Glutamine supplementation suppresses herpes simplex virus reactivation.

Chronic viral infections are difficult to treat, and new approaches are needed, particularly those aimed at reducing reactivation by enhancing immune responses. Herpes simplex virus (HSV) establishes latency and reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and proliferation of activated T cells requires increased metabolism of glutamine. Here, we found that supplementation with oral glutamine reduced virus reactivation in latently HSV-1-infected mice and HSV-2-infected guinea pigs. Transcriptome analysis of trigeminal ganglia from latently HSV-1-infected, glutamine-treated WT mice showed upregulation of several IFN-γ-inducible genes. In contrast to WT mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in latently HSV-1-infected IFN-γ-KO mice. Mice treated with glutamine also had higher numbers of HSV-specific IFN-γ-producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN-γ-associated immune response and reduce the rate of reactivation of latent virus infection.

A herpes simplex virus 2 glycoprotein D mutant generated by bacterial artificial chromosome mutagenesis is severely impaired for infecting neuronal cells and infects only Vero cells expressing exogenous HVEM.

We constructed a herpes simplex virus 2 (HSV-2) bacterial artificial chromosome (BAC) clone, bHSV2-BAC38, which contains full-length HSV-2 inserted into a BAC vector. Unlike previously reported HSV-2 BAC clones, the virus genome inserted into this BAC clone has no known gene disruptions. Virus derived from the BAC clone had a wild-type phenotype for growth in vitro and for acute infection, latency, and reactivation in mice. HVEM, expressed on epithelial cells and lymphocytes, and nectin-1, expressed on neurons and epithelial cells, are the two principal receptors used by HSV to enter cells. We used the HSV-2 BAC clone to construct an HSV-2 glycoprotein D mutant (HSV2-gD27) with point mutations in amino acids 215, 222, and 223, which are critical for the interaction of gD with nectin-1. HSV2-gD27 infected cells expressing HVEM, including a human epithelial cell line. However, the virus lost the ability to infect cells expressing only nectin-1, including neuronal cell lines, and did not infect ganglia in mice. Surprisingly, we found that HSV2-gD27 could not infect Vero cells unless we transduced the cells with a retrovirus expressing HVEM. High-level expression of HVEM in Vero cells also resulted in increased syncytia and enhanced cell-to-cell spread in cells infected with wild-type HSV-2. The inability of the HSV2-gD27 mutant to infect neuronal cells in vitro or sensory ganglia in mice after intramuscular inoculation suggests that this HSV-2 mutant might be an attractive candidate for a live attenuated HSV-2 vaccine.

A varicella-zoster virus mutant impaired for latency in rodents, but not impaired for replication in cell culture.

While trying to generate a site-directed deletion in the ORF63 latency-associated gene of varicella-zoster virus (VZV) Oka, we constructed a virus with an unexpected rearrangement. The virus has a small deletion in both copies of ORF63 and two copies of a cassette inserted between ORFs 64/65 and 68/69 containing (a) truncated ORF62, (b) ORF63 with a small deletion, and (c) full-length ORF64. The virus was not impaired for growth in human cells, induced higher levels of neutralizing antibodies in guinea pigs, and was impaired for latency in cotton rats compared with parental virus (p=0.0022). Additional mutants containing the same truncation in ORF62, with or without the ORF63 deletion, were less impaired for latency. A VZV Oka mutant, replicating to similar titers and inducing a comparable immune response as parental virus, but impaired for latency, might serve as a safer vaccine and be less likely to reactivate to cause zoster.

Protection from herpes simplex virus (HSV)-2 infection with replication-defective HSV-2 or glycoprotein D2 vaccines in HSV-1-seropositive and HSV-1-seronegative guinea pigs.

