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2: Activation of human herpesvirus 6 (HHV-6) replication by human cytomegalovirus (HCMV) in human fibroblast culture
Journal of Clinical Virology 37 Suppl. 1 (2006) S97–118 www.elsevier.com/locate/jcv
Abstracts from the 5th International Conference on HHV-6 & 7, 1−3 May 2006, Barcelona, Spain Cell Biology 1 Overview of HHV-6 cell biology U.A. Gompels *. Department Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, University of London, Keppel St, London WC1E 7HT, UK E-mail address: [email protected] Objective: The Roseolo viruses, HHV-6 (variants A and B) and HHV-7, together with HCMV form the human beta herpesviruses. Genomic comparisons are analysed between these viruses, identifying clear patterns of conserved or hypervariable genes which dictate unique aspects of their cell biology. Summary: HHV-6 and HHV-7 share with HCMV conserved or positional homologues of key genes for cellular entry as well as cellular dissemination and host transmission. These include the conserved herpesvirus fusion modulator complex, gH/gL, and a third component specific for beta herpesviruses, gO, which is hyper variable. They also share two families of inflammatory modulators, chemokine receptors, U51 and U12, which affect host cell signalling at early or late times post infection, respectively, with additional effect on virus replication and passage of infected cells to sites of host transmission. Studies on signalling mechanisms show the receptors are extremely sensitive to specific host cell levels of chemokines or G proteins which ultimately change the signalling potential of the infected cell leading to changes in gene expression including the key human chemokine Rantes/CCL5. During U51 expression, prior to replication, Rantes levels are repressed, a novel immune evasion strategy. Exclusive to HHV-6 are replication and immunological modulators, U94/Rep and chemokine U83, both with potential roles during latent infection. In comparisons between HHV-6 strains of variant A and B groups, U83 is one of the few key hypervariable genes and a potential virulence factor. U83A compared to U83B has distinct specificities for human chemokine receptors which appear to reflect potential latent cell reservoirs and correlate with possible neuropathogenic properties. This chemokine is expressed under unique control with an early spliced form inhibiting chemoattraction of immune cells prior to infection. While complete gene expression is late in infection after replication, now mediating specific immune cell chemoattraction for virus dissemination and persistent infection.
2 Activation of human herpesvirus 6 (HHV-6) replication by human cytomegalovirus (HCMV) in human fibroblast culture D. Boutolleau1,2 *, E. Andr´e-Garnier3 , P. Bonnafous1 , H. Agut1 , A. Gautheret-Dejean1,4 . 1 Laboratoire de Virologie, Universit´e Pierre et Marie Curie-Paris 6, EA 2387, Groupe Hospitalier Piti´e-Salpˆetri`ere, Paris, France, 2 Laboratoire de Bact´eriologie-Virologie, Facult´e de M´edecine Paris Sud, CHU de Bicˆetre, Le Kremlin-Bicˆetre, France, 3 Laboratoire de Virologie, CHU de Nantes, et JE 2437 “G´ en´etique des interactions hˆote-micro-organismes”, Universit´e de Nantes, 1590-8658/ $ – see front matter © 2006 Elsevier B.V. All rights reserved.
