Acquired cancer resistance to combination immunotherapy from transcriptional loss of class I HLA

Understanding mechanisms of late/acquired cancer immunotherapy resistance is critical to improve outcomes; cellular immunotherapy trials offer a means to probe complex tumor-immune interfaces through defined T cell/antigen interactions. We treated two patients with metastatic Merkel cell carcinoma with autologous Merkel cell polyomavirus specific CD8+ T cells and immune-checkpoint inhibitors. In both cases, dramatic remissions were associated with dense infiltration of activated CD8+s into the regressing tumors. However, late relapses developed at 22 and 18 months, respectively. Here we report single cell RNA sequencing identified dynamic transcriptional suppression of the specific HLA genes presenting the targeted viral epitope in the resistant tumor as a consequence of intense CD8-mediated immunologic pressure; this is distinguished from genetic HLA-loss by its reversibility with drugs. Transcriptional suppression of Class I loci may underlie resistance to other immunotherapies, including checkpoint inhibitors, and have implications for the design of improved immunotherapy treatments.

Prevalence of Human Herpesvirus-8 Salivary Shedding in HIV Increases with CD4 Count

Human herpesvirus-8 (HHV-8) is the etiologic agent of Kaposi’s sarcoma (KS), which occurs in epidemic form in human immunodeficiency virus(HIV)-infected individuals. Saliva is the only mucosal fluid in which infectious HHV-8 has been identified, although factors associated with HHV-8 salivary shedding remain unclear. Our study performed PCR analysis for HHV-8 DNA in saliva (and other body fluids) in 66 HIV- and HHV-8-co-infected women without KS so that we could examine predictors for HHV-8 DNA detection. CD4 count was the most significant predictor of HHV-8 salivary shedding, with increased prevalence of HHV-8 salivary DNA at higher CD4 counts. The odds of salivary HHV8 shedding at CD4 counts > = 350 cells/μL was 63 times the odds of shedding at CD4 < 350 (95%CI, 1.3–3078), with an increase in effect size when the analysis was restricted to those with a CD4 nadir > 200. Analysis of these data suggests an increased potential for HHV-8 transmission early in HIV infection, with implications for HHV-8 prevention.

Development of a low-dose fast-dissolving tablet formulation of Newcastle disease vaccine for low-cost backyard poultry immunisation

The immunisation of backyard poultry is critical for maintaining healthy flocks to provide nutrition and income for low-resource farmers worldwide. A vaccine presentation for flocks of less than 50 birds could make it more affordable and accessible, increasing uptake and impact. Fast-dissolving tablets (FDT) of Newcastle disease virus (NDV) vaccine were produced by freeze drying the LaSota NDV strain combined with excipients into tablets containing a small number of doses and packaged in polymer blister sheets. The NDV-FDT vaccine maintained virus stability for more than six months at 4°C, based on plaque assay and egg infectivity dose data. Stability was further confirmed in a challenge study, where the tablet vaccine elicited a strong immune response and provided 100 per cent protection to vaccinated chickens infected with a virulent strain of NDV. The vaccine tablet can be diluted in water (no needle or syringe required) and administered either in drinking water or with a dropper via an intraocular and/or intransal route. Results indicate that FDTs containing a small number of doses are a feasible presentation for backyard poultry farmers. The compact packaging of the FDTs will also provide cost savings in storing and distributing the vaccine in the cold chain.

Immunology in the Clinic Review Series; focus on host responses: T cell responses to herpes simplex viruses

Herpes virus infections are chronic and co-exist with acquired immune responses that generally prevent severe damage to the host, while allowing periodic shedding of virus and maintenance of its transmission in the community. Herpes simplex viruses type 1 and 2 (HSV-1, HSV-2) are typical in this regard and are representative of the viral subfamily Alphaherpesvirinae, which has a tropism for neuronal and epithelial cells. This review will emphasize recent progress in decoding the physiologically important CD8(+) and CD4(+) T cell responses to HSV in humans. The expanding data set is discussed in the context of the search for an effective HSV vaccine as therapy for existing infections and to prevent new infections.

Herpes simplex virus shedding and plasma human immunodeficiency virus RNA levels in coinfected women

Asymptomatic herpes simplex virus (HSV) shedding was described in a cohort of human immunodeficiency virus (HIV)-infected women, and the association of HSV shedding with changes in plasma HIV RNA load was investigated. Genital, rectal, and oral swabs were obtained daily during a 4-week period for polymerase chain reaction and culture, and concomitant plasma specimens were drawn 3 times weekly for determination of HIV RNA load. During the study, 70% and 79% of subjects shed HSV from the oral cavity and genital area, respectively. Shedding of HSV occurred for a mean of 3.2 days for oral shedding and 5.4 days for genital shedding. Mean plasma HIV RNA loads during periods of HSV shedding and nonshedding and for periods 3 days after the cessation of shedding were compared; no significant differences were found (P=.74). In women who shed HSV, as evaluated by detection of virus, plasma HIV RNA load did not fluctuate with HSV shedding.

Tetramer-guided epitope mapping: rapid identification and characterization of immunodominant CD4+ T cell epitopes from complex antigens

T cell responses to Ags involve recognition of selected peptide epitopes contained within the antigenic protein. In this report, we describe a new approach for direct identification of CD4+ T cell epitopes of complex Ags that uses human class II tetramers to identify reactive cells. With a panel of 60 overlapping peptides covering the entire sequence of the VP16 protein, a major Ag for HSV-2, we generated a panel of class II MHC tetramers loaded with peptide pools that were used to stain peripheral lymphocytes of an HSV-2 infected individual. With this approach, we identified four new DRA1*0101/DRB1*0401- and two DRA1*0101/DRB1*0404-restricted, VP16-specific epitopes. By using tetramers to sort individual cells, we easily obtained a large number of clones specific to these epitopes. Although DRA1*0101/DRB1*0401 and DRA1*0101/DRB1*0404 are structurally very similar, nonoverlapping VP16 epitopes were identified, illustrating high selectivity of individual allele polymorphisms within common MHC variants. This rapid approach to detecting CD4+ T cell epitopes from complex Ags can be applied to any known Ag that gives a T cell response.