BACKGROUND: A herpes simplex virus (HSV)-2 candidate vaccine consisting of glycoprotein D (gD2) in alum and monophosphoryl lipid A (MPL) reduced genital herpes disease in HSV-1-seronegative women but not in men or HSV-1-seropositive women. METHODS: To determine the effect of HSV-1 serostatus on effectiveness of different vaccines, we tested gD2 in alum/MPL, gD2 in Freund's adjuvant, and dl5-29 (a replication-defective HSV-2 mutant) in HSV-1-seropositive or HSV-1-seronegative guinea pigs. RESULTS: In HSV-1-seronegative animals, dl5-29 induced the highest titers of neutralizing antibody, and after vaginal challenge with wild-type virus, dl5-29 resulted in lower rates of vaginal shedding, lower levels of HSV DNA in ganglia, and a trend for less acute and recurrent genital herpes, compared with the gD2 vaccines. In HSV-1-seropositive animals, all 3 vaccines induced similar titers of neutralizing antibodies and showed similar levels of protection against acute and recurrent genital herpes after vaginal challenge with wild-type virus, but dl5-29 reduced vaginal shedding after challenge more than did the gD2 vaccines. CONCLUSIONS: dl5-29 Is an effective vaccine in both HSV-1-seropositive and HSV-1-seronegative guinea pigs and was superior to gD2 vaccines in reducing virus shedding after challenge in both groups of animals. dl5-29 Might reduce transmission of HSV-2.

Impairment in reactivation of a latency associated transcript (LAT)-deficient HSV-2 is not solely dependent on the latent viral load or the number of CD8(+) T cells infiltrating the ganglia.

The HSV latency-associated transcript (LAT) is abundantly expressed during virus latency. Previous studies have shown that the latent viral load and CD8(+) T cells in ganglia influence the rate of reactivation of HSV. While LAT is important for efficient reactivation and establishment of latency, it is uncertain how LAT affects either the HSV latent viral load or CD8(+) T cell infiltration of ganglia. We infected mice with LAT-deficient or LAT-restored HSV-2 at a wide range of inocula. We found that the reduced rate of spontaneous ex-vivo reactivation of the LAT-deficient virus was not associated with a higher number of CD8(+) T cells in the ganglia. Reactivation rates were lower for LAT-deficient than LAT restored HSV-2 even when the latent viral loads were similar, indicating that differences in reactivation were not solely dependent on the latent viral load. Therefore, LAT likely has additional functions important for reactivation.

Cell type specific accumulation of the major latency-associated transcript (LAT) of herpes simplex virus type 2 in LAT transgenic mice.

We performed in situ hybridization to determine the cell type specific accumulation of the intron of the latency-associated transcript (LAT) in tissues in HSV-2 LAT transgenic mice in which LAT expression is driven by its native promoter. We identified LAT in multiple cell types in most tissues analyzed from HSV-2 LAT transgenic mice. While weak to moderate signals were seen in brain and spinal cord neurons, epithelial cells, and muscle cells, the strongest signals were detected in neurons from dorsal root and trigeminal ganglia. About 70-86% of neurons in these ganglia were LAT-positive with varying signal intensities, while cells surrounding the neurons were LAT-negative. The frequency of A5 or KH10-positive neurons was similar in LAT-positive and total neurons. These data indicate that HSV-2 LAT promoter activity is not restricted to neurons and that LAT accumulation in ganglionic neurons is likely regulated by cell-specific factors.

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, diminishes lymphoproliferation in the Fas -deficient MRL/lpr(-/-) murine model of autoimmune lymphoproliferative syndrome (ALPS).

