Human CMV establishes a lifelong latent infection in the majority of people worldwide. Although most infections are asymptomatic, immunocompetent hosts devote an extraordinary amount of immune resources to virus control. To increase our understanding of CMV immunobiology in an animal model, we used a genomic approach to comprehensively map the C57BL/6 CD8 T cell response to murine CMV (MCMV). Responses to 27 viral proteins were detectable directly ex vivo, the most diverse CD8 T cell response yet described within an individual animal. Twenty-four peptide epitopes were mapped from 18 Ags, which together account for most of the MCMV-specific response. Most Ags were from genes expressed at early times, after viral genes that interfere with Ag presentation are expressed, consistent with the hypothesis that the CD8 T cell response to MCMV is largely driven by cross-presented Ag. Titration of peptide epitopes in a direct ex vivo intracellular cytokine staining assay revealed a wide range of functional avidities, with no obvious correlation between functional avidity and the strength of the response. The immunodominance hierarchy varied only slightly between mice and between experiments. However, H-2b-expressing mice with different genetic backgrounds responded preferentially to different epitopes, indicating that non-MHC-encoded factors contribute to immunodominance in the CD8 T cell response to MCMV.

The cytotoxic T-lymphocyte (CTL) response against the murine cytomegalovirus (MCMV) immediate-early gene 1 (IE1) 89-kDa phosphoprotein pp89 plays a major role in protecting BALB/c mice against the lethal effects of the viral infection. CTL populations specific to MCMV early-phase and structural antigens are also generated during infection, but the identities of these antigens and their relative contributions to overall immunity against MCMV are not known. We previously demonstrated that DNA vaccination with a pp89-expressing plasmid effectively generated a CTL response and conferred protection against infection (J. C.

Background:Interferons and viral infections stimulate the production of 25-hydroxycholesterol. Results: 25-Hydroxycholesterol significantly alters cholesterol ester and sphingolipid levels and activates the integrated stress response. Conclusion: 25-Hydroxycholesterol activates the GCN2/eIF2␣/ATF4 integrated stress response likely by causing cysteine depletion and/or by generating oxidative stress. Significance: Altering important membrane lipids and activating the integrated stress response may contribute to the antiviral activity of 25-hydroxycholesterol.

We previously showed that intradermal immunization with plasmids expressing the murine cytomegalovirus (MCMV) protein IE1-pp89 or M84 protects against viral challenge and that coimmunization has a synergistic protective effect (C. S. Morello, L. D. Cranmer, and D. H. Spector, J. Virol. 74:3696-3708, 2000). Using an intracellular gamma interferon cytokine staining assay, we have now characterized the CD8 ؉ T-cell response after DNA immunization with pp89, M84, or pp89 plus M84. The pp89-and M84-specific CD8 ؉ T-cell responses peaked rapidly after three immunizations. DNA immunization and MCMV infection generated similar levels of pp89-specific CD8 ؉ T cells. In contrast, a significantly higher level of M84-specific CD8 ؉ T cells was elicited by DNA immunization than by MCMV infection. Fusion of ubiquitin to pp89 enhanced the CD8 ؉ T-cell response only under conditions where vaccination was suboptimal. Three immunizations with either pp89, M84, or pp89 plus M84 DNA also provided significant protection against MCMV infection for at least 6 months, with the best protection produced by coimmunization. A substantial percentage of antigenspecific CD8؉ T cells remained detectable, and they responded rapidly to the MCMV challenge. These results underscore the importance of considering antigens that do not appear to be highly immunogenic during infection as DNA vaccine candidates.The cytomegaloviruses (CMVs) are large, species-specific, double-stranded DNA viruses that can establish persistent and latent infections in their hosts. Although infection in immunocompetent individuals is usually benign, human CMV (HCMV) is responsible for significant morbidity and mortality in immunosuppressed individuals. It is also the major viral cause of birth defects. Each year 0.5 to 2.5% of newborns are congenitally infected with CMV, and 5 to 10% of these infected infants will display neurologic defects such as hearing loss and impaired learning abilities (2).Although extensive biological and immunological studies have been performed with HCMV, progress has been greatly impeded by the species-specific nature of the virus. Consequently, no animal models are available for direct study of the pathogenesis of HCMV and testing of preventive strategies. Murine CMV (MCMV) greatly resembles its human counterpart with respect to acute infection, establishment of latency, and reactivation after immunosuppression. Because HCMV and MCMV also have much in common with respect to the organization and expression of their genomes and host immune response to the viral gene products, this animal model system has been very useful for the development and testing of strategies for prevention and treatment of CMV infection.MCMV encodes several proteins that play significant roles in the control of virus replication through the induction of adaptive immune responses in its host. Some of the gene products have homologs in HCMV, while others are unique to MCMV. Both humoral and cell-mediated immune responses are induced during MCMV infection. Two of the HCMV an...

Human cytomegalovirus (HCMV) is the major viral cause of birth defects and a serious problem in immunocompromised individuals and has been associated with atherosclerosis. Previous studies have shown that the induction of autophagy can inhibit the replication of several different types of DNA and RNA viruses. The goal of the work presented here was to determine whether constitutive activation of autophagy would also block replication of HCMV. Most prior studies have used agents that induce autophagy via inhibition of the mTOR pathway. However, since HCMV infection alters the sensitivity of mTOR kinase-containing complexes to inhibitors, we sought an alternative method of inducing autophagy. We chose to use trehalose, a nontoxic naturally occurring disaccharide that is found in plants, insects, microorganisms, and invertebrates but not in mammals and that induces autophagy by an mTOR-independent mechanism. Given the many different cell targets of HCMV, we proceeded to determine whether trehalose would inhibit HCMV infection in human fibroblasts, aortic artery endothelial cells, and neural cells derived from human embryonic stem cells. We found that in all of these cell types, trehalose induces autophagy and inhibits HCMV gene expression and production of cell-free virus. Treatment of HCMV-infected neural cells with trehalose also inhibited production of cell-associated virus and partially blocked the reduction in neurite growth and cytomegaly. These results suggest that activation of autophagy by the natural sugar trehalose or other safe mTOR-independent agents might provide a novel therapeutic approach for treating HCMV disease. IMPORTANCEHCMV infects multiple cell types in vivo, establishes lifelong persistence in the host, and can cause serious health problems for fetuses and immunocompromised individuals. HCMV, like all other persistent pathogens, has to finely tune its interplay with the host cellular machinery to replicate efficiently and evade detection by the immune system. In this study, we investigated whether modulation of autophagy, a host pathway necessary for the recycling of nutrients and removal of protein aggregates, misfolded proteins, and pathogens, could be used to target HCMV. We found that autophagy could be significantly increased by treatment with the nontoxic, natural disaccharide trehalose. Importantly, trehalose had a profound inhibitory effect on viral gene expression and strongly impaired viral spread. These data constitute a proof-of-concept for the use of natural products targeting host pathways rather than the virus itself, thus reducing the risk of the development of resistance to treatment. H uman cytomegalovirus (HCMV) infects multiple cell types, including endothelial, smooth muscle, epithelial, and fibroblast cells, monocytes/macrophages, bone marrow progenitor cells, and cells of the neural lineage, and establishes lifelong persistence in the host (for a review, see reference 1). Seroprevalence is high in the general population, and in most healthy individuals, the in...