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.

Prior Herpes Simplex Virus Infection and the Risk of Herpes Zoster.

BACKGROUND: The incidence of herpes zoster (HZ) has increased in the United States concurrent with decrease in herpes simplex virus (HSV) prevalence. We hypothesized that lack of HSV-elicited cross-reactive immunity to varicella-zoster virus (VZV) results in an increased risk of HZ. Using specimens from the placebo arm of the Shingles Prevention Study, we investigated whether persons who develop HZ are less likely to have prior HSV infection than persons who do not develop HZ, and whether HZ is less severe in persons with HSV than in HSV seronegative persons. METHODS: We conducted a nested case-control (1:2) study comparing the seroprevalence of HSV-1 and HSV-2 in cases (persons with polymerase chain reaction-confirmed HZ) to age-, sex-, and health-matched controls (persons without HZ). RESULTS: Sera from 639 study participants (213 cases and 426 controls) yielded definitive HSV antibody results and were analyzed. Overall, HSV seropositivity rate was 75%. HSV seronegativity was significantly higher in HZ cases than controls (30.5% vs 22.3%; P = .024), with a 55% higher risk of HZ in HSV seronegative than HSV seropositive participants. HSV seropositivity was associated with more severe HZ (P = .021). CONCLUSIONS: Our study demonstrated that prior infection with HSV partly protects against HZ.

Viral genomic variation and the severity of genital HSV-2 infection as quantified by shedding rate: a viral genome-wide association study.

BACKGROUND: The clinical severity of genital HSV-2 infection varies widely among infected persons with some experiencing frequent genital lesions while others are asymptomatic. The viral genital shedding rate is closely associated with and has been established as a surrogate marker of clinical severity. METHODS: To assess the relationship between viral genetics and shedding, we assembled a set of 145 persons who had the severity of their genital herpes quantified through determination of their HSV genital shedding rate. An HSV-2 sample from each person was sequenced and biallelic variants among these genomes were identified. RESULTS: We found no association between metrics of genome-wide variation in HSV-2 and shedding rate. A viral genome-wide association study (vGWAS) identified the minor alleles of three individual unlinked variants as significantly associated with higher shedding rate (p<8.4x10-5): C44973T (A512T), a non-synonymous variant in UL22 (glycoprotein H); A74534G, a synonymous variant in UL36 (large tegument protein); and T119283C, an intergenic variant. We also found an association between the total number of minor alleles for the significant variants and shedding rate (p=6.6x10-7). CONCLUSIONS: These results add to a growing body of literature for HSV suggesting a connection between viral genetic variation and clinically important phenotypes of infection.

Hybrid Immunity to SARS-CoV-2 During Pregnancy Provides More Durable Infant Antibody Responses Compared to Natural Infection Alone.

BACKGROUND: Hybrid immunity (infection plus vaccination) may increase maternally derived SARS-CoV-2 antibody responses and durability versus infection alone. METHODS: Prospective cohort of pregnant participants with prior SARS-CoV-2 infection (anti-nucleocapsid IgG, RT-PCR, or antigen positive) and their infants had blood collected in pregnancy, at delivery/birth, and postpartum tested for anti-spike (anti-S) IgG and neutralizing antibodies (neutAb). RESULTS: Among 107 participants at enrollment, 40% were unvaccinated and 60% were vaccinated (received ≥1 dose); 102 had previous SARS-CoV-2 infection in pregnancy (median, 19 weeks' gestation); 5 were diagnosed just prior to pregnancy (median, 8 weeks). At delivery, fewer unvaccinated participants (87% anti-S IgG+, 86% neutAb) and their infants (86% anti-S IgG+, 75% neutAb) had anti-S IgG+ or neutAb compared to vaccinated participants and their infants (100%, P ≤ .01 for all). By 3-6 months postpartum, 50% of infants of unvaccinated participants were anti-S IgG+ and 14% had neutAb, versus 100% among infants of vaccinated participants (all P < .01), with lower median antibody responses (anti-S IgG log10 1.95 vs 3.84 AU/mL, P < .01; neutAb log10 1:1.34 vs 1:3.20, P = .11). CONCLUSIONS: In pregnant people with prior SARS-CoV-2, vaccination before delivery provided more durable maternally derived antibody responses than infection alone in infants through 6 months.

Performance characteristics of highly automated HSV-1 and HSV-2 IgG testing.

Herpes simplex virus (HSV) infections are one of the most common and stigmatized infections of humankind, affecting more than 4 billion people around the world and more than 100 million Americans. Yet, most people do not know their infection status, and antibody testing is not recommended, partly due to poor test performance. Here, we compared the test performance of the Roche Elecsys HSV-1 IgG and HSV-2 IgG, DiaSorin LIAISON HSV-1/2 IgG, and Bio-Rad BioPlex 2200 HSV-1 and HSV-2 IgG assays with the gold-standard HSV western blot in 1,994 persons, including 1,017 persons with PCR or culture-confirmed HSV-1 and/or HSV-2 infection. Across all samples, the Bio-Rad and Roche assays had similar performance metrics with low sensitivity (<85%) but high specificity (>97%) for detecting HSV-1 IgG and both high sensitivity (>97%) and high specificity (>98%) for detecting HSV-2 IgG. The DiaSorin assay had a higher sensitivity (92.1%) but much lower specificity (88.7%) for detecting HSV-1 IgG and comparatively poor sensitivity (94.5%) and specificity (94.2%) for detecting HSV-2 IgG. The DiaSorin assay performed poorly at low-positive index values with 60.9% of DiaSorin HSV-1 results and 20.8% of DiaSorin HSV-2 results with positive index values <3.0 yielding false positive results. Based on an estimated HSV-2 seroprevalence of 12% in the United States, positive predictive values for HSV-2 IgG were 96.1% for Roche, 87.4% for Bio-Rad, and 69.0% for DiaSorin, meaning nearly one of every three positive DiaSorin HSV-2 IgG results would be falsely positive. Further development in HSV antibody diagnostics is needed to provide appropriate patient care.IMPORTANCESerological screening for HSV infections is currently not recommended in part due to the poor performance metrics of widely used commercial HSV-1 and HSV-2 IgG assays. Here, we compare three Food and Drug Administration (FDA)-cleared automated HSV-1 and HSV-2 IgG assays to the gold-standard western blot across nearly 2,000 samples. We find that not all commercially available HSV assays are created equal, with comparably low sensitivities for HSV-1 IgG across platforms and high false positivity rates for DiaSorin on HSV-2 IgG. This study is the first large-scale comparison of performance metrics for the Bio-Rad and Roche assays in over 10 years. Our study confirms that there remains room for improvement in HSV serological diagnostic testing-especially in regard to low sensitivities for HSV-1 IgG detection-and highlights that some previously less-studied assays may have better performance metrics than previously considered typical of commercially available HSV-2 IgG assays.

Comparison of herpes simplex virus 1 genomic diversity between adult sexual transmission partners with genital infection.

Herpes simplex virus (HSV) causes chronic infection in the human host, characterized by self-limited episodes of mucosal shedding and lesional disease, with latent infection of neuronal ganglia. The epidemiology of genital herpes has undergone a significant transformation over the past two decades, with the emergence of HSV-1 as a leading cause of first-episode genital herpes in many countries. Though dsDNA viruses are not expected to mutate quickly, it is not yet known to what degree the HSV-1 viral population in a natural host adapts over time, or how often viral population variants are transmitted between hosts. This study provides a comparative genomics analysis for 33 temporally-sampled oral and genital HSV-1 genomes derived from five adult sexual transmission pairs. We found that transmission pairs harbored consensus-level viral genomes with near-complete conservation of nucleotide identity. Examination of within-host minor variants in the viral population revealed both shared and unique patterns of genetic diversity between partners, and between anatomical niches. Additionally, genetic drift was detected from spatiotemporally separated samples in as little as three days. These data expand our prior understanding of the complex interaction between HSV-1 genomics and population dynamics after transmission to new infected persons.

Evaluation of oral herpes simplex virus shedding among solid organ transplant recipients: A pilot study.

BACKGROUND: Herpes simplex viruses (HSVs) frequently reactivate during immunosuppression and may be a risk factor for adverse outcomes after solid organ transplant (SOT). While suppressive antiviral therapy reduces the risk of symptomatic HSV reactivation, the kinetics of asymptomatic viral shedding with chronic immunosuppression after transplant are not well understood. We report the characteristics of oral HSV shedding among 15 HSV-1 seropositive SOT recipients (n = 8 liver, n = 7 kidney, median age 58.5 years, median 20 months post-transplant) who were not taking daily antiviral suppressive therapy. METHODS: Participants self-collected oral swabs three times daily for 6 weeks for HSV quantification and recorded the presence of oral symptoms or lesions in a diary. RESULTS: Sample collection adherence was high (median 122 swabs/person, range: 85.7%-101.6% of expected swabs). Most participants (n = 12, 80%) experienced at least one shedding episode, with a median shedding rate of 8.9% (range: 0%-33.6%). There were 32 total shedding episodes, 24 (75%) of which occurred without symptoms or lesions. For episodes of known duration, the median length was 21.8 hrs (interquartile range: 10.8-46.1 hrs). CONCLUSION: Most shedding episodes (78.1%) lasted >12 hrs, suggesting that twice-daily sampling may be sufficient to detect most episodes. These data show that self-collection of oral swabs is feasible for patients who have undergone SOTs and can provide insight into the frequency of oral HSV reactivation, which can be used to design future studies in this population.

Low prevalence of bacterial vaginosis in Kenyan adolescent girls and rapid incidence after first sex.

BACKGROUND: Bacterial vaginosis is a risk factor for sexually transmitted infections, including HIV. Adult African women have a high prevalence of bacterial vaginosis, but it is not known when first bacterial vaginosis occurs. OBJECTIVE: This study aimed to describe bacterial vaginosis in younger African women, before and after first sex, and to determine the incidence of bacterial vaginosis and significant correlates of bacterial vaginosis incidence and recurrence. STUDY DESIGN: In a prospective observational cohort study enrolling adolescents with limited sexual experience, young women aged 16 to 21 years were recruited in Thika, Kenya. Eligible participants were HIV and herpes simplex virus 2 seronegative and reported 0 or 1 lifetime sexual partner. The Nugent score was determined at quarterly visits from vaginal Gram stains. The trends in bacterial vaginosis were described over time; hazard ratios were calculated using Cox regression, and relative risk of bacterial vaginosis was estimated using generalized estimating equations and Poisson regression. RESULTS: A total of 400 participants with a median age of 18.6 years (interquartile range, 16-21) were enrolled. Of note, 322 participants (80.5%) reported no history of sex, whereas 78 participants (19.5%) reported sex with 1 partner. At enrollment, bacterial vaginosis (Nugent score of ≥7) was uncommon (21/375 [5.6%]). Overall, 144 participants had bacterial vaginosis at least once, for an incidence rate of 16.5 cases per 100 person-years. Before first sex, bacterial vaginosis was present at 2.8% of visits, compared with 13.7% of visits after first sex. An adjusted model of bacterial vaginosis incidence observed that first sex was associated with more than a 2-fold increased bacterial vaginosis risk (adjusted hazard ratio, 2.44; 95% confidence interval, 1.25-4.76; P=.009). Chlamydia diagnosis (adjusted hazard ratio, 1.73; 95% confidence interval, 1.1-2.8; P=.02), and herpes simplex virus 2 seropositivity (adjusted hazard ratio, 2.88; 95% confidence interval, 1.17-7.09; P=.021) were both associated with incident bacterial vaginosis. A multivariate generalized estimating equation model, including all episodes of bacterial vaginosis, demonstrated risk factors, including first sex, sexually transmitted infections, urban residence, recent sex, and no income; the most important risk factor was first sex (adjusted relative risk, 1.92; 95% confidence interval, 1.12-3.31; P=.018). The probability of bacterial vaginosis increased with each subsequent episode; mean Nugent scores increased after each bacterial vaginosis episode. CONCLUSION: Using detailed longitudinal observation, this study found that Kenyan adolescents have almost no bacterial vaginosis before first sex and that initiation of sexual activity was the strongest risk factor for both prevalent bacterial vaginosis and incident bacterial vaginosis.

Viral Shedding 1 Year Following First-Episode Genital HSV-1 Infection.

Importance: Herpes simplex virus type 1 (HSV-1) is the leading cause of first-episode genital herpes in many countries. Objective: To inform counseling messages regarding genital HSV-1 transmission, oral and genital viral shedding patterns among persons with first-episode genital HSV-1 infection were assessed. The trajectory of the development of HSV-specific antibody and T-cell responses was also characterized. Design, Setting, and Participants: Prospective cohort followed up for up to 2 years, with 82 participants followed up between 2013 and 2018. Participants were recruited from sexual health and primary care clinics in Seattle, Washington. Persons with laboratory-documented first-episode genital HSV-1 infection, without HIV infection or current pregnancy, were referred for enrollment. Exposures: First-episode genital HSV-1 infection. Main Outcomes and Measures: Genital and oral HSV-1 shedding and lesion rates at 2 months, 11 months, and up to 2 years after initial genital HSV-1 infection. Participants self-collected oral and genital swabs for HSV polymerase chain reaction testing for 30 days at 2 and 11 months and up to 2 years after diagnosis of genital HSV-1. Blood samples were collected at serial time points to assess immune responses to HSV-1. Primary HSV-1 infection was defined as absent HSV antibody at baseline or evolving antibody profile using the University of Washington HSV Western Blot. HSV-specific T-cell responses were detected using interferon γ enzyme-linked immunospot. Results: Among the 82 participants, the median (range) age was 26 (16-64) years, 54 (65.9%) were women, and 42 (51.2%) had primary HSV-1 infection. At 2 months, HSV-1 was detected from the genital tract in 53 participants (64.6%) and in the mouth in 24 participants (29.3%). Genital HSV-1 shedding was detected on 275 of 2264 days (12.1%) at 2 months and declined significantly to 122 of 1719 days (7.1%) at 11 months (model-predicted rate, 6.2% [95% CI, 4.3%-8.9%] at 2 months vs 3.2% [95% CI, 1.8%-5.7%] at 11 months; relative risk, 0.52 [95% CI, 0.29-0.93]). Genital lesions were rare, reported on 65 of 2497 days (2.6%) at 2 months and 72 of 1872 days (3.8%) at 11 months. Oral HSV-1 shedding was detected on 88 of 2247 days (3.9%) at 2 months. Persons with primary HSV-1 infection had a higher risk of genital shedding compared with those with nonprimary infection (model-predicted rate, 7.9% [95% CI, 5.4%-11.7%] vs 2.9% [95% CI, 1.7%-5.0%]; relative risk, 2.75 [95% CI, 1.40-5.44]). Polyfunctional HSV-specific CD4+ and CD8+ T-cell responses were maintained during the follow-up period. Conclusions and Relevance: Genital HSV-1 shedding was frequent after first-episode genital HSV-1, particularly among those with primary infection, and declined rapidly during the first year after infection.

Subclinical Genital Herpes Shedding in HIV/Herpes Simplex Virus 2-Coinfected Women during Antiretroviral Therapy Is Associated with an Increase in HIV Tissue Reservoirs and Potentially Promotes HIV Evolution.

Antigen (Ag)-specific immune responses to chronic infections, such as herpes simplex virus type 2 (HSV-2) in HIV/HSV-coinfected persons, may sustain HIV tissue reservoirs by promoting T-cell proliferation but are poorly studied in women on antiretroviral therapy (ART). Mixed anogenital swabs and cervical secretions were self-collected by nine HIV/HSV-2-coinfected women during ART for 28 days to establish subclinical HSV DNA shedding rates and detection of HIV RNA by real-time PCR. Typical herpes lesion site biopsy (TLSB) and cervical biopsy specimens were collected at the end of the daily sampling period. Nucleic acids (NA) isolated from biopsy specimens had HIV quantified and HIV envC2-V5 single-genome amplification (SGA) and T-cell receptor (TCR) repertoires assessed. Women had a median CD4 count of 537 cells/µl (IQR: 483 to 741) at enrollment and HIV plasma viral loads of <40 copies/ml. HSV DNA was detected on 12% of days (IQR: 2 to 25%) from anogenital specimens. Frequent subclinical HSV DNA shedding was associated with increased HIV DNA tissue concentrations and increased divergence from the most recent common ancestor (MRCA), an indicator of HIV replication. Distinct predominant TCR clones were detected in cervical and TLSB specimens in a woman with frequent HSV DNA shedding, with mixing of minor variants between her tissues. In contrast, more limited TCR repertoire mixing was observed in two women with less frequent subclinical HSV DNA shedding. Subclinical HSV shedding in HIV/HSV-coinfected women during ART may sustain HIV tissue reservoirs via Ag exposure or HIV replication. This study provides evidence supporting further study of interventions targeting suppression of Ag-specific immune responses as a component of HIV cure strategies.IMPORTANCE Persons with HIV infection are frequently coinfected with chronic herpesviruses, which periodically replicate and produce viable herpes virions, particularly in anogenital and cervical tissues. Persistent protein expression results in proliferation of CD8+ and CD4+ T cells, and the latter could potentially expand and sustain HIV tissue reservoirs. We found HSV genital shedding rates were positively correlated with HIV DNA concentrations and HIV divergence from ancestral sequences in tissues. Our work suggests that immune responses to common coinfections, such as herpesviruses, may sustain HIV tissue reservoirs during suppressive ART, suggesting future cure strategies should study interventions to suppress replication or reactivation of chronic herpes infections.

Large, Stable, Contemporary Interspecies Recombination Events in Circulating Human Herpes Simplex Viruses.

BACKGROUND: The ubiquitous human pathogens, herpes simplex virus (HSV)-1 and HSV-2, are distinct viral species that diverged approximately 6 million years ago. At least 4 small, ancient HSV-1 × HSV-2 interspecies recombination events have affected the HSV-2 genome, with recombinants and nonrecombinants at each locus circulating today. However, it is unknown whether interspecies recombination can affect other loci and whether new recombinants continue to be generated. METHODS: Using 255 newly sequenced and 230 existing HSV genome sequences, we comprehensively assessed interspecies recombination in HSV. RESULTS: Our findings show that the sizes and locations of interspecies recombination events in HSV-2 are significantly more variable than previously appreciated and that they can impact species-specific T-cell recognition of HSV. CONCLUSIONS: We describe 2 large (>5 kb) recombination events, one of which arose in its current host, demonstrating that interspecies recombination continues to occur today. These results raise concerns about the use of live-attenuated HSV-2 vaccines in high HSV-1 prevalence areas.

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.

Cytomegalovirus shedding from breastmilk and mucosal sites in healthy postpartum women: A pilot study.

Mother-to-child cytomegalovirus (CMV) breastmilk transmission can occur in the postnatal period. In a pilot study, we measured daily CMV detection by polymerase chain reaction in breastmilk, vaginal, and saliva samples from nine healthy CMV-seropositive postpartum women for 28 days. CMV was found in seven of nine women and 171 of 253 breastmilk samples (67.6%). In four women, all breastmilk samples were positive. CMV was less frequently detected in the vagina (39 of 258, 15.1%) and saliva (53 of 258, 20.5%). Daily breastmilk, oral, and genital collection is feasible and demonstrates high variability between women. Further study of the dynamics of CMV in distinct anatomic compartments is warranted.

The Effect of Hormonal Contraception and Menstrual Cycle Timing on Genital Herpes Simplex Virus-2 Shedding and Lesions.

BACKGROUND: The effect of female sex hormones on herpes simplex virus (HSV)-2 shedding and lesion frequency is poorly understood. Previous studies suggest that hormonal contraception may increase the frequency of HSV-2 shedding. METHODS: We studied HSV-2 seropositive women who performed daily genital swabbing for HSV DNA and completed diaries for genital lesions and menses. We used Poisson mixed effects models to determine if HSV detection varied throughout the menstrual cycle, or in response to hormonal contraception. We used the Wilcoxon signed-rank test and rank-sum test to determine if lesion frequency differed by cycle phase or hormonal contraceptive use. RESULTS: In 189 women aged 19 to 46 years who collected swabs on 10,715 days and were not using hormonal contraception, HSV-2 DNA was detected on 20.9% of days in the follicular phase and 17.8% of days in the luteal phase (rate ratio, 1.19; 95% confidence interval, 1.03-1.37, P = 0.02). Genital lesions did not differ in the follicular versus luteal phase (12.8% vs. 10.7%, P = 0.07). In analyses of hormonal contraception, including 244 women, HSV-2 DNA was detected on 19.0% of days for women not using hormonal contraception and 18.3% of days for those using hormonal contraception (P = 0.50). Lesions were present on 11.1% of days for women not using hormonal contraception, and 8.7% of days for those using hormonal contraception (P = 0.66). CONCLUSIONS: In women with genital HSV-2 infection who are not using hormonal contraception, the follicular phase of the cycle may be associated with a higher frequency of HSV-2 shedding compared to the luteal phase. Lesion frequency is similar during the 2 menstrual phases. Hormonal contraception use was not observed to affect genital HSV-2 DNA detection or lesions.

Herpes Simplex Virus Shedding Rate: Surrogate Outcome for Genital Herpes Recurrence Frequency and Lesion Rates, and Phase 2 Clinical Trials End Point for Evaluating Efficacy of Antivirals.

Background: We tested whether genital herpes simplex virus (HSV) shedding is an appropriate surrogate outcome for the clinical outcome of genital herpes lesions in studies of HSV-2 antiviral interventions. Methods: We analyzed prospective data from natural history studies and clinical trials of antiviral agents for HSV-2 in which HSV-2-seropositive participants provided self-collected anogenital swab specimens daily over ≥25 days for HSV DNA quantitation by polymerase chain reaction (PCR). Genital recurrences were self-reported. Results: Among 674 participants, genital HSV shedding was detected on 17% of days, and genital lesions were reported on 10% of days. Within the same session, HSV shedding rates were strongly correlated with lesion rates (ρ = 0.61, P < .0001). The relative reduction in the recurrence rate was 72% (P = .041) for recipients of the antiviral agent pritelivir as compared to recipients of placebo, but it decreased to 21% (P = .75) after adjustment for HSV shedding rate. When evaluating valacyclovir and acyclovir, adjustment for the HSV shedding rate also led to a reduced association of these antivirals with the recurrence rate. Overall, 40%-82% of the antiviral effect on recurrences was explained by its effect on HSV shedding. Conclusion: HSV genital shedding measured by PCR analysis in swab specimens self-collected daily is an appropriate surrogate outcome for genital herpes lesions because it is in the causal pathway to recurrences.

Transient Oral Human Cytomegalovirus Infections Indicate Inefficient Viral Spread from Very Few Initially Infected Cells.

Cytomegalovirus (CMV) is acquired by the oral route in children, and primary infection is associated with abundant mucosal replication, as well as the establishment of latency in myeloid cells that results in lifelong infection. The efficiency of primary CMV infection in humans following oral exposure, however, is unknown. We consistently detected self-limited, low-level oral CMV shedding events, which we termed transient CMV infections, in a prospective birth cohort of 30 highly exposed CMV-uninfected infants. We estimated the likelihood of transient oral CMV infections by comparing their observed frequency to that of established primary infections, characterized by persistent high-level shedding, viremia, and seroconversion. We developed mathematical models of viral dynamics upon initial oral CMV infection and validated them using clinical shedding data. Transient infections comprised 76 to 88% of oral CMV shedding events. For this high percentage of transient infections to occur, we identified two mathematical prerequisites: a very small number of initially infected oral cells (1 to 4) and low viral infectivity (<1.5 new cells infected/cell). These observations indicate that oral CMV infection in infants typically begins with a single virus that spreads inefficiently to neighboring cells. Thus, although the incidence of CMV infection is high during infancy, our data provide a mechanistic framework to explain why multiple CMV exposures are typically required before infection is successfully established. These findings imply that a sufficiently primed immune response could prevent CMV from establishing latent infection in humans and support the achievability of a prophylactic CMV vaccine.IMPORTANCE CMV infects the majority of the world's population and is a major cause of birth defects. Developing a vaccine to prevent CMV infection would be extremely valuable but would be facilitated by a better understanding of how natural human CMV infection is acquired. We studied CMV acquisition in infants and found that infections are usually brief and self-limited and are successfully established relatively rarely. Thus, although most people eventually acquire CMV infection, it usually requires numerous exposures. Our analyses indicate that this is because the virus is surprisingly inefficient, barely replicating well enough to spread to neighboring cells in the mouth. Greater knowledge of why CMV infection usually fails may provide insight into how to prevent it from succeeding.

Prospective cohort study showing persistent HSV-2 shedding in women with genital herpes 2 years after acquisition.

OBJECTIVES: Herpes simplex virus type 2 (HSV-2) is a prevalent infection with great variability in clinical and virological manifestations among individuals. This prospective cohort study aims to evaluate the natural history of HSV-2 reactivation in the genital area in the same group of women over time. METHODS: Eighteen immunocompetent HSV-2 seropositive women were evaluated for viral shedding for 70 consecutive days within a median of 8 months (range 1-24 months) of HSV-2 acquisition and again approximately 2.5 years later from the original study. Participants obtained daily swabs of genital secretions for HSV PCR and recorded genital symptoms. RESULTS: The viral shedding rate was 29% during the initial study and 19% in the follow-up study (32% reduction, P=0.019). Subclinical shedding rate also decreased from 24% to 13% (37% reduction, P=0.032), as did the rate of days with genital lesions from 22% to 15% (33% reduction, P=0.24). The mean copy number during viral shedding remained unchanged over time at 4.8 log10 c/mL (SD=2.0 and 1.6 during each study, respectively, P=0.33). Women with high viral shedding rates in the past were likely to continue to have high shedding rates (r=0.63, P=0.005). CONCLUSIONS: Despite some reduction, high viral shedding rates persist in women with genital HSV-2 greater than 2 years after acquisition.

Valganciclovir for the Suppression of Epstein-Barr Virus Replication.

Epstein-Barr virus (EBV) causes infectious mononucleosis and can lead to lymphoproliferative diseases. We evaluated the effects of valganciclovir on oral EBV shedding in a randomized, double-blind, placebo-controlled study. Twenty-six men received oral valganciclovir or daily placebo for 8 weeks, followed by a 2-week "washout period" and then 8 weeks of the alternative treatment. Valganciclovir reduced the proportion of days with EBV detected from 61.3% to 17.8% (relative risk, 0.28; 95% confidence interval [CI], .21-.41; P < .001), and quantity of virus detected by 0.77 logs (95% CI, .62-.91 logs; P < .001). Further investigations into the impact of valganciclovir on EBV-associated diseases are needed.

Helicase-primase inhibitor pritelivir for HSV-2 infection.

BACKGROUND: Pritelivir, an inhibitor of the viral helicase-primase complex, exhibits antiviral activity in vitro and in animal models of herpes simplex virus (HSV) infection. We tested the efficacy and safety of pritelivir in otherwise healthy persons with genital HSV-2 infection. METHODS: We randomly assigned 156 HSV-2-positive persons with a history of genital herpes to receive one of four doses of oral pritelivir (5, 25, or 75 mg daily, or 400 mg weekly) or placebo for 28 days. Participants obtained daily swabs from the genital area for HSV-2 testing, which was performed with a polymerase-chain-reaction assay. Participants also maintained a diary of genital signs and symptoms. The primary end point was the rate of genital HSV shedding. RESULTS: HSV shedding among placebo recipients was detected on 16.6% of days; shedding among pritelivir recipients was detected on 18.2% of days among those receiving 5 mg daily, 9.3% of days among those receiving 25 mg daily, 2.1% of days among those receiving 75 mg daily, and 5.3% of days among those receiving 400 mg weekly. The relative risk of viral shedding with pritelivir, as compared with placebo, was 1.11 (95% confidence interval [CI], 0.65 to 1.87) with the 5-mg daily dose, 0.57 (95% CI, 0.31 to 1.03) with the 25-mg daily dose, 0.13 (95% CI, 0.04 to 0.38) with the 75-mg daily dose, and 0.32 (95% CI, 0.17 to 0.59) with the 400-mg weekly dose. The percentage of days with genital lesions was also significantly reduced, from 9.0% in the placebo group to 1.2% in both the group receiving 75 mg of pritelivir daily (relative risk, 0.13; 95% CI, 0.02 to 0.70) and the group receiving 400 mg weekly (relative risk, 0.13; 95% CI, 0.03 to 0.52). The rate of adverse events was similar in all groups. CONCLUSIONS: Pritelivir reduced the rates of genital HSV shedding and days with lesions in a dose-dependent manner in otherwise healthy men and women with genital herpes. (Funded by AiCuris; ClinicalTrials.gov number, NCT01047540.).