OBJECTIVE: Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of apoptosis, often presenting in childhood. Similarly, MRL/lpr(-/-) mice homozygous for Fas mutations develop an ALPS-like disease with autoimmunity, lymphadenopathy, splenomegaly, and expansion of double-negative T cells. Currently, there are no proven therapies with adequate safety margins for sustained abolition of the lymphoproliferation associated with ALPS. We sought to test the ability of valproic acid (VPA), a histone deacetylase inhibitor, to induce apoptosis and inhibit lymphoproliferation. MATERIALS AND METHODS: Human peripheral blood mononuclear cells from patients with ALPS and normal controls were tested in vitro to determine the efficacy of VPA at inducing cell death. VPA was used in vivo to control lymphoproliferation in MRL/lpr(-/-) mice, a model for ALPS. RESULTS: VPA induced cell death in vitro, and was partially inhibited by the pan caspase inhibitor, Z-VAD-FMK. MRL/lpr(-/-) mice treated with VPA for 8 weeks showed significant reductions in spleen and lymph node weights and cellularity compared to controls. A concomitant decrease in double-negative T cells was observed in the spleen, lymph nodes, and peripheral blood. Serum levels of VPA peaked 1 hour after injection, and a 2.5-fold increase in histone acetylation was observed in the spleen at 4 hours after injection. CONCLUSION: Based on our data, VPA is effective at reducing lymphoproliferation in mice, and is currently being studied in a clinical trial as a lympholytic agent in patients with ALPS.

Comparison of immunogenicity and protective efficacy of genital herpes vaccine candidates herpes simplex virus 2 dl5-29 and dl5-29-41L in mice and guinea pigs.

A replication-defective herpes simplex virus (HSV)-2 vaccine, dl5-29, which is deleted for two essential early genes, UL5 and UL29, is highly immunogenic and protective in mice and guinea pigs. In a prior study, a derivative of HSV-2 dl5-29 termed dl5-29-41L, which has an additional deletion in UL41 (that encodes the virion-host shut-off protein), was more immunogenic and protective against challenge with wild-type HSV-2 in mice when compared with dl5-29. To determine if deletion of UL41 improves the efficacy of dl5-29 in protecting guinea pigs from HSV-2, animals were immunized with dl5-29, dl5-29-41L, or PBS. The geometric mean neutralizing antibody titers from the dl5-29 and dl5-29-41L recipients were comparable (10(1.97) and 10(2.19), respectively, p=0.15). After intravaginal challenge with wild-type HSV-2, the dl5-29-41L and dl5-29 recipients shed similar titers of HSV-2 from the vagina. Mean acute disease severity scores, numbers of recurrences during 3 months after infection, and latent viral loads in sacral ganglia were similar for dl5-29 and dl5-29-41L (all p values >0.05). dl5-29 and dl5-29-41L completely protected mice from lethal challenge with HSV-2 and induced virus-specific CD8(+) T cells in the spleens of the animals. Thus, dl5-29 was as immunogenic and protective as dl5-29-41L under these conditions. dl5-29 was at least 250,000-fold less virulent than parental virus by intracranial inoculation in healthy mice, and caused no disease in SCID mice. Both dl5-29-41L and dl5-29 are equally effective and immunogenic in guinea pigs, and dl5-29 is very safe in immunocompromised animals.

Pyrimethamine treatment does not ameliorate lymphoproliferation or autoimmune disease in MRL/lpr-/- mice or in patients with autoimmune lymphoproliferative syndrome.

Autoimmune lymphoproliferative syndrome (ALPS) is an inherited disorder of lymphocyte apoptosis leading to childhood onset of marked lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias, and increased risk of lymphoma. Most cases are associated with heterozygous mutations in the gene encoding Fas protein. Prolonged use of immunosuppressive drugs that do ameliorate its autoimmune complications fail to consistently lessen lymphoproliferation in ALPS. A case series had described children with ALPS, whose spleens (SPL) and lymph nodes decreased in size when treated weekly with pyrimethamine and sulfadoxine; parallel in vitro studies showed only pyrimethamine to promote apoptosis. On the basis of that experience, we undertook additional in vitro lymphocyte apoptosis assays, and measured SPL weights, lymphocyte numbers, and immunophenotypes in Fas-deficient MRL/lpr-/- mice to gain further insights into the utility of combined pyrimethamine/sulfadoxine or pyrimethamine alone. Moreover, seven children with ALPS enrolled in a study of escalating dose of pyrimethamine alone given twice weekly for 12 weeks to determine if their lymphadenopathy and/or splenomegaly would diminish, as assessed by standardized computerized tomography. Neither pyrimethamine alone or with sulfadoxine in the MRL/lpr-/- mice, nor pyrimethamine alone in ALPS patients proved efficacious. We conclude that these drugs do not warrant further use empirically or as part of clinical trials in ALPS Type Ia as a lympholytic agent.

Bortezomib induces apoptosis of Epstein-Barr virus (EBV)-transformed B cells and prolongs survival of mice inoculated with EBV-transformed B cells.

Bortezomib, an inhibitor of the 26S proteasome, is currently approved for treatment of multiple myeloma and is being studied for therapy of non-Hodgkin's lymphoma. We found that Epstein-Barr virus (EBV)-positive B cells with type III latency were more susceptible to killing by bortezomib than those with type I latency. Bortezomib induced apoptosis of EBV lymphoblastoid cell lines (LCLs) by inducing cleavage of caspases 8 and 9; apoptosis was inhibited by pretreatment with a pan-caspase inhibitor. Bortezomib reduced the levels of the p50 and p65 components of the canonical NF-kappaB pathway and reduced the level of p52 in the noncanonical NF-kappaB pathway, which is induced by EBV LMP1. Bortezomib inhibited expression of cIAP-1, cIAP-2, and XIAP, which are regulated by NF-kappaB and function as inhibitors of apoptosis. Bortezomib did not inhibit expression of several other antiapoptotic proteins, including Bcl-2 and Bcl-XL. Finally, bortezomib significantly prolonged the survival of severe combined immunodeficiency mice inoculated with LCLs. These findings suggest that bortezomib may represent a novel strategy for the treatment of certain EBV-associated lymphomas.

Rates of reactivation of latent herpes simplex virus from mouse trigeminal ganglia ex vivo correlate directly with viral load and inversely with number of infiltrating CD8+ T cells.

Herpes simplex viruses (HSV) reactivate at rates proportional to the viral loads in latently infected ganglia. However, these rates vary substantially among infected animals. We assessed whether the numbers of HSV-specific CD8(+) T cells infiltrating latently infected ganglia also affect reactivation rates and contribute to their variability. Following corneal infection of mice with HSV type 2 (HSV-2), we quantified the latent viral loads in dissociated trigeminal ganglia by real-time PCR, the numbers of infiltrating CD8(+) T cells by flow cytometry, and the rates of reactivation by the detection of cell-free virus released from ganglion cells cultured in 96-well plates. The reactivation rates correlated directly with the latent viral loads (P = 0.001) but did so more strongly (P = 10(-7)) when cultures were depleted of CD8(+) T cells. Reactivation rates were reduced in a dose-dependent fashion by adding back ganglion CD8(+) T cells to the cultures (P = 0.003). We related the latent viral loads, numbers of CD8(+) T cells, and reactivation rates by mathematical equations. The rates of reactivation predicted from latent viral loads and numbers of infiltrating CD8(+) T cells in dissociated ganglia correlated with the observed rates of reactivation (P = 0.04). The reactivation of HSV-2 from ganglia ex vivo is determined both by the latent viral load and the number of infiltrating CD8(+) T cells.

Absence or overexpression of the Varicella-Zoster Virus (VZV) ORF29 latency-associated protein impairs late gene expression and reduces VZV latency in a rodent model.

