Herpes simplex virus type 2 suppressive therapy with acyclovir or valacyclovir does not select for specific HIV-1 resistance in HIV-1/HSV-2 dually infected persons

Herpes Simplex Virus: The Interplay Between HSV, Host, