Update on human herpesvirus 6 biology, clinical features, and therapy.
ABSTRACT Human herpesvirus 6 (HHV-6) is a betaherpesvirus that is closely related to human cytomegalovirus. It was discovered in 1986, and HHV-6 literature has expanded considerably in the past 10 years. We here present an up-to-date and complete overview of the recent developments concerning HHV-6 biological features, clinical associations, and therapeutic approaches. HHV-6 gene expression regulation and gene products have been systematically characterized, and the multiple interactions between HHV-6 and the host immune system have been explored. Moreover, the discovery of the cellular receptor for HHV-6, CD46, has shed a new light on HHV-6 cell tropism. Furthermore, the in vitro interactions between HHV-6 and other viruses, particularly human immunodeficiency virus, and their relevance for the in vivo situation are discussed, as well as the transactivating capacities of several HHV-6 proteins. The insight into the clinical spectrum of HHV-6 is still evolving and, apart from being recognized as a major pathogen in transplant recipients (as exemplified by the rising number of prospective clinical studies), its role in central nervous system disease has become increasingly apparent. Finally, we present an overview of therapeutic options for HHV-6 therapy (including modes of action and resistance mechanisms).
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ABSTRACT: Human herpesvirus 6 (HHV-6) DNA was detected in peripheral blood from exanthem subitum patients during the acute and convalescent phases of infection using the polymerase chain reaction. Although DNA could be detected in non-adherent and adherent mononuclear cells during the acute phase, it was detected predominantly in adherent cells during the convalescent phase; furthermore, viral DNA was found in adherent cells of healthy adults. When adherent mononuclear cells were cultured in vitro, virus was found to replicate well in differentiated cells cultured for 7 days in vitro before infection. When cells were cultured for more than 1 month, no detectable antigen and no evidence of virus growth was observed, but viral DNA could be detected. These apparently latently infected monocytes were treated with phorbol ester, after which virus could be recovered from the cultures. Therefore, we have developed an in vitro latency system for HHV-6; our results suggest that HHV-6 may latently infect monocytes in vivo and in vitro and that it may be reactivated in cells by some factors.Journal of General Virology 07/1991; 72 ( Pt 6):1401-8. · 3.36 Impact Factor
Article: Lack of correlation between human herpesvirus-6 infection and the course of human immunodeficiency virus infection.[show abstract] [hide abstract]
ABSTRACT: Human herpesvirus-6 (HHV-6) and human immunodeficiency virus (HIV) are both tropic for CD4+ lymphocytes. To determine whether HHV-6 infection affects the susceptibility to or the course of HIV infection, HHV-6 titers were measured by an anticomplement immunofluorescence assay in serum of three groups of homosexual or bisexual men: (1) those with AIDS (n = 78), (2) those with HIV-associated lymphadenopathy (LAS; n = 81), and (3) those who were HIV-seronegative (n = 55). Early and late serum samples were available for 45 men with LAS (median interval 49 months). Men with early LAS did not differ from HIV-seronegative men in either the percentage that were HHV-6-seropositive or in the distribution of titers. There was a significantly lower percentage of seropositives in AIDS patients than in the other two groups (P less than .01). LAS patients who progressed to AIDS did not differ in percentage seropositivity or distribution of titers from nonprogressors. HHV-6 titers tended to decrease over time. HHV-6 titers late in LAS were similar to those in AIDS patients. These findings suggest that it is unlikely that previous exposure to HHV-6 either predisposes to or affects the course of HIV infection.The Journal of Infectious Diseases 04/1990; 161(3):567-70. · 6.41 Impact Factor
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ABSTRACT: Complex cells in mammalian visual cortex appear to be non-linear mechanisms lacking a structured receptive field, and different complex cells display mutually inconsistent behaviors. Current models postulate nonlinear interactions among multiple simultaneous afferents, but none explains the diversity of complex cell behaviors. We propose that complex cell inputs are sequential and cyclic. Cells receiving such input behave as if their spatial receptive field changes shape over time. Different putative time-varying receptive fields arise when the number of afferents, their characteristics and/or the sequence of their inputs vary, and simulations show that they exhibit all reported varieties of complex cell behavior. Our results suggest a common functional description for simple and complex cells. Additional non-linearities are unnecessary to explain complex cell behavior.Neuroreport 01/2000; 10(18):3815-9. · 1.66 Impact Factor