Varicella-zoster virus (VZV) ORF29 encodes the viral single-stranded DNA binding protein and is expressed during latency in human ganglia. We constructed an ORF29 deletion mutant virus and showed that the virus could replicate only in cells expressing ORF29. An ORF29-repaired virus, in which ORF29 was driven by a cytomegalovirus promoter, grew to peak titers similar to those seen with the parental virus. The level of ORF29 protein in cells infected with the repaired virus was greater than that seen with parental virus. Infection of cells with either the ORF29 deletion or repaired virus resulted in similar levels of VZV immediate-early proteins but reduced levels of glycoprotein E compared to those observed with parental virus. Cotton rats infected with the ORF29 deletion mutant had a markedly reduced frequency of latent infection in dorsal root ganglia compared with those infected with parental virus (P < 0.00001). In contrast, infection of animals with the ORF29 deletion mutant resulted in a frequency of ganglionic infection at 3 days similar to that seen with the parental virus. Animals infected with the ORF29-repaired virus, which overexpresses ORF29, also had a reduced frequency of latent infection compared with those infected with parental virus (P = 0.0044). These studies indicate that regulation of ORF29 at appropriate levels is critical for VZV latency in a rodent model.

Schistosoma mansoni infection in eosinophil lineage-ablated mice.

We explore the controversial issue of the role of eosinophils in host defense against helminthic parasites using the established Schistosoma mansoni infection model in 2 novel mouse models of eosinophil lineage ablation (DeltadblGATA and TgPHIL). No eosinophils were detected in bone marrow of infected DeltadblGATA or TgPHIL mice, despite the fact that serum IL-5 levels in these infected mice exceeded those in infected wild type by approximately 4-fold. Liver granulomata from infected DeltadblGATA and TgPHIL mice were likewise depleted of eosinophils compared with those from their respective wild types. No eosinophil-dependent differences in granuloma number, size, or fibrosis were detected at weeks 8 or 12 of infection, and differential accumulation of mast cells was observed among the DeltadblGATA mice only at week 12. Likewise, serum levels of liver transaminases, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) increased in all mice in response to S mansoni infection, with no eosinophil-dependent differences in hepatocellular damage observed. Finally, eosinophil ablation had no effect on worm burden or on egg deposition. Overall, our data indicate that eosinophil ablation has no impact on traditional measures of disease in the S mansoni infection model in mice. However, eosinophils may have unexplored immunomodulatory contributions to this disease process.

Varicella-zoster virus ORF4 latency-associated protein is important for establishment of latency.

Varicella-zoster virus (VZV) encodes at least six genes that are expressed during latency. One of the genes, ORF4, encodes an immediate-early protein that is present in the virion tegument. ORF4 RNA and protein have been detected in latently infected human ganglia. We have constructed a VZV mutant deleted for ORF4 and have shown that the gene is essential for replication in vitro. The ORF4 mutant virus could be propagated when grown in cells infected with baculovirus expressing the ORF4 protein under the human cytomegalovirus immediate-early promoter. In contrast, the VZV ORF4 deletion mutant could not be complemented in cells expressing herpes simplex virus type 1 (HSV-1) ICP27, the homolog of ORF4. Cells infected with baculovirus expressing ORF4 did not complement an HSV-1 ICP27 deletion mutant. VZV-infected cotton rats have been used as a model for latency; viral DNA and latency-associated transcripts are expressed in dorsal root ganglia 1 month or more after experimental infection. Cotton rats inoculated with VZV lacking ORF4 showed reduced frequency of latency compared to animals infected with the parental or ORF4-rescued virus. Thus, in addition to VZV ORF63, which was previously shown to be critical for efficient establishment of latency, ORF4 is also important for latent infection.

Regions of the varicella-zoster virus open reading frame 63 latency-associated protein important for replication in vitro are also critical for efficient establishment of latency.