Human herpesvirus 8 infection and Kaposi's sarcoma among human immunodeficiency virus-infected and -uninfected women

Little is known about the epidemiology of human herpesvirus 8 (HHV-8) infections among women. A cross-sectional study was conducted of HHV-8 infection among human immunodeficiency virus (HIV)-infected and high-risk HIV-uninfected women. Serological tests with noninduced (latent) and induced (lytic) HHV-8 antigens were used to detect infection among 2483 participants of a multisite cohort. Reactivity to latent antigen was present in 4.1% and to induced antigens in 12.0% of women. Seven of 8 women who reported Kaposi's sarcoma had HHV-8 antibodies. Among HIV-positive women, HHV-8 infection was associated with use of crack, cocaine, or heroin (76% vs. 65%; P<.001), past syphilis (29% vs. 20%; P<.001), an injection drug-using male sex partner (61% vs. 53%; P=.014), black race (P=.010), and enrollment site (P=.015). In multivariate analysis, HIV infection, older age, past syphilis, black race, and enrollment site were independently associated with HHV-8 infection. In this cohort of North American women, HHV-8 infection was associated with HIV infection, drug use, and risky sexual behavior.

CD8 CTL from genital herpes simplex lesions: recognition of viral tegument and immediate early proteins and lysis of infected cutaneous cells

HSV-2 causes chronic infections. CD8 CTL may play several protective roles, and stimulation of a CD8 response is a rational element of vaccine design for this pathogen. The viral Ags recognized by CD8 T cells are largely unknown. It has been hypothesized that HSV inhibition of TAP may favor recognition of virion input proteins or viral immediate early proteins. We tested this prediction using HSV-specific CD8 CTL clones obtained from genital HSV-2 lesions. Drug and replication block experiments were consistent with specificity for the above-named classes of viral proteins. Fine specificity was determined by expression cloning using molecular libraries of viral DNA, and peptide epitopes recognized at nanomolar concentrations were identified. Three of four clones recognized the viral tegument proteins encoded by genes UL47 and UL49. These proteins are transferred into the cytoplasm on virus entry. Processing of the tegument Ag-derived epitopes was TAP dependent. The tegument-specific CTL were able to lyse HLA class I-appropriate fibroblasts after short times of infection. Lysis of keratinocytes required longer infection and pretreatment with IFN-gamma. Another clone recognized an immediate early protein, ICP0. Lymphocytes specific for these lesion-defined epitopes could be reactivated from the PBMC of additional subjects. These data are consistent with an influence of HSV immune evasion genes upon the selection of proteins recognized by CD8 CTL in lesions. Tegument proteins, identified for the first time as Ags recognized by HSV-specific CD8 CTL, are rational candidate vaccine compounds.

Role for HLA class II molecules in HIV-1 suppression and cellular immunity following antiretroviral treatment

HIV-1-infected patients treated early with combination antiretrovirals respond favorably, but not all maintain viral suppression and improved HIV-specific Th function. To understand if genetic factors contribute to this variation, we prospectively evaluated over 18 months 21 early-treated patients stratified by alleles of class II haplotypes. All seven subjects with the DRB1*13-DQB1*06 haplotype, but only 21% of other subjects, maintained virus suppression at every posttreatment measurement. Following HIV-1 p24 antigen stimulation, PBMCs from patients with this haplotype demonstrated higher mean lymphoproliferation and IFN-gamma secretion than did cells from patients with other haplotypes. Two DRB1*13-restricted Gag epitope regions were identified, a promiscuous one that bound its putative restriction element with nanomolar affinity, and another that mapped to a highly conserved region. These findings suggest that class II molecules, particularly the DRB1*13 haplotype, have an important impact on virologic and immunologic responses. The advantage of the haplotype may relate to selection of key HIV-1 Th1 epitopes in highly conserved regions with avid binding to class II molecules. Eliciting responses to the promiscuous epitope region may be beneficial in vaccine strategies.

Tegument-specific, virus-reactive CD4 T cells localize to the cornea in herpes simplex virus interstitial keratitis in humans

Herpes stromal keratitis (HSK) is a prevalent and frequently vision-threatening disease associated with herpes simplex virus type 1 (HSV-1) infection. In mice, HSK progression occurs after viral clearance and requires T cells and neutrophils. One model implicates Th1-like CD4 T cells with cross-reactivity between the HSV-1 protein UL6 and a corneal autoantigen. HSK can be prevented by establishing specific immunological tolerance. However, HSK can also occur in T-cell receptor-transgenic X SCID mice lacking HSV-specific T cells. To study the pathogenesis of HSK in the natural host species, we measured local HSV-specific T-cell responses in HSK corneas removed at transplant surgery (n = 5) or control corneas (n = 2). HSV-1 DNA was detected by PCR in two specimens. HSV-specific CD4 T cells were enriched in three of the five HSK specimens and were not detectable in the control specimens. Reactivity with peptide epitopes within the tegument proteins UL21 and UL49 was documented. Responses to HSV-1 UL6 were not detected. Diverse HLA DR and DP alleles restricted these local responses. Most clones secreted gamma interferon, but not interleukin-5, in response to antigen. HSV-specific CD8 cells were also recovered. Some clones had cytotoxic-T-lymphocyte activity. The diverse specificities and HLA-restricting alleles of local virus-specific T cells in HSK are consistent with their contribution to HSK by a proinflammatory effect.

CD4 T-cell responses to herpes simplex virus type 2 major capsid protein VP5: comparison with responses to tegument and envelope glycoproteins

We used CD4 lymphocyte clones from herpes simplex virus type 2 (HSV-2) lesions or the cervix and molecular libraries of HSV-2 DNA to define HSV-2 major capsid protein VP5 and glycoprotein E (gE) as T-cell antigens. Responses to eight HSV-2 glycoprotein, tegument, nonstructural, or capsid antigens were compared in 19 donors. Recognition of VP5 and tegument VP22 were similar to that of gB2 and gD2, currently under study as vaccines. These prevalence data suggest that HSV capsid and tegument proteins may also be candidate vaccine antigens.

Mucosal shedding of human herpesvirus 8 in men

BACKGROUND

Epidemiologic studies suggest that human herpesvirus 8 (HHV-8) is sexually transmitted among men who have sex with men; however, the mode of transmission is unclear.

METHODS

To evaluate the patterns of shedding of HHV-8, we obtained mucosal-secretion samples from a cohort of HHV-8-seropositive men who had sex with men and had no clinical evidence of Kaposi's sarcoma. Quantitative polymerase-chain-reaction (PCR) assays, in situ PCR assays, and in situ RNA hybridization were used to identify potential sources of infectious HHV-8.

RESULTS

We detected HHV-8 in at least one mucosal sample from 30 of 50 men who were seropositive for HHV-8 (60 percent). Overall, HHV-8 was detected in 30 percent of oropharyngeal samples, as compared with 1 percent of anal and genital samples (P<0.001). In 39 percent of the HHV-8-seropositive men, HHV-8 was detected in saliva on more than 35 percent of the consecutive days on which samples were obtained. The median log titer of HHV-8 from the oral cavity was approximately 2.5 times as high as the titer at all other sites. In situ hybridization studies indicated that HHV-8 DNA and messenger RNA were present in oral epithelial cells. Among 92 men who had sex with men and who were seronegative for the human immunodeficiency virus (HIV), a history of sex with a partner who had Kaposi's sarcoma, deep kissing with an HIV-positive partner, and the use of amyl nitrite capsules ("poppers") or inhaled nitrites were independent risk factors for infection with HHV-8.

CONCLUSIONS

Oral exposure to infectious saliva is a potential risk factor for the acquisition of HHV-8 among men who have sex with men. Hence, currently recommended safer sex practices may not protect against HHV-8 infection.

Antigen-specific T cells localize to the uterine cervix in women with genital herpes simplex virus type 2 infection

Genital reinfection with herpes simplex virus type 2 (HSV-2) is uncommon in humans. The mechanism of acquired immunity is unknown. Because the cervix is a site of HSV exposure, we measured antigen-specific T cell responses to HSV in cervical lymphocytes during both lesional and nonlesional time periods. Cells were expanded without secondary in vitro stimulation with antigen. Proliferative and cytotoxic responses to HSV were detectable in specimens from most subjects. Limiting dilution assays showed a high frequency of antigen-specific cells. Cytotoxic T cell responses included both CD4 and CD8 components. Responses were present both during and between symptomatic infection episodes and persisted during suppressive antiviral therapy. Natural infection with HSV-2 is associated with a persistent cervical mucosal cellular immune response. This local response may possibly assist in limiting the clinical consequences of secondary HSV-2 infection, whether due to endogenous reactivation or exogenous reinfection.

Emergence of ganciclovir-resistant cytomegalovirus disease among recipients of solid-organ transplants

BACKGROUND

Concerns have been raised about emergence of ganciclovir resistance as a result of the advent of both routine oral ganciclovir prophylaxis and highly potent immunosuppression. We retrospectively assessed the occurrence of ganciclovir-resistant cytomegalovirus disease among transplant recipients who had received oral ganciclovir prophylaxis and highly potent immunosuppression.

METHODS

We studied 240 recipients of liver, kidney, or pancreas transplants. Antiviral susceptibility testing of blood cytomegaloviral isolates was done when patients failed to respond to intravenous ganciclovir treatment for symptomatic cytomegalovirus infection. Portions of the UL97 gene associated with ganciclovir resistance were sequenced in cytomegalovirus isolates with phenotypic resistance to ganciclovir.

FINDINGS

Ganciclovir-resistant cytomegalovirus disease developed in five (7%) of 67 seronegative recipients of cytomegalovirus-seropositive organs (D+/R-) compared with none of 173 seropositive recipients (p=0.002). Among the 25 (10.4%) patients who developed cytomegalovirus disease within 1 year after transplantation, five had ganciclovir-resistant cytomegalovirus disease. Among D+/R-transplant recipients, ganciclovir-resistant cytomegalovirus disease was more common among the group receiving the most potent immunosuppression--ie, recipients of kidney and pancreas or pancreas alone (four of 19) compared with all other transplant recipients (one of 48, p=0.02). Ganciclovir-resistant cytomegalovirus disease was diagnosed at a median of 10 months after transplantation (range 7-12) after lengthened exposure to ganciclovir, was associated with previously described mutations of the UL97 gene, and led to serious clinical complications.

INTERPRETATION

Ganciclovir-resistant cytomegalovirus is an important cause of late morbidity among D+/R- transplant recipients who have had lengthened exposure to ganciclovir and have received highly potent immunosuppression. Strategies to reduce this complication, especially among D+/R- patients, are warranted.

Long term persistence of herpes simplex virus-specific CD8+ CTL in persons with frequently recurring genital herpes

Herpes simplex virus (HSV) establishes a lifelong infection in humans. Reactivation of latent virus occurs intermittently so that the immune system is frequently exposed to viral Ag, providing an opportunity to evaluate memory T cells to a persistent human pathogen. We studied the persistence of genital herpes lesion-derived HSV-specific CD8+ CTL from three immunocompetent individuals with frequently recurring genital HSV-2 infection. All CTL clones were HSV-2 type specific and only one to three unique clonotypes were identified from any single biopsy specimen. The TCRBV genes utilized by these clonotypes were sequenced, and clonotype-specific probes were used to longitudinally track these clonotypes in PBMC and genital lesions. CTL clonotypes were consistently detected in PBMC and lesions for at least 2 and up to 7 years, and identical clonotypes infiltrated herpes lesions spaced as long as 7.5 years apart. Moreover, these clones were functionally lytic in vivo over these time periods. Additionally, CTL clones killed target cells infected with autologous viral isolates obtained 6.5 years after CTL clones were established, suggesting that selective pressure by these CTL did not result in the mutation of CTL epitopes. Thus, HSV recurs in the face of persistent CD8+ CTL with no evidence of clonal exhaustion or mutation of CTL epitopes as mechanisms of viral persistence.

HLA-DQ tetramers identify epitope-specific T cells in peripheral blood of herpes simplex virus type 2-infected individuals: direct detection of immunodominant antigen-responsive cells

Ag-specific CD4+ T cells are present in peripheral blood in low frequency, where they undergo recruitment and expansion during immune responses and in the pathogenesis of numerous autoimmune diseases. MHC tetramers, which constitute a labeled MHC-peptide ligand suitable for binding to the Ag-specific receptor on T cells, provide a novel approach for the detection and characterization of such rare cells. In this study, we utilized this technology to identify HLA DQ-restricted Ag-specific T cells in the peripheral blood of human subjects and to identify immunodominant epitopes associated with viral infection. Peptides representing potential epitope regions of the VP16 protein from HSV-2 were loaded onto recombinant DQ0602 molecules to generate a panel of Ag-specific DQ0602 tetramers. VP16 Ag-specific DQ-restricted T cells were identified and expanded from the peripheral blood of HSV-2-infected individuals, representing two predominant epitope specificities. Although the VP16 369-380 peptide has a lower binding affinity for DQ0602 molecules than the VP16 33-52 peptide, T cells that recognized the VP16 369-380 peptide occurred at a much higher frequency than those that were specific for the VP16 33-52 peptide.

