfectionsSubstance Abuse, IntravenousSexual BehaviorRisk FactorsSeroepidemiologic StudiesAntibodies, ViralRNA VirusesVirus ReplicationVaccinia virusVirus DiseasesReceptors, VirusInfluenza A Virus, H1N1 SubtypeVirus CultivationVirus SheddingHepatitis CImmunoglobulin GEnzyme-Linked Immunosorbent AssayRNA, ViralMeasles virusTumor Virus InfectionsOrthomyxoviridae InfectionsAntiviral AgentsSerologic TestsRespiratory Syncytial VirusesHepatitis B virusInfluenza A Virus, H5N1 SubtypePlant VirusesAntigens, ViralSindbis VirusDNA VirusesRespiratory Syncytial Virus InfectionsVirus AssemblySimian virus 40West Nile virusDefective VirusesRabies virusHepatitis BAntibodies, BacterialInfluenza A Virus, H3N2 SubtypePrevalenceEpstein-Barr Virus InfectionsChlamydophila pneumoniaeDNA, ViralHepatitis A virusInfluenza, HumanHIV SeronegativityChlamydophila InfectionsHIV-1Viral ProteinsVirus ActivationHepacivirusAcquired Immunodeficiency SyndromeViral LoadNeutralization TestsCell LineVero CellsSimian immunodeficiency virusVesicular stomatitis Indiana virusHerpesvirus 2, HumanOrthomyxoviridaeCercopithecus aethiopsVirus LatencyDNA Virus InfectionsGenes, ViralHemagglutinin Glycoproteins, Influenza VirusHepatitis B Surface AntigensParainfluenza Virus 1, HumanBlood DonorsMolecular Sequence DataCytomegalovirus InfectionsImmunoglobulin MViral Plaque AssayPolymerase Chain ReactionRNA Virus InfectionsHepatitis C AntibodiesHepatitis AVirionMumps virusHelicobacter pyloriHelicobacter InfectionsHerpesvirus 4, HumanSendai virusCytomegalovirusDengueHerpes GenitalisJC VirusTime FactorsVirus AttachmentToxocariasisGene Expression Regulation, ViralOncogenic VirusesAnti-HIV AgentsSemliki forest virusAntibodies, ProtozoanRespirovirus InfectionsHepatitis A Virus, HumanCytopathogenic Effect, ViralDisease Outbreaks