Varicella-zoster virus (VZV) open reading frame 63 (ORF63) is one of the most abundant transcripts expressed during VZV latency in humans, and ORF63 protein has been detected in human ganglia by several laboratories. Deletion of over 90% of the ORF63 gene showed that the protein is required for efficient establishment of latency in rodents. We have constructed viruses with a series of mutations in ORF63. While prior experiments showed that transfection of cells with a plasmid expressing ORF63 but lacking the putative nuclear localization signal of the protein resulted in increased expression of the protein in the cytoplasm, we found that ORF63 protein remained in the nucleus in cells infected with a VZV ORF63 nuclear localization signal deletion mutant. This mutant was not impaired for growth in cell culture or for latency in rodents. Replacement of five serine or threonine phosphorylation sites in ORF63 with alanines resulted in a virus that was impaired for replication in vitro and for latency. A series of ORF63 carboxy-terminal mutants showed that the last 70 amino acids do not affect replication in vitro or latency in rodents; however, the last 108 amino acids are important for replication and latency. Thus, regions of ORF63 that are important for replication in vitro are also required for efficient establishment of latency.

Comparative efficacy and immunogenicity of replication-defective, recombinant glycoprotein, and DNA vaccines for herpes simplex virus 2 infections in mice and guinea pigs.

Many candidate vaccines are effective in animal models of genital herpes simplex virus type 2 (HSV-2) infection. Among them, clinical trials showed moderate protection from genital disease with recombinant HSV-2 glycoprotein D (gD2) in alum-monophosphoryl lipid A adjuvant only in HSV women seronegative for both HSV-1 and HSV-2, encouraging development of additional vaccine options. Therefore, we undertook direct comparative studies of the prophylactic and therapeutic efficacies and immunogenicities of three different classes of candidate vaccines given in four regimens to two species of animals: recombinant gD2, a plasmid expressing gD2, and dl5-29, a replication-defective strain of HSV-2 with the essential genes UL5 and UL29 deleted. Both dl5-29 and gD2 were highly effective in attenuating acute and recurrent disease and reducing latent viral load, and both were superior to the plasmid vaccine alone or the plasmid vaccine followed by one dose of dl5-29. dl5-29 was also effective in treating established infections. Moreover, latent dl5-29 virus could not be detected by PCR in sacral ganglia from guinea pigs vaccinated intravaginally. Finally, dl5-29 was superior to gD2 in inducing higher neutralizing antibody titers and the more rapid accumulation of HSV-2-specific CD8+ T cells in trigeminal ganglia after challenge with wild-type virus. Given its efficacy, its defectiveness for latency, and its ability to induce rapid, virus-specific CD8(+)-T-cell responses, the dl5-29 vaccine may be a good candidate for early-phase human trials.

The varicella-zoster virus open reading frame 63 latency-associated protein is critical for establishment of latency.

Varicella-zoster virus (VZV) expresses at least six viral transcripts during latency. One of these transcripts, derived from open reading frame 63 (ORF63), is one of the most abundant viral RNAs expressed during latency. The VZV ORF63 protein has been detected in human and experimentally infected rodent ganglia by several laboratories. We have deleted >90% of both copies of the ORF63 gene from the VZV genome. Animals inoculated with the ORF63 mutant virus had lower mean copy numbers of latent VZV genomes in the dorsal root ganglia 5 to 6 weeks after infection than animals inoculated with parental or rescued virus, and the frequency of latently infected animals was significantly lower in animals infected with the ORF63 mutant virus than in animals inoculated with parental or rescued virus. In contrast, the frequency of animals latently infected with viral mutants in other genes that are equally or more impaired for replication in vitro, compared with the ORF63 mutant, is similar to that of animals latently infected with parental VZV. Examination of dorsal root ganglia 3 days after infection showed high levels of VZV DNA in animals infected with either ORF63 mutant or parental virus; however, by days 6 and 10 after infection, the level of viral DNA in animals infected with the ORF63 mutant was significantly lower than that in animals infected with parental virus. Thus, ORF63 is not required for VZV to enter ganglia but is the first VZV gene shown to be critical for establishment of latency. Since the present vaccine can reactivate and cause shingles, a VZV vaccine based on the ORF63 mutant virus might be safer.

Varicella-zoster virus expressing HSV-2 glycoproteins B and D induces protection against HSV-2 challenge.