Nantes, France, 4 Laboratoire de Microbiologie, Facult´e des Sciences Pharmaceutiques et Biologiques, Paris, France E-mail address: [email protected] Background: Among immunosuppressed patients undergoing transplantation, HCMV and HHV-6 are associated with various and potentially severe complications. The relevance of interactions between both beta herpesviruses and the consequences in terms of pathogenicity is increasingly discussed. In particular, numerous studies support the hypothesis that HHV-6 is associated to HCMV infections during the post transplantation period. To date, no study has evidenced such a phenomenon in vitro. Objectives: To study the potential interactions between HCMV and HHV-6 in vitro using human embryonic lung fibroblasts (HELFs), a culture system in current use in virology laboratories, that allows both HCMV and HHV-6 variant A replications. Study Design: HELF coinfections were performed with HHV-6 U1102 strain and three different HCMV strains (AD169, Towne, Toledo). Results: Our results indicated that all HCMV strains favored HHV-6 replication in a dose-dependant manner. On day 6 post-coinfection of HELFs, the number of HHV-6 antigen positive cells was higher, and HHV-6 cellular load was 10- and 100-fold higher according to the initial HCMV inputs, compared to what was observed in HEFLs infected with U1102 alone. Moreover, HCMV accelerated HHV-6 replication since U100 gene late transcript was detected earlier in coinfected HELFs (day 2 versus day 4). HCMV replication was required to favor HHV-6 replication. The use of culture inserts (0.02 mM) evidenced the implication of intracellular viral interactions, and ruled out the role of soluble cellular factors, as cytokines. Conclusion: HCMV is able to activate HHV-6 replication. The molecular mechanisms involved in this phenomenon remain to be elucidated. 3 Astrocytic HHV-6 infection dysregulates glutamate uptake and expression of glutamate transporters E.L. Williams *, J. Fotheringham, N. Akhyani, S. Jacobson. Viral Immunology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Building 10 Room 5B16, Bethesda, MD, 20892, USA E-mail address: [email protected] Background: Both human herpesvirus-6A and 6B have been shown to infect astrocytes, and have been implicated in numerous neurologic diseases. Glutamate is the principal excitatory neurotransmitter in the CNS, and glutamate excitotoxicity has been implicated in acute injury to the CNS and in chronic neurodegenerative disorders. Astrocytes are major regulators of glutamate homeostatis, mediated through the expression of glutamate receptors and transporters on the cell surface and uptake of synaptic glutamate to prevent excitotoxicity. Objective: To study the effect of HHV-6 infection on glutamate uptake and transporter expression. Study Design: We hypothesize that infection with HHV-6 dysregulates glutamate uptake through the altered expression of glutamate transporters and receptors on the surface of astrocytes. We infected primary astrocytes and an astrocytic cell line (U251) with HHV-6A
Abstracts from the 5th International Conference on HHV-6 & 7, 1−3 May 2006, Barcelona, Spain Cell Biology 1 Overview of HHV-6 cell biology U.A. Gompels *. Department Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, University of London, Keppel St, London WC1E 7HT, UK E-mail address: [email protected] Objective: The Roseolo viruses, HHV-6 (variants A and B) and HHV-7, together with HCMV form the human beta herpesviruses. Genomic comparisons are analysed between these viruses, identifying clear patterns of conserved or hypervariable genes which dictate unique aspects of their cell biology. Summary: HHV-6 and HHV-7 share with HCMV conserved or positional homologues of key genes for cellular entry as well as cellular dissemination and host transmission. These include the conserved herpesvirus fusion modulator complex, gH/gL, and a third component specific for beta herpesviruses, gO, which is hyper variable. They also share two families of inflammatory modulators, chemokine receptors, U51 and U12, which affect host cell signalling at early or late times post infection, respectively, with additional effect on virus replication and passage of infected cells to sites of host transmission. Studies on signalling mechanisms show the receptors are extremely sensitive to specific host cell levels of chemokines or G proteins which ultimately change the signalling potential of the infected cell leading to changes in gene expression including the key human chemokine Rantes/CCL5. During U51 expression, prior to replication, Rantes levels are repressed, a novel immune evasion strategy. Exclusive to HHV-6 are replication and immunological modulators, U94/Rep and chemokine U83, both with potential roles during latent infection. In comparisons between HHV-6 strains of variant A and B groups, U83 is one of the few key hypervariable genes and a potential virulence factor. U83A compared to U83B has distinct specificities for human chemokine receptors which appear to reflect potential latent cell reservoirs and correlate with possible neuropathogenic properties. This chemokine is expressed under unique control with an early spliced form inhibiting chemoattraction of immune cells prior to infection. While complete gene expression is late in infection after replication, now mediating specific immune cell chemoattraction for virus dissemination and persistent infection.
2 Activation of human herpesvirus 6 (HHV-6) replication by human cytomegalovirus (HCMV) in human fibroblast culture D. Boutolleau1,2 *, E. Andr´e-Garnier3 , P. Bonnafous1 , H. Agut1 , A. Gautheret-Dejean1,4 . 1 Laboratoire de Virologie, Universit´e Pierre et Marie Curie-Paris 6, EA 2387, Groupe Hospitalier Piti´e-Salpˆetri`ere, Paris, France, 2 Laboratoire de Bact´eriologie-Virologie, Facult´e de M´edecine Paris Sud, CHU de Bicˆetre, Le Kremlin-Bicˆetre, France, 3 Laboratoire de Virologie, CHU de Nantes, et JE 2437 “G´ en´etique des interactions hˆote-micro-organismes”, Universit´e de Nantes, 1590-8658/ $ – see front matter © 2006 Elsevier B.V. All rights reserved.
Nantes, France, 4 Laboratoire de Microbiologie, Facult´e des Sciences Pharmaceutiques et Biologiques, Paris, France E-mail address: [email protected] Background: Among immunosuppressed patients undergoing transplantation, HCMV and HHV-6 are associated with various and potentially severe complications. The relevance of interactions between both beta herpesviruses and the consequences in terms of pathogenicity is increasingly discussed. In particular, numerous studies support the hypothesis that HHV-6 is associated to HCMV infections during the post transplantation period. To date, no study has evidenced such a phenomenon in vitro. Objectives: To study the potential interactions between HCMV and HHV-6 in vitro using human embryonic lung fibroblasts (HELFs), a culture system in current use in virology laboratories, that allows both HCMV and HHV-6 variant A replications. Study Design: HELF coinfections were performed with HHV-6 U1102 strain and three different HCMV strains (AD169, Towne, Toledo). Results: Our results indicated that all HCMV strains favored HHV-6 replication in a dose-dependant manner. On day 6 post-coinfection of HELFs, the number of HHV-6 antigen positive cells was higher, and HHV-6 cellular load was 10- and 100-fold higher according to the initial HCMV inputs, compared to what was observed in HEFLs infected with U1102 alone. Moreover, HCMV accelerated HHV-6 replication since U100 gene late transcript was detected earlier in coinfected HELFs (day 2 versus day 4). HCMV replication was required to favor HHV-6 replication. The use of culture inserts (0.02 mM) evidenced the implication of intracellular viral interactions, and ruled out the role of soluble cellular factors, as cytokines. Conclusion: HCMV is able to activate HHV-6 replication. The molecular mechanisms involved in this phenomenon remain to be elucidated. 3 Astrocytic HHV-6 infection dysregulates glutamate uptake and expression of glutamate transporters E.L. Williams *, J. Fotheringham, N. Akhyani, S. Jacobson. Viral Immunology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Building 10 Room 5B16, Bethesda, MD, 20892, USA E-mail address: [email protected] Background: Both human herpesvirus-6A and 6B have been shown to infect astrocytes, and have been implicated in numerous neurologic diseases. Glutamate is the principal excitatory neurotransmitter in the CNS, and glutamate excitotoxicity has been implicated in acute injury to the CNS and in chronic neurodegenerative disorders. Astrocytes are major regulators of glutamate homeostatis, mediated through the expression of glutamate receptors and transporters on the cell surface and uptake of synaptic glutamate to prevent excitotoxicity. Objective: To study the effect of HHV-6 infection on glutamate uptake and transporter expression. Study Design: We hypothesize that infection with HHV-6 dysregulates glutamate uptake through the altered expression of glutamate transporters and receptors on the surface of astrocytes. We infected primary astrocytes and an astrocytic cell line (U251) with HHV-6A