Herpes simplex virus: the importance of asymptomatic shedding

Herpes simplex virus (HSV) is frequently shed after infection of the genital or perianal area. HSV shedding, as determined by culture, occurs on about 3% of days for immunocompetent women and men, and more for persons with HIV infection or if measured by polymerase chain reaction (PCR). Most horizontal and vertical transmission of HSV occurs during unrecognized or asymptomatic shedding, and the majority of HSV-2-infected persons are unaware of their infection. Many persons with 'asymptomatic' HSV-2 infection can learn to recognize genital signs and symptoms as recurrences of HSV-2 infection. However, some shedding episodes remain truly asymptomatic even after patient education. Antiviral therapy dramatically reduces asymptomatic shedding, and trials to evaluate its effect on HSV transmission are underway.

MHC-peptide ligand interactions establish a functional threshold for antigen-specific T cell recognition

Antigen-specific T cell recognition is dependent on the functional density of the TCR-ligand, which consists of specific MHC molecules and a specifically bound peptide. We have examined the influence of the affinity and concentration of exogenous peptide and the density of specific MHC molecules on the proliferation of a CD4+, DQA1*0501/DQB1*0201 (DQ2.1)-restricted, HSV-2-specific T cell clone. Using antigen peptide analogs with different mutations of known DQ2-anchor residues, T cell response was reduced in an peptide-affinity and - concentration specific manner. The decrease using weaker binding peptides was gradual as stimulation with a peptide with intermediate affinity yielded intermediate T cell proliferation and the poorest binding peptide induced an even weaker T cell response. MHC class II density on the APC was modified using DQ2 homo- and heterozygous B-LCLs as APCs, however this variation of MHC concentration had no effect on T cell proliferation. We interpret this as a reflection of a low threshold for activation of the T cell clone, in which peptide-MHC avidity is the over-riding determinant of the strength of ligand signal.

Peptide binding affinity and pH variation establish functional thresholds for activation of HLA-DQ-restricted T cell recognition

Peptides derived from the HSV-2 VP16 protein were utilized for studies of peptide binding to DQ0302 molecules and T cell activation at both neutral and acidic pH. The native peptide VP16 430-444 contains an Asp at position 442, binds to DQ0302 strongly, with a Kd value of 50nM at acidic pH and very weakly, with a Kd value of greater than 10 microM at neutral pH. A truncated version of 430-444, i.e., VP16 433-442, binds with an affinity 10-fold lower compared to 430-444 at acidic pH, and binding at neutral pH was barely detectable. The homologous peptide 430-444,442A has an Asp to Ala substitution at position 442 and binds to DQ0302 with a Kd similar to 433-442. The short truncated analog 433-442A binds very poorly at both acidic and neutral pH. Both the wild type 430-444 and 433-442 peptides stimulated a HSV-specific T cell clone after a brief incubation with antigen presenting cells (APC) expressing DQ0302 at acidic pH. Much higher concentrations of wild type peptides were needed to activate T cells at neutral pH. In contrast, APC pulsed with Ala-substituted peptides 430-444,442A or 433-442A at neutral pH failed to stimulate the T cell clone, while APC pulsed at acidic pH and subsequently washed led to successful T cell activation. The Ala-substituted peptide was recognized by the T cell clone at neutral pH only when it was present in the APC culture throughout the stimulation process. While the MHC-peptide complexes formed with the native peptide are stable, complexes formed with the Ala-substituted peptide had a functional t1/2 of less than 4 hr at neutral pH.

An important role for major histocompatibility complex class I-restricted T cells, and a limited role for gamma interferon, in protection of mice against lethal herpes simplex virus infection

Herpes simplex virus (HSV) inhibits major histocompatibility complex (MHC) class I expression in infected cells and does so much more efficiently in human cells than in murine cells. Given this difference, if MHC class I-restricted T cells do not play an important role in protection of mice from HSV, an important role for these cells in humans would be unlikely. However, the contribution of MHC class I-restricted T cells to the control of HSV infection in mice remains unclear. Further, the mechanisms by which these cells may act to control infection, particularly in the nervous system, are not well understood, though a role for gamma interferon (IFN-gamma) has been proposed. To address the roles of MHC class I and of IFN-gamma, C57BL/6 mice deficient in MHC class I expression (beta2 microglobulin knockout [beta2KO] mice), in IFN-gamma expression (IFN-gammaKO mice), or in both (IFN-gammaKO/beta2KO mice) were infected with HSV by footpad inoculation. beta2KO mice were markedly compromised in their ability to control infection, as indicated by increased lethality and higher concentrations of virus in the feet and spinal ganglia. In contrast, IFN-gamma appeared to play at most a limited role in viral clearance. The results suggest that MHC class I-restricted T cells play an important role in protection of mice against neuroinvasive HSV infection and do so largely by mechanisms other than the production of IFN-gamma.

Structural basis of specificity and degeneracy of T cell recognition: pluriallelic restriction of T cell responses to a peptide antigen involves both specific and promiscuous interactions between the T cell receptor, peptide, and HLA-DR

TCR engagement of peptide-MHC class II ligands involves specific contacts between the TCR and residues on both the MHC and peptide molecules. We have used molecular modeling and assays of peptide binding and T cell function to characterize these interactions for a CD4+ Th1 cell clone, ESL4.34, which recognizes a peptide epitope of the herpes simplex type 2 virus virion protein, VP16 393-405, in the context of several HLA-DR alleles. This clone responded to VP16 393-405 in proliferation and cytotoxicity assays when presented by DRB1*0402, DRB1*1102, and DRB1*1301, which share a common amino acid sequence, ILEDE, at residues 67-71 in the alpha-helical portion of the DRbeta polypeptide, but not when presented by other DR4, DR11, and DR13 alleles that are negative for this sequence. Using a panel of APCs expressing DR4 molecules that were mutagenized in vitro at individual residues within this shared epitope and using peptide analogues with single amino acid substitutions of predicted MHC and TCR contact residues, a unit of recognition was identified dependent on DRbeta residues 67-71 and relative position 4 (P4) of the VP16 393-405 peptide. The interactions of this portion of the peptide-DR ligand with the ESL4.34 TCR support a structural model for MHC-biased recognition in some Ag-specific and alloreactive T cell responses and suggest a possible mechanism for autoreactive T cell selection in rheumatoid arthritis.

Recognition of herpes simplex virus type 2 tegument proteins by CD4 T cells infiltrating human genital herpes lesions

The local cellular immune response to herpes simplex virus (HSV) is important in the control of recurrent HSV infection. The antiviral functions of infiltrating CD4-bearing T cells may include cytotoxicity, inhibition of viral growth, lymphokine secretion, and support of humoral and CD8 responses. The antigens recognized by many HSV-specific CD4 T cells localizing to genital HSV-2 lesions are unknown. T cells recognizing antigens encoded within map units 0. 67 to 0.73 of HSV DNA are frequently recovered from herpetic lesions. Expression cloning with this region of DNA now shows that tegument protein VP22 and the viral dUTPase, encoded by genes UL49 and UL50, respectively, are T-cell antigens. Separate epitopes in VP22 were defined for T-cell clones from each of three patients. Reactivity with the tegument protein encoded by UL21 was identified for an additional patient. Three new epitopes were identified in VP16, a tegument protein associated with VP22. Some tegument-specific CD4 T-cell clones exhibited cytotoxic activity against HSV-infected cells. These results suggest that herpes simplex tegument proteins are processed for antigen presentation in vivo and are possible candidate compounds for herpes simplex vaccines.

Human herpesvirus 8 in the prostate glands of men with Kaposi's sarcoma

The epidemiology of human immunodeficiency virus (HIV)-associated Kaposi's sarcoma (KS) resembles that of a sexually transmitted pathogen. However, human herpesvirus 8 (HHV-8), the proposed cause of KS, is found in semen only infrequently and at low titers. To determine whether HHV-8 was present in the urogenital tract, transrectal ultrasound-guided prostate biopsies were obtained from six men with KS (five with concurrent HIV infection) and four without KS (three with concurrent HIV) and assayed for HHV-8 by PCR. Nine of the 10 men were seropositive for HHV-8. Five of nine HHV-8-seropositive men had HHV-8 DNA detected in prostate tissue by solution-based PCR. All five currently had KS or had it previously. In two subjects, prostate tissue was the only identified source of HHV-8. In situ PCR on serial sections of prostate indicated that HHV-8 infection was localized to discrete areas of the prostate. When detected, HHV-8 DNA was present in the nuclei of >90% of the glandular epithelial cells. In situ hybridization for HHV-8 mRNA revealed that between 1 and 5% of cells harboring HHV-8 DNA expressed viral transcripts associated with HHV-8 replication (T1.1 transcript), while >90% expressed gene products associated with viral latency (T0.7 transcript). Intermittent replication of HHV-8 in the prostate and subsequent shedding of virus in semen may be crucial factors for determining whether HHV-8 can be transmitted through sexual activity.

Clearance of HSV-2 from recurrent genital lesions correlates with infiltration of HSV-specific cytotoxic T lymphocytes

The mechanisms involved in host clearance of symptomatic mucocutaneous herpes simplex virus (HSV) infection are unclear. We studied the functional properties of bulk cultures of skin-infiltrating lymphocytes from normal skin and serial biopsies of recurrent genital HSV-2 lesions, and compared HSV-specific and NK responses with viral clearance. HSV-specific CD4+ or CD8+ T cells were rarely detected in lymphocytes cultured from normal skin. The total lymphocyte count and HSV-specific and NK-like effector cell activities were markedly higher in cultures derived from lesional skin. HSV-specific CD4+ proliferative responses and NK-like cytotoxic responses were present at all stages of herpetic lesions, including biopsies early in the disease course. In contrast, cytotoxic T lymphocyte activity was generally low among cells derived from early culture-positive lesions, and increased during lesion evolution. Viral clearance from the lesion site was associated with a high level of local cytolytic activity towards HSV-infected cells. The phenotypes of cells with HSV-specific cytotoxic responses varied between patients, having CD4+ and CD8+ components. Immunotherapeutic approaches to HSV should be directed at improving in vivo cytolytic activity to HSV.

Reactivities of human sera with human herpesvirus-8-infected BCBL-1 cells and identification of HHV-8-specific proteins and glycoproteins and the encoding cDNAs

The reactivates of human sera with uninduced and phorbol ester (TPA)-induced human herpesvirus-8 (HHV-8)-infected BCBL-1 cells were examined by immunofluorescence assay (IFA) and by radioimmunoprecipitation reactions (RIP). The seroprevalence of HHV-8 infections is low in the United States general population and only low levels of HHV-8 antibodies were detected in the seropositive sera. In contrast, high levels of antibodies against HHV-8 lytic and latent antigens were detected by IFA in the sera from HIV+ Kaposi's sarcoma (KS)-positive individuals. These sera recognized several proteins and glycoproteins from BCBL-1 cells in RIP reactions. Two types of antibody responses were detected in the sera from HIV+ KS- homosexual men. In majority of the sera with and without detectable HHV-8 DNA in the peripheral blood mononuclear cells (PBMC), significantly low levels of HHV-8 antibodies were detected by IFA. These sera recognized only a subset of HHV-8 proteins and glycoproteins in RIP reactions. In contrast, in a subgroup of sera from HIV+ KS- homosexual men, higher levels of IFA antibodies against HHV-8 lytic and latent antigens were detected. These sera also recognized several viral proteins and glycoproteins in RIP reactions. These results suggest that antibody response profiles to HHV-8 infection vary significantly and serologic assays to detect antibody responses to a panel of both lytic and latent antibodies may be required for maximum sensitivity. Screening of a cDNA library from TPA-induced BCBL-1 cells with an HIV+ KS+ serum identified cDNAs encoding 12 HHV-8 proteins. Further characterization of these HHV-8 proteins would define the HHV-8 antigens useful for seroepidemiological studies and in discriminating lytic, latent, past, and/or reactivation infections.

Chronic vulvar ulceration in an immunocompetent woman due to acyclovir-resistant, thymidine kinase-deficient herpes simplex virus

A 34-year-old healthy woman presented with a 15-month history of persistent, nonhealing vulvar ulcerations due to herpes simplex virus (HSV) type 2. Extensive dermatologic workup and serial skin biopsies failed to reveal an underlying vulvar dermatosis or autoimmune bullous disorder. Virologic studies revealed resistance to acyclovir in vitro due to deficiency in thymidine kinase activity. Serum antibody to human immunodeficiency virus was negative on two occasions, separated by 1 year. Immunologic evaluation showed normal HSV-specific proliferative and CD8 cytotoxic T lymphocyte responses as well as normal NK cell function. Vulvar lesions failed to heal in association with trials of topical trifluorothymidine and oral valacyclovir but resolved completely with the application of 1% foscarnet cream. No recurrence of HSV has been observed in 24 months of follow-up to date.

Famciclovir for the suppression of symptomatic and asymptomatic herpes simplex virus reactivation in HIV-infected persons. A double-blind, placebo-controlled trial

BACKGROUND

Herpes simplex virus (HSV) infection is one of the most common opportunistic infections in HIV-infected persons. However, most documentation of the effectiveness of antiviral therapy in reducing HSV reactivation is anecdotal.

OBJECTIVE

To evaluate the quantitative effect of antiviral therapy on the frequency of HSV reactivation in HIV-infected persons.

DESIGN

Double-blind, placebo-controlled, crossover trial.

SETTING

Research clinic at a university hospital.

PATIENTS

48 persons (45 men and 3 women) who were HIV positive and HSV seropositive.

INTERVENTION

Patients were randomly assigned to receive famciclovir, 500 mg orally twice daily, or placebo for 8 weeks. They then crossed over to receive the other regimen after a 1-week washout period.

MEASUREMENTS

Patients obtained daily cultures of their perirectal, urethral, oral, and genital areas and kept dairy records of signs and symptoms of genital and oral-labial herpes.

RESULTS

The median CD4 cell count at study entry was 384 cells/mm3. In the intention-to-treat analysis of the first study period, HSV was isolated on 122 of 1114 (11%) placebo days compared with 9 of 1071 (1%) famciclovir days (relative risk, 0.15; P < 0.001). For patients who completed the crossover, the median difference in days with symptoms between placebo and famciclovir was 13.8% of days and the median difference in days on which HSV was isolated was 5.4% of days (P < 0.001 for both). Percentage of days with HSV-2 shedding was reduced from 9.7% to 1.3%. Breakthrough reactivations that occurred while patients were receiving famciclovir were infrequent, short, and often asymptomatic, HSV-2 isolates from these reactivations were susceptible to penciclovir in vitro.

CONCLUSIONS

Antiviral chemotherapy with famciclovir results in clinically and statistically significant reductions in the symptoms associated with HSV infection and the symptomatic and asymptomatic shedding of HSV among HIV-positive persons.

Herpes simplex virus type 1 renders infected cells resistant to cytotoxic T-lymphocyte-induced apoptosis

Many viruses interfere with apoptosis of infected cells, presumably preventing cellular apoptosis as a direct response to viral infection. Since cytotoxic T lymphocytes (CTL) induce apoptosis of infected cells as part of the "lethal hit," inhibition of apoptosis could represent an effective immune evasion strategy. We report here herpes simplex virus type 1 (HSV-1) interference with CTL-induced apoptosis of infected cells and show that HSV-1 inhibits the nuclear manifestations of apoptosis but not the membrane changes. The HL-60 cell line (human promyelocytic leukemia) undergoes apoptosis in response to many stimuli, including incubation with ethanol. After HSV-1 infection (strains E115 and 17+), ethanol-treated cells did not produce oligonucleosomal DNA fragments characteristic of apoptosis, as assayed by gel electrophoresis and enzyme-linked immunosorbent assay. Inhibition was detected 2 h after infection and increased over time. Importantly, HSV-1-infected cells were resistant to apoptosis induced by antigen-specific CD4+ CTL, despite the fact that CTL recognition and degranulation in response to infected targets remained intact. Unlike HSV-1, HSV-2 (strains 333 and HG52) did not inhibit DNA fragmentation. In contrast to the inhibition of DNA fragmentation by HSV-1, none of the HSV-1 or -2 strains interfered with the ethanol-induced exposure of surface phosphatidylserine characteristic of apoptosis, as determined by annexin V binding. These results demonstrate that genes of HSV-1 inhibit the nuclear manifestations of apoptosis but not the membrane manifestations, suggesting that these may be mediated via separate pathways. They also suggest that HSV-1 inhibition of CTL-induced apoptosis may be an important mechanism of immune evasion.

Severe genital herpes infections in HIV-infected individuals with impaired herpes simplex virus-specific CD8+ cytotoxic T lymphocyte responses

The specific mechanisms underlying the varied susceptibility of HIV-infected (HIV+) individuals to opportunistic infections (OI) are still incompletely understood. One hypothesis is that quantitative differences in specific T cell responses to a colonizing organism determine the development of an AIDS-defining OI. We evaluated this hypothesis for herpes simplex virus (HSV) infection, a common OI in HIV+ patients. Using limiting dilution analyses, the frequency of HSV-specific CD8+ cytotoxic T lymphocyte precursors (pCTL) and proliferative precursors were quantitated in peripheral blood mononuclear cells from 20 patients coinfected with HIV and HSV-2. The frequency of HSV-specific CD8+ pCTL in HSV+HIV+ individuals was significantly lower than in HSV+HIV- individuals (1 in 77,000 vs. 1 in 6,000, P = .0005) and was not different than in HSV-HIV- individuals (1 in 100,000, P = .24). HIV+ patients who suffered more severe genital herpes recurrences had significantly lower HSV-specific CD8+ pCTL frequencies than those patients with mild recurrences (1 in 170,000 vs. 1 in 26,000, P = .03). In contrast, no significant difference was seen in proliferative precursor frequencies between those patients with mild vs. severe genital herpes (1 in 3,800 vs. 1 in 6,600, P > .5). Quantitative differences in pCTL frequency to HSV appear to be the most important host factor influencing the frequency and severity of HSV reactivation in HIV+ patients. Studies to reconstitute such immunity, especially in people with acyclovir-resistant HSV, appear warranted.

Transmissible Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) in saliva of men with a history of Kaposi's sarcoma

We have evaluated the physical state and infectious nature of Kaposi's sarcoma-associated herpesvirus (KSHV) in the saliva of nine persons with past or current Kaposi's sarcoma (KS). KSHV DNA in saliva had the physical characteristics of DNA present in virions. Inoculation of 293 cells with cell-free saliva fluid resulted in the persistence of KSHV DNA in culture for at least 13 passages of the cells. The addition of tetradecanoyl phorbol acetate to KSHV-infected 293 cells led to increased viral DNA. Two virus-specific RNAs were detected by reverse transcriptase PCR in 293 cells infected with cell-free saliva fluid and in cells present in saliva from subjects with KSHV salivary shedding. These results indicate that infectious KSHV can be present in saliva of patients with KS.

Frequent detection of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) DNA in saliva of human immunodeficiency virus-infected men: clinical and immunologic correlates

The prevalence, quantity, temporal pattern, and clinical and immunologic correlates of shedding of Kaposi's sarcoma (KS)-associated herpesvirus (KSHV; or human herpesvirus [HHV]-8) DNA in saliva were studied. KSHV DNA was detected in saliva from 18 (75%) of 24 human immunodeficiency virus (HIV)-positive patients with KS and from 1 of 1 HIV-negative patient with KS, 3 (15%) of 20 HIV-positive patients without KS, and none of 24 controls. KSHV DNA levels ranged from 10(2.4) to 10(6) copies/mL and were lower than levels for Epstein-Barr virus but comparable to those for HHV-6. Detection of KSHV DNA in saliva was not associated with oral KS or decreased peripheral blood CD4 cell counts. KSHV DNA was not detected in semen. Resistance of KSHV DNA from saliva to DNase treatment was consistent with the presence of virions. These data suggest that KSHV can replicate in the oropharynx and that salivary contact could contribute to KSHV transmission.

Preferential presentation of herpes simplex virus T-cell antigen by HLA DQA1*0501/DQB1*0201 in comparison to HLA DQA1*0201/DQB1*0201

The HLA DQA1 locus is polymorphic. Haplotypes containing HLA DQA1*0501, but not HLA DQA1*0201, together with HLA DQB1*0201 are associated with Grave's disease and celiac sprue. In this report, we demonstrate a functional correlate of DQA1 polymorphism. T cells infiltrating a herpes simplex virus (HSV) lesion from a HLA DQ 2,7 individual yielded a virus-specific CD4+ clone restricted by DQ2. Presentation of viral peptide and protein segregated with DQA1 allele, because cell lines bearing DQA1*0501/DQB1*0201 heterodimers presented antigen in proliferation and cytotoxicity assays much more efficiently than cell lines bearing DQA1*0201/DQB1*0201. Binding of viral peptide to cell lines bearing DQA1*0201, in comparison to DQA1*0501, was only moderately reduced and may not explain this effect. Truncation and substitution analyses of peptide binding and T-cell activation were performed to determine which viral peptide residues contacting TCR might therefore be presented in an altered conformation by DQA1*0201/DQB1*0201. Residues 432, 435, 437, 438, and 440 (position P1, P4, P6, P7, and P9) contributed to DQ2 binding, whereas residues 431, 433, 434, and 436 (positions P 1, P2, P3, and P5) contributed to TCR contact. Differential presentation of peptide by HLA DQ2 heterodimers varying at the DQA1 locus may have relevance to host defense and the pathogenesis of HLA DQ2-associated autoimmune diseases.

High frequency of CD8+ cytotoxic T-lymphocyte precursors specific for herpes simplex viruses in persons with genital herpes

Herpes simplex virus (HSV)-specific CD8+ cytotoxic T lymphocytes (CTL) have rarely been detected in humans, presumably because of virus-induced mechanisms that downregulate major histocompatibility complex class I expression. We have developed a method that has allowed us to consistently demonstrate HSV-specific CD8+ precursor CTL (pCTL) from HSV type 1- and 2-seropositive persons. Major histocompatibility complex-restricted HSV-specific CD8+ pCTL were found in 10 consecutively tested HSV type 1- and 2-seropositive subjects at frequencies ranging from 1 in 21,000 to 1 in 300 (median, 1 in 6,000) versus a pCTL frequency of 1 in 100,000 in HSV-seronegative donors. These results suggest that CD8+ CTL are important effector cells in resolving HSV lesions.

HLA-DQB1 codon 57 is critical for peptide binding and recognition

The association of specific HLA-DQ alleles with autoimmunity is correlated with discrete polymorphisms in the HLA-DQ sequence that are localized within sites suitable for peptide recognition. The polymorphism at residue 57 of the DQB1 polypeptide is of particular interest since it may play a major structural role in the formation of a salt bridge structure at one end of the peptide-binding cleft of the DQ molecules. This polymorphism at residue 57 is a recurrent feature of HLA-DQ evolution, occurring in multiple distinct allelic families, which implies a functional selection for maintaining variation at this position in the class II molecule. We directly tested the amino acid polymorphism at this site as a determinant for peptide binding and for antigen-specific T cell stimulation. We found that a single Ala-->Asp amino acid 57 substitution in an HLA-DQ3.2 molecule regulated binding of an HSV-2 VP-16-derived peptide. A complementary single-residue substitution in the peptide abolished its binding to DQ3.2 and converted it to a peptide that can bind to DQ3.1 and DQ3.3 Asp-57-positive MHC molecules. These binding studies were paralleled by specific T cell recognition of the class II-peptide complex, in which the substituted peptide abolished T cell reactivity, which was directed to the DQ3.2-peptide complex, whereas the same T cell clone recognized the substituted peptide presented by DQ3.3, a class II restriction element differing from DQ3.2 only at residue 57. This structural and functional complementarity for residue 57 and a specific peptide residue identifies this interaction as a key controlling determinant of restricted recognition in HLA-DQ-specific immune response.

Primary and secondary syphilis lesions contain mRNA for Th1 cytokines

Phagocytosis of Treponema pallidum by cytokine-activated macrophages aids bacterial clearance and lesion resolution in early syphilis. To investigate the cytokine profiles of cells infiltrating primary and secondary syphilis lesions, reverse transcription and polymerase chain reaction (RT-PCR) were used to detect cytokine mRNA in 13 lesion biopsies. Both primary and secondary lesions contained mRNA encoding interleukin (IL)-2, interferon-gamma (IFN-gamma), IL-12p40, and IL-10. In contrast to a lesion from a patient with recurrent herpes simplex virus type 2, no message for IL-4 could be detected in any of the syphilis lesions, and 10 of 13 had no mRNA for IL-5 or IL-13. These findings are consistent with a Th1-predominant local cellular response activating macrophages and support the hypothesis that IFN-gamma-activated macrophages are primary effectors in treponeme clearance.

Direct recovery of herpes simplex virus (HSV)-specific T lymphocyte clones from recurrent genital HSV-2 lesions

T lymphocytes were recovered from recurrent vesicular and ulcerative herpes simplex virus type 2 (HSV-2) lesions from 4 patients and cloned without exogenous secondary antigenic stimulation. Resultant cultures were screened for antigen-specific proliferative and cytotoxic responses. Of the 39 HSV-specific clones recovered, all were CD3-positive; 38 were CD4-positive and 1 was CD8-positive. Of the T cell clones recovered directly from lesions, 6%-10% had HSV-specific proliferative responses, in contrast to a peripheral blood precursor frequency of HSV-specific CD4 cells of approximately 1/10(3) to 1/10(4) as measured by limiting dilution assays. CD4+ clones studied restricted by HLA-DR, -DP, and -DQ were detected and both type-common and type-specific CD4+ T cell clones were recovered. HSV-specific T cells localize to recurrent human genital HSV-2 lesions and can be obtained directly from early lesions. The ability to isolate HSV-specific T cell clones from lesions allows the study of antigenic specificities and functional properties of tissue-resident antigen-specific T lymphocytes.

Antigenic specificities of human CD4+ T-cell clones recovered from recurrent genital herpes simplex virus type 2 lesions

Lesions resulting from recurrent genital herpes simplex virus (HSV) infection are characterized by infiltration of CD4+ lymphocytes. We have investigated the antigenic specificity of 47 HSV-specific CD4+ T-cell clones recovered from the HSV-2 buttock and thigh lesions of five patients. Clones with proliferative responses to recombinant truncated glycoprotein B (gB) or gD of HSV-2 or purified natural gC of HSV-2 comprised a minority of the total number of HSV-specific clones isolated from lesions. The gC2- and gD2-specific CD4+ clones had cytotoxic activity. The approximate locations of the HSV-2 genes encoding HSV-2 type-specific CD4+ antigens have been determined by using HSV-1 x HSV-2 intertypic recombinant virus and include the approximate map regions 0.30 to 0.46, 0.59 to 0.67, 0.67 to 0.73, and 0.82 to 1.0 units. The antigenic specificity of an HLA DQ2-restricted, HSV-2 type-specific T-cell clone was mapped to amino acids 425 to 444 of VP16 of HSV-2 by sequential use of an intertypic recombinant virus containing VP16 of HSV-2 in an HSV-1 background, recombinant VP16 fusion proteins, and synthetic peptides. Each of the remaining four patients also yielded at least one type-specific T-cell clone reactive with an HSV-2 epitope mapping to approximately 0.67 to 0.73 map units. The antigenic specificities of lesion-derived CD4+ T-cell clones are quite diverse and include at least 10 epitopes. Human T-cell clones reactive with gC and VP16 are reported here for the first time.

Herpes simplex virus infection of human fibroblasts and keratinocytes inhibits recognition by cloned CD8+ cytotoxic T lymphocytes

CD8+ cytotoxic T lymphocytes (CTL) clones with specificity for herpes simplex virus (HSV) were derived from two donors with genital HSV-2 infection. These CTL clones specifically lysed HSV-infected autologous B lymphoblastoid cells, but not HSV-infected fibroblasts. Exogenous peptide loading sensitized both cell types to lysis by an HSV-specific CTL clone of known specificity. HSV infection rendered fibroblasts refractory to peptide sensitization. HSV infection also rendered fibroblasts and keratinocytes insensitive to lysis by allospecific CD8+ CTL clones. Lysis of B lymphoblastoid cells in this system was only slightly reduced by HSV infection. Reduction of fibroblast allospecific lysis was dose and time dependent and was blocked by acyclovir, indicating the involvement of a late HSV gene product. HSV caused a reduction of fibroblast cell surface HLA class I antigen, at least in part due to reduction of synthesis of heavy chain-beta 2 microglobulin heterodimers. These results suggest that HSV-induced blockade of antigen presentation by cutaneous cells to CD8+ CTL may be a mechanism by which HSV limits or evades the immune response of the host.

Asymptomatic reactivation of herpes simplex virus in women after the first episode of genital herpes

OBJECTIVE

To determine frequency, anatomic site, and host factors associated with asymptomatic shedding of herpes simplex virus after initial episodes of genital herpes.

DESIGN

Cohort study with follow-up for a median of 63 weeks.

SETTING

Referral clinic.

PATIENTS

Women (306) with first episode of herpes; 43 had primary herpes simplex virus type 1, and 227 and 36 had primary and nonprimary herpes simplex virus type 2, respectively.

MEASUREMENTS

Cultures were obtained for herpes simplex virus every 4 to 6 weeks at times in which genital lesions and symptoms were not present.

MAIN RESULTS

Asymptomatic shedding was detected among 11.9%, 18.3%, and 22.9% of women with primary herpes simplex virus type 1, primary HSV type 2, and nonprimary HSV type 2, respectively. Among patients with type 2 infection, previous type 1 antibody was associated with a lower rate of asymptomatic vulvar shedding. Asymptomatic cervical shedding was 3 times more frequent during the first three months after resolution of primary type 2 disease than during later time periods. In contrast, the rate of symptomatic recurrent herpes did not change over time.

CONCLUSIONS

Asymptomatic genital herpes simplex type 2 is more common than type 1. Asymptomatic genital shedding occurs more often during the first 3 months after acquisition of primary type 2 disease than during later periods. Patients with HSV type 2 should be advised of this high early rate of asymptomatic shedding and of potential transmission to sexual partners.