Treponema pallidum periplasmic and membrane proteins are recognized by circulating and skin CD4+ T cells.

Background: Histologic and serologic studies suggest the induction of local and systemic Treponema pallidum ( Tp )-specific CD4+ T cell responses to Tp infection. We hypothesized that Tp -specific CD4+ T cells are detectable in blood and in the skin rash of secondary syphilis and persist in both compartments after treatment. Methods: PBMC collected from 67 participants were screened by IFNγ ELISPOT response to Tp sonicate. Tp -reactive T cell lines from blood and skin were probed for responses to 88 recombinant Tp antigens. Peptide epitopes and HLA class II restriction were defined for selected antigens. Results: We detected CD4+ T cell responses to Tp sonicate ex vivo. Using Tp -reactive T cell lines we observed recognition of 14 discrete proteins, 13 of which localize to bacterial membranes or the periplasmic space. After therapy, Tp -specific T cells persisted for at least 6 months in skin and 10 years in blood. Conclusions: Tp infection elicits an antigen-specific CD4+ T cell response in blood and skin. Tp -specific CD4+ T cells persist as memory in both compartments long after curative therapy. The Tp antigenic targets we identified may be high priority vaccine candidates.

Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Subvariant Neutralization Following a Primary Vaccine Series of NVX-CoV2373 and BNT162b2 Monovalent Booster Vaccine.

We evaluated the immunologic response to a novel vaccine regimen that included 2 doses of NVX-CoV2373 (Novavax) followed by 1 dose of BNT162b2 (Pfizer-BioNTech) monovalent booster vaccine. A durable neutralizing antibody response to Omicron BA.4/BA.5 and BA.1 variants was observed at month 6 after the booster, while immune escape was noted for the XBB.1.5 variant.

Expansion of the HSV-2-specific T cell repertoire in skin after immunotherapeutic HSV-2 vaccine.

The skin at the site of HSV-2 reactivation is enriched for HSV-2-specific T cells. To evaluate whether an immunotherapeutic vaccine could elicit skin-based memory T cells, we studied skin biopsies and HSV-2-reactive CD4+ T cells from peripheral blood mononuclear cells (PBMCs) by T cell receptor ß (TRB) sequencing before and after vaccination with a replication-incompetent whole virus HSV-2 vaccine candidate (HSV529). The representation of HSV-2-reactive CD4+ TRB sequences from PBMCs in the skin TRB repertoire increased after the first vaccine dose. We found sustained expansion after vaccination of unique, skin-based T-cell clonotypes that were not detected in HSV-2-reactive CD4+ T cells isolated from PBMCs. In one participant a switch in immunodominance occurred with the emergence of a T cell receptor (TCR) αß pair after vaccination that was not detected in blood. This TCRαß was shown to be HSV-2-reactive by expression of a synthetic TCR in a Jurkat-based NR4A1 reporter system. The skin in areas of HSV-2 reactivation possesses an oligoclonal TRB repertoire that is distinct from the circulation. Defining the influence of therapeutic vaccination on the HSV-2-specific TRB repertoire requires tissue-based evaluation.

Repeated mRNA vaccination sequentially boosts SARS-CoV-2-specific CD8+ T cells in persons with previous COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hybrid immunity is more protective than vaccination or previous infection alone. To investigate the kinetics of spike-reactive T (TS) cells from SARS-CoV-2 infection through messenger RNA vaccination in persons with hybrid immunity, we identified the T cell receptor (TCR) sequences of thousands of index TS cells and tracked their frequency in bulk TCRß repertoires sampled longitudinally from the peripheral blood of persons who had recovered from coronavirus disease 2019 (COVID-19). Vaccinations led to large expansions in memory TS cell clonotypes, most of which were CD8+ T cells, while also eliciting diverse TS cell clonotypes not observed before vaccination. TCR sequence similarity clustering identified public CD8+ and CD4+ TCR motifs associated with spike (S) specificity. Synthesis of longitudinal bulk ex vivo single-chain TCRß repertoires and paired-chain TCRÉ‘ß sequences from droplet sequencing of TS cells provides a roadmap for the rapid assessment of T cell responses to vaccines and emerging pathogens.