A recombinant Oka (ROka) varicella-zoster virus (VZV) vaccine was constructed that expresses herpes simplex virus type 2 (HSV-2) glycoproteins B (gB) and D (gD). Guinea pigs received one of four inocula: (a). uninfected cells, (b). recombinant Oka VZV infected cells, (c). recombinant Oka VZV expressing HSV-2 gB/gD (ROka-gB2/gD2) infected cells, or (d) heat-inactivated ROka-gB2/gD2 infected cells. Only animals inoculated with ROka-gB2/gD2 developed high titers of neutralizing antibodies to HSV-2. Animals immunized with ROka-gB2/gD2 had reduced mortality after intravaginal challenge with HSV-2 compared with animals that received ROka or heat-inactivated ROka-gB2/gD2. Animals immunized with ROka-gB2/gD2 had reduced lesions scores for the first 2 weeks after challenge, and reduced shedding of HSV-2 on Days 5 and 7 after challenge, compared to the other two groups. These data show that recombinant VZV expressing HSV-2 antigens must be infectious to offer significant protection against challenge with HSV-2, and that ROka-gB2/gD2 has promise as a candidate HSV-2 vaccine.

Simvastatin induces apoptosis of Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines and delays development of EBV lymphomas.

Simvastatin and pravastatin are inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase, and are used as antihypercholesterolemia drugs. Simvastatin, but not pravastatin, binds to the inserted domain of leukocyte function antigen (LFA)-1 and inhibits the function of LFA-1, including adhesion and costimulation of lymphocytes. Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) express high levels of LFA-1 on their surface and grow in tight clumps. Here we show that simvastatin (2 microM) inhibits clump formation and induces apoptosis of EBV-transformed LCLs. The apoptosis-inducing effect of simvastatin depends on binding to the inserted domain of LFA-1. Simvastatin, but not pravastatin, dissociates EBV latent membrane protein 1 from lipid rafts of LCLs, resulting in down-regulation of nuclear factor kappaB activity and induction of apoptosis. Analysis of multiple EBV-positive and -negative cell lines indicated that both LFA-1 and EBV latent membrane protein 1 expression were required for simvastatin's effects. Administration of simvastatin to severe combined immunodeficiency mice followed by inoculation with LCLs resulted in delayed development of EBV lymphomas and prolonged survival of animals. To our knowledge, this is the first report in which a drug that targets LFA-1 has been used to treat B cell lymphoma. These data suggest that simvastatin may have promise for treatment or prevention of EBV-associated lymphomas that occur in immunocompromised persons.

Varicella-zoster virus ORF47 protein kinase, which is required for replication in human T cells, and ORF66 protein kinase, which is expressed during latency, are dispensable for establishment of latency.

Varicella-zoster virus (VZV) results in a lifelong latent infection in human sensory and cranial nerve ganglia after primary infection. VZV open reading frame 47 (ORF47) and ORF66 encode protein kinases that phosphorylate several viral proteins, including VZV glycoprotein gE and ORF32, ORF62, and ORF63 proteins. Here we show that the ORF47 protein kinase also phosphorylates gI. While ORF47 is essential for virus replication in human T cells and skin, we found the gene to be dispensable for establishment of latent infection in dorsal root ganglia of rodents. ORF66 protein is expressed during latency. Rodents infected with VZV unable to express ORF66 developed latent infection at a rate similar to that for the parental virus. ORF63 transcripts, a hallmark of VZV latency, were also detected in similar numbers of animals infected with the ORF47 and ORF66 mutants and with the parental virus. VZV mutants unable to express four of the six genes that do not have herpes simplex virus (HSV) homologs (ORFs 1, 13, 32, 57) were also unimpaired for establishment of latency. While a truncated HSV VP16 mutant was previously reported to be unable to establish latency in a mouse model, we found that VZV with a deletion of ORF10, the homolog of HSV VP16, was dispensable for establishment of latency. Thus, seven genes, including one expressed during latency, are dispensable for establishing latent VZV infection.