RESUMO
Viral infections may manifest as acute or chronic arthritis. Joint involvement arises from either direct infection of the joint, through an immunological response directed towards the virus or autoimmunity. Epidemiological clues to the diagnosis include geographic location and exposure to vector-borne, blood-borne or sexually transmitted viruses. Although not always possible, it is important to diagnose the pathogenic virus, usually by serology, nucleic acid tests or rarely, viral culture. In general, viral arthritides are self-limiting and treatment is targeted at symptomatic relief. This article focuses on the causes, clinical features, diagnosis and treatment of viral arthritides.
Assuntos
Anti-Inflamatórios/uso terapêutico , Artrite Infecciosa/tratamento farmacológico , Artrite Infecciosa/virologia , Articulações/efeitos dos fármacos , Articulações/virologia , Animais , Anti-Inflamatórios/administração & dosagem , Artrite Infecciosa/sangue , Artrite Infecciosa/diagnóstico , Artrite Infecciosa/epidemiologia , Culicidae/virologia , Flaviviridae/crescimento & desenvolvimento , Hepadnaviridae/crescimento & desenvolvimento , Humanos , Insetos Vetores/virologia , Articulações/fisiopatologia , Parvoviridae/crescimento & desenvolvimento , Retroviridae/crescimento & desenvolvimento , Testes Sorológicos , Togaviridae/crescimento & desenvolvimentoRESUMO
Virion assembly in hepadnaviruses is a two-step process leading to (1) the packaging of viral pregenomic RNA and reverse transcriptase into nucleocapsids and (2) the assembly of nucleocapsids with envelope components, which results in the formation of mature virus particles. Characteristically, both steps are intimately coupled to viral DNA synthesis. While assembly of nucleocapsids is coupled to the protein priming of reverse transcription, virion formation is linked to genome maturation.
Assuntos
Hepadnaviridae/crescimento & desenvolvimento , Hepadnaviridae/metabolismo , DNA Viral/genética , DNA Viral/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Hepadnaviridae/genética , Nucleocapsídeo/genética , Nucleocapsídeo/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , DNA Polimerase Dirigida por RNA/metabolismo , Transcrição GênicaRESUMO
Foamy viruses make up a distinct subgroup of retroviruses. They are widely distributed among nonhuman primates, felines, and bovines. In their natural hosts and in cases of rare zoonotic transmissions to humans foamy viruses cause persistent and apparently benign infections. While foamy viruses are not of medical importance in causing human or animal diseases, they may become valuable tools for somatic gene transfer in the future. However, a better understanding of the molecular biology of this virus group is a prerequisite for the development of foamy virus vectors. In this respect, recent research has revealed major differences between the foamy virus and the general retroviral replication strategies and some similarities to hepadnaviruses.
Assuntos
Infecções por Retroviridae/virologia , Spumavirus/genética , Animais , Gatos , Bovinos , Genoma , Hepadnaviridae/crescimento & desenvolvimento , Humanos , Biologia Molecular , Primatas , Infecções por Retroviridae/transmissão , Spumavirus/crescimento & desenvolvimento , Spumavirus/fisiologia , Replicação ViralRESUMO
The immunosuppressive agent cyclosporine was given to adult woodchucks during acute experimental infection with woodchuck hepatitis virus (WHV). All 17 woodchucks given WHV alone or with a vehicle resolved the infection (i.e., zero chronicity), but when cyclosporine was given throughout the incubation and acute phases of infection (0-12 or 14 weeks; n = 12), the rate of chronic infection increased to 92%. When cyclosporine was given only during the incubation period (0-4 weeks; n = 10) or only during the acute phase of infection (2-12 weeks; n = 9), the rates increased to 50% and 55%, respectively. However, when the drug was given after the acute phase (8-18 weeks; n = 9), the chronic infection rate (11%) did not differ from that in untreated and vehicle controls. Immune responses inhibited by cyclosporine are important in resolution of acute WHV infection and occur mainly during the first 8 weeks. Immunosuppression of these responses for even short intervals during incubation (e.g., 0-4 weeks) increases the risk of chronicity.