Recruitment of naive CD4+ T cells by the recombinant zoster vaccine correlates with persistent immunity.

Herpes zoster (HZ) is a substantial problem for people with decreased cell-mediated immunity, including older adults. The first vaccine approved for HZ prevention, the zoster vaccine live (ZVL), which provided limited and short-lived protection, has been supplanted by the superior recombinant zoster vaccine (RZV), which provides robust and durable protection. To understand the mechanisms underlying the differential immunologic characteristics of the 2 vaccines, we used T cell receptor ß chain sequencing and peptide-MHC class II tetramer staining to analyze recombinant glycoprotein E-specific (gE-specific) CD4+ T cell clonotypes in RZV and ZVL recipients. Compared with ZVL, RZV expanded more gE-specific CD4+ clonotypes, with greater breadth and higher frequency of public clonotypes. RZV recruited a higher proportion of clonotypes from naive than from memory cells, while ZVL recruited equally from memory and naive compartments. Compared with memory-derived, naive-derived clonotypes were more likely to last 5 or more years after immunization. Moreover, the frequency of tetramer+ persistent clones correlated with the frequency of tetramer+ naive CD4+ prevaccination T cells. We conclude that the ability of RZV to recruit naive CD4+ T cells into the response may contribute to the durability of its effect. The abundance, breadth, and frequency of public clonotypes may further add to its protective effect.

Varicella-zoster virus proteome-wide T-cell screening demonstrates low prevalence of virus-specific CD8 T-cells in latently infected human trigeminal ganglia.

BACKGROUND: Trigeminal ganglia (TG) neurons are an important site of lifelong latent varicella-zoster virus (VZV) infection. Although VZV-specific T-cells are considered pivotal to control virus reactivation, their protective role at the site of latency remains uncharacterized. METHODS: Paired blood and TG specimens were obtained from ten latent VZV-infected adults, of which nine were co-infected with herpes simplex virus type 1 (HSV-1). Short-term TG-derived T-cell lines (TG-TCL), generated by mitogenic stimulation of TG-derived T-cells, were probed for HSV-1- and VZV-specific T-cells using flow cytometry. We also performed VZV proteome-wide screening of TG-TCL to determine the fine antigenic specificity of VZV reactive T-cells. Finally, the relationship between T-cells and latent HSV-1 and VZV infections in TG was analyzed by reverse transcription quantitative PCR (RT-qPCR) and in situ analysis for T-cell proteins and latent viral transcripts. RESULTS: VZV proteome-wide analysis of ten TG-TCL identified two VZV antigens recognized by CD8 T-cells in two separate subjects. The first was an HSV-1/VZV cross-reactive CD8 T-cell epitope, whereas the second TG harbored CD8 T-cells reactive with VZV specifically and not the homologous peptide in HSV-1. In silico analysis showed that HSV-1/VZV cross reactivity of TG-derived CD8 T-cells reactive with ten previously identified HSV-1 epitopes was unlikely, suggesting that HSV-1/VZV cross-reactive T-cells are not a common feature in dually infected TG. Finally, no association was detected between T-cell infiltration and VZV latency transcript abundance in TG by RT-qPCR or in situ analyses. CONCLUSIONS: The low presence of VZV- compared to HSV-1-specific CD8 T-cells in human TG suggests that VZV reactive CD8 T-cells play a limited role in maintaining VZV latency.

Diminished humoral and cellular responses to SARS-CoV-2 vaccines in patients with chronic lymphocytic leukemia.

Previous studies have demonstrated low rates of seroconversion to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines in patients with chronic lymphocytic leukemia (CLL). In this national collaboration of 11 cancer centers in the United States, we aimed to further characterize and understand vaccine-induced immune responses, including T-cell responses, and the impact of CLL therapeutics (#NCT04852822). Eligible patients were enrolled in 2 cohorts (1) at the time of initial vaccination and (2) at the time of booster vaccination. The serologic response rates (anti-S) from 210 patients in the initial vaccination cohort and 117 in the booster vaccination cohort were 56% (95% confidence interval [CI], 50-63) and 68% (95% CI, 60-77), respectively. Compared with patients not on therapy, those receiving B-cell-directed therapy were less likely to seroconvert (odds ratio [OR], 0.27; 95% CI, 0.15-0.49). Persistence of response was observed at 6 months; anti-S titers increased with the administration of booster vaccinations. In the initial vaccination cohort, positive correlations were observed between the quantitative serologic response and CD4 T-cell response for the Wuhan variant and, to a lesser degree, for the Omicron variant (Spearman P = 0.45 Wuhan; P = 0.25 Omicron). In the booster vaccination cohort, positive correlations were observed between serologic responses and CD4 T-cell responses for both variants (P = 0.58 Wuhan; P = 0.57 Omicron) and to a lesser degree for CD8 T-cell responses (P = 0.33 Wuhan; P = 0.22 Omicron). Although no deaths from coronavirus disease 2019 (COVID-19) have been reported after booster vaccinations, patients should use caution as newer variants emerge and escape vaccine-induced immunity. This trial was registered at www.clinicaltrials.gov as #NCT04852822.

Selective retention of virus-specific tissue-resident T cells in healed skin after recovery from herpes zoster.

Herpes zoster is a localized skin infection caused by reactivation of latent varicella-zoster virus. Tissue-resident T cells likely control skin infections. Zoster provides a unique opportunity to determine if focal reinfection of human skin boosts local or disseminated antigen-specific tissue-resident T cells. Here, we show virus-specific T cells are retained over one year in serial samples of rash site and contralateral unaffected skin of individuals recovered from zoster. Consistent with zoster resolution, viral DNA is largely undetectable on skin from day 90 and virus-specific B and T cells decline in blood. In skin, there is selective infiltration and long-term persistence of varicella-zoster virus-specific T cells in the rash site relative to the contralateral site. The skin T cell infiltrates express the canonical tissue-resident T cell markers CD69 and CD103. These findings show that zoster promotes spatially-restricted long-term retention of antigen-specific tissue-resident T cells in previously infected skin.

HLA-B*57:01 Complexed to a CD8 T-Cell Epitope from the HSV-2 ICP22 Protein Binds NK and T Cells through KIR3DL1.

HLA-B*57:01 is an HLA allelic variant associated with positive outcomes during viral infections through interactions with T cells and NK cells, but severe disease in persons treated with the anti-HIV-1 drug abacavir. The role of HLA-B*57:01 in the context of HSV infection is unknown. We identified an HLA-B*57:01-restricted CD8 T-cell epitope in the ICP22 (US1) protein of HSV-2. CD8 T cells reactive to the HSV-2 ICP22 epitope recognized the orthologous HSV-1 peptide, but not closely related peptides in human IFNL2 or IFNL3. Abacavir did not alter the CD8 T-cell recognition of the HSV or self-derived peptides. Unexpectedly, a tetramer of HSV-2 ICP22 epitope (228-236) and HLA-B*57:01 bound both CD8 T cells and NK cells. Tetramer specificity for KIR3DL1 was confirmed using KIR3DL1 overexpression on non-human primate cells lacking human KIR and studies with blocking anti-KIR3DL1 antibody. Interaction with KIR3DL1 was generalizable to donors lacking the HLA-B*57:01 genotype or HSV seropositivity. These findings suggest a mechanism for the recognition of HSV infection by NK cells or KIR-expressing T cells via KIR3DL1.

HSV-2-Specific Human Female Reproductive Tract Tissue Resident Memory T Cells Recognize Diverse HSV Antigens.

Antigen-specific TRM persist and protect against skin or female reproductive tract (FRT) HSV infection. As the pathogenesis of HSV differs between humans and model organisms, we focus on humans with well-characterized recurrent genital HSV-2 infection. Human CD8+ TRM persisting at sites of healed human HSV-2 lesions have an activated phenotype but it is unclear if TRM can be cultivated in vitro. We recovered HSV-specific TRM from genital skin and ectocervix biopsies, obtained after recovery from recurrent genital HSV-2, using ex vivo activation by viral antigen. Up to several percent of local T cells were HSV-reactive ex vivo. CD4 and CD8 T cell lines were up to 50% HSV-2-specific after sorting-based enrichment. CD8 TRM displayed HLA-restricted reactivity to specific HSV-2 peptides with high functional avidities. Reactivity to defined peptides persisted locally over several month and was quite subject-specific. CD4 TRM derived from biopsies, and from an extended set of cervical cytobrush specimens, also recognized diverse HSV-2 antigens and peptides. Overall we found that HSV-2-specific TRM are abundant in the FRT between episodes of recurrent genital herpes and maintain competency for expansion. Mucosal sites are accessible for clinical monitoring during immune interventions such as therapeutic vaccination.

BTK inhibitors impair humoral and cellular responses to recombinant zoster vaccine in CLL.

Vaccinations effectively prevent infections; however, patients with chronic lymphocytic leukemia (CLL) have reduced antibody responses following vaccinations. Combined humoral and cellular immune responses to novel adjuvanted vaccines are not well characterized in CLL. In an open-label, single-arm clinical trial, we measured the humoral and cellular immunogenicity of the recombinant zoster vaccine (RZV) in CLL patients who were treatment naïve (TN) or receiving Bruton tyrosine kinase inhibitor (BTKi) therapy. The primary endpoint was antibody response to RZV (≥fourfold increase in anti-glycoprotein E [anti-gE]). Cellular response of gE-specific CD4+ T cells was assessed by flow cytometry for upregulation of ≥2 effector molecules. The antibody response rate was significantly higher in the TN cohort (76.8%; 95% confidence interval [CI], 65.7-87.8) compared with patients receiving a BTKi (40.0%; 95% CI, 26.4-53.6; P = .0002). The cellular response rate was also significantly higher in the TN cohort (70.0%; 95% CI, 57.3-82.7) compared with the BTKi group (41.3%; 95% CI, 27.1-55.5; P = .0072). A concordant positive humoral and cellular immune response was observed in 69.1% (95% CI, 56.9-81.3) of subjects with a humoral response, whereas 39.0% (95% CI, 24.1-54.0) of subjects without a humoral response attained a cellular immune response (P = .0033). Antibody titers and T-cell responses were not correlated with age, absolute B- and T-cell counts, or serum immunoglobulin levels (all P > .05). RZV induced both humoral and cellular immune responses in treated and untreated CLL patients, albeit with lower response rates in patients on BTKi therapy compared with TN patients. This trial was registered at www.clinicaltrials.gov as #NCT03702231.

T cell response to intact SARS-CoV-2 includes coronavirus cross-reactive and variant-specific components.

SARS-CoV-2 provokes a brisk T cell response. Peptide-based studies exclude antigen processing and presentation biology and may influence T cell detection studies. To focus on responses to whole virus and complex antigens, we used intact SARS-CoV-2 and full-length proteins with DC to activate CD8 and CD4 T cells from convalescent persons. T cell receptor (TCR) sequencing showed partial repertoire preservation after expansion. Resultant CD8 T cells recognize SARS-CoV-2-infected respiratory cells, and CD4 T cells detect inactivated whole viral antigen. Specificity scans with proteome-covering protein/peptide arrays show that CD8 T cells are oligospecific per subject and that CD4 T cell breadth is higher. Some CD4 T cell lines enriched using SARS-CoV-2 cross-recognize whole seasonal coronavirus (sCoV) antigens, with protein, peptide, and HLA restriction validation. Conversely, recognition of some epitopes is eliminated for SARS-CoV-2 variants, including spike (S) epitopes in the alpha, beta, gamma, and delta variant lineages.

T cell response to intact SARS-CoV-2 includes coronavirus cross-reactive and variant-specific components.

SARS-CoV-2 provokes a robust T cell response. Peptide-based studies exclude antigen processing and presentation biology, which may influence T cell detection studies. To focus on responses to whole virus and complex antigens, we used intact SARS-CoV-2 and full-length proteins with DCs to activate CD8 and CD4 T cells from convalescent people. T cell receptor (TCR) sequencing showed partial repertoire preservation after expansion. Resultant CD8 T cells recognize SARS-CoV-2-infected respiratory tract cells, and CD4 T cells detect inactivated whole viral antigen. Specificity scans with proteome-covering protein/peptide arrays show that CD8 T cells are oligospecific per subject and that CD4 T cell breadth is higher. Some CD4 T cell lines enriched using SARS-CoV-2 cross-recognize whole seasonal coronavirus (sCoV) antigens, with protein, peptide, and HLA restriction validation. Conversely, recognition of some epitopes is eliminated for SARS-CoV-2 variants, including spike (S) epitopes in the Alpha, Beta, Gamma, and Delta variant lineages.

Distinct populations of antigen-specific tissue-resident CD8+ T cells in human cervix mucosa.

The ectocervix is part of the lower female reproductive tract (FRT), which is susceptible to sexually transmitted infections (STIs). Comprehensive knowledge of the phenotypes and T cell receptor (TCR) repertoire of tissue-resident memory T cells (TRMs) in the human FRT is lacking. We took single-cell RNA-Seq approaches to simultaneously define gene expression and TCR clonotypes of the human ectocervix. There were significantly more CD8+ than CD4+ T cells. Unsupervised clustering and trajectory analysis identified distinct populations of CD8+ T cells with IFNGhiGZMBloCD69hiCD103lo or IFNGloGZMBhiCD69medCD103hi phenotypes. Little overlap was seen between their TCR repertoires. Immunofluorescence staining showed that CD103+CD8+ TRMs were preferentially localized in the epithelium, whereas CD69+CD8+ TRMs were distributed evenly in the epithelium and stroma. Ex vivo assays indicated that up to 14% of cervical CD8+ TRM clonotypes were HSV-2 reactive in HSV-2-seropositive persons, reflecting physiologically relevant localization. Our studies identified subgroups of CD8+ TRMs in the human ectocervix that exhibited distinct expression of antiviral defense and tissue residency markers, anatomic locations, and TCR repertoires that target anatomically relevant viral antigens. Optimization of the location, number, and function of FRT TRMs is an important approach for improving host defenses to STIs.

Proteome-Wide Zika Virus CD4 T Cell Epitope and HLA Restriction Determination.

Zika virus (ZIKV) is a mosquito-borne pathogen that caused an epidemic in 2015-2016. ZIKV-specific T cell responses are functional in animal infection models, and helper CD4 T cells promote avid Abs in the vaccine context. The small volumes of blood available from field research limit the determination of T cell epitopes for complex microbes such as ZIKV. The goal of this project was efficient determination of human ZIKV CD4 T cell epitopes at the whole proteome scale, including validation of reactivity to whole pathogen, using small blood samples from convalescent time points when T cell response magnitude may have waned. Polyclonal enrichment of candidate ZIKV-specific CD4 T cells used cell-associated virus, documenting that T cells in downstream peptide analyses also recognize whole virus after Ag processing. Sequential query of bulk ZIKV-reactive CD4 T cells with pooled/single ZIKV peptides and molecularly defined APC allowed precision epitope and HLA restriction assignments across the ZIKV proteome and enabled discovery of numerous novel ZIKV CD4 T cell epitopes. The research workflow is useful for the study of emerging infectious diseases with a very limited human blood sample availability.

Immune responses to a HSV-2 polynucleotide immunotherapy COR-1 in HSV-2 positive subjects: A randomized double blinded phase I/IIa trial.

BACKGROUND: Genital herpes simplex infection affects more than 500 million people worldwide. We have previously shown that COR-1, a therapeutic HSV-2 polynucleotide vaccine candidate, is safe and well tolerated in healthy subjects. OBJECTIVE: Here, we present a single center double-blind placebo-controlled, randomized phase I/IIa trial of COR-1 in HSV-2 positive subjects in which we assessed safety and tolerability as primary endpoints, and immunogenicity and therapeutic efficacy as exploratory endpoints. METHODS: Forty-four HSV-2+ subjects confirmed by positive serology or pathology, and positive qPCR during baseline shedding, with a recurrent genital HSV-2 history of at least 12 months including three to nine reported lesions in 12 months prior to screening, aged 18 to 50 years females and males with given written informed consent, were randomized into two groups. Three immunizations at 4-week intervals and one booster immunization at 6 months, each of 1 mg COR-1 DNA or placebo, were administered intradermally as two injections of 500 µg each to either one forearm or both forearms. RESULTS: No serious adverse events, life-threatening events or deaths occurred throughout the study. As expected, HSV-2 infected subjects displayed gD2-specific antibody titers prior to immunization. COR-1 was associated with a reduction in viral shedding after booster administration compared with baseline. CONCLUSIONS: This study confirms the previously demonstrated safety of COR-1 in humans and indicates a potential for use of COR-1 as a therapy to reduce viral shedding in HSV-2 infected subjects.

Human CD4+ T Cells Specific for Merkel Cell Polyomavirus Localize to Merkel Cell Carcinomas and Target a Required Oncogenic Domain.

Although CD4+ T cells likely play key roles in antitumor immune responses, most immuno-oncology studies have been limited to CD8+ T-cell responses due to multiple technical barriers and a lack of shared antigens across patients. Merkel cell carcinoma (MCC) is an aggressive skin cancer caused by Merkel cell polyomavirus (MCPyV) oncoproteins in 80% of cases. Because MCPyV oncoproteins are shared across most patients with MCC, it is unusually feasible to identify, characterize, and potentially augment tumor-specific CD4+ T cells. Here, we report the identification of CD4+ T-cell responses against six MCPyV epitopes, one of which included a conserved, essential viral oncogenic domain that binds/disables the cellular retinoblastoma (Rb) tumor suppressor. We found that this epitope (WEDLT209-228) could be presented by three population-prevalent HLA class II alleles, making it a relevant target in 64% of virus-positive MCC patients. Cellular staining with a WEDLT209-228-HLA-DRB1*0401 tetramer indicated that specific CD4+ T cells were detectable in 78% (14 of 18) of evaluable MCC patients, were 250-fold enriched within MCC tumors relative to peripheral blood, and had diverse T-cell receptor sequences. We also identified a modification of this domain that still allowed recognition by these CD4+ T cells but disabled binding to the Rb tumor suppressor, a key step in the detoxification of a possible therapeutic vaccine. The use of these new tools for deeper study of MCPyV-specific CD4+ T cells may provide broader insight into cancer-specific CD4+ T-cell responses.

A Randomized, Double-Blinded, Placebo-Controlled, Phase 1 Study of a Replication-Defective Herpes Simplex Virus (HSV) Type 2 Vaccine, HSV529, in Adults With or Without HSV Infection.

BACKGROUND: Herpes simplex virus 2 (HSV2) causes genital herpes in >400 million persons worldwide. METHODS: We conducted a randomized, double-blinded, placebo-controlled trial of a replication-defective HSV2 vaccine, HSV529. Twenty adults were enrolled in each of 3 serogroups of individuals: those negative for both HSV1 and HSV2 (HSV1-/HSV2-), those positive or negative for HSV1 and positive for HSV2 (HSV1±/HSV2+), and those positive for HSV1 and negative for HSV2 (HSV1+/HSV2-). Sixty participants received vaccine or placebo at 0, 1, and 6 months. The primary end point was the frequency of solicited local and systemic reactions to vaccination. RESULTS: Eighty-nine percent of vaccinees experienced mild-to-moderate solicited injection site reactions, compared with 47% of placebo recipients (95% confidence interval [CI], 12.9%-67.6%; P = .006). Sixty-four percent of vaccinees experienced systemic reactions, compared with 53% of placebo recipients (95% CI, -17.9% to 40.2%; P = .44). Seventy-eight percent of HSV1-/HSV2- vaccine recipients had a ≥4-fold increase in neutralizing antibody titer after 3 doses of vaccine, whereas none of the participants in the other serogroups had such responses. HSV2-specific CD4+ T-cell responses were detected in 36%, 46%, and 27% of HSV1-/HSV2-, HSV1±/HSV2+, and HSV1+/HSV2- participants, respectively, 1 month after the third dose of vaccine, and CD8+ T-cell responses were detected in 14%, 8%, and 18% of participants, respectively. CONCLUSIONS: HSV529 vaccine was safe and elicited neutralizing antibody and modest CD4+ T-cell responses in HSV-seronegative vaccinees. CLINICAL TRIALS REGISTRATION: NCT01915212.

Viral Genetics Modulate Orolabial Herpes Simplex Virus Type 1 Shedding in Humans.

BACKGROUND: Orolabial herpes simplex virus type 1 (HSV-1) infection has a wide spectrum of severity in immunocompetent persons. To study the role of viral genotype and host immunity, we characterized oral HSV-1 shedding rates and host cellular response, and genotyped viral strains, in monozygotic (MZ) and dizygotic (DZ) twins. METHODS: A total of 29 MZ and 22 DZ HSV-1-seropositive twin pairs were evaluated for oral HSV-1 shedding for 60 days. HSV-1 strains from twins were genotyped as identical or different. CD4+ T-cell responses to HSV-1 proteins were studied. RESULTS: The median per person oral HSV shedding rate was 9% of days that a swab was obtained (mean, 10.2% of days). A positive correlation between shedding rates was observed within all twin pairs, and in the MZ and DZ twins. In twin subsets with sufficient HSV-1 DNA to genotype, 15 had the same strain and 14 had different strains. Viral shedding rates were correlated for those with the same but not different strains. The median number of HSV-1 open reading frames recognized per person was 16. The agreement in the CD4+ T-cell response to specific HSV-1 open reading frames was greater between MZ twins than between unrelated persons (P = .002). CONCLUSION: Viral strain characteristics likely contribute to oral HSV-1 shedding rates.

Immunobiology of Varicella-Zoster Virus Infection.

Varicella-zoster virus (VZV) causes clinically significant illness during acute and recurrent infection accompanied by robust innate and acquired immune responses. Innate immune cells in skin and ganglion secrete type I interferon (IFN-I) and proinflammatory cytokines to control VZV. Varicella-zoster virus subverts pattern recognition receptor sensing to modulate antigen presentation and IFN-I production. During primary infection, VZV hijacks T cells to disseminate to the skin and establishes latency in ganglia. Durable T- and B-cell memory formed within a few weeks of infection is boosted by reactivation or re-exposure. Antigen-specific T cells are recruited and potentially retained in VZV-infected skin to counteract reactivation. In latently VZV-infected ganglia, however, virus-specific T cells have not been recovered, suggesting that local innate immune responses control VZV latency. Antibodies prevent primary VZV infection, whereas T cells are fundamental to resolving disease, limiting severity, and preventing reactivation. In this study, we review current knowledge on the interactions between VZV and the human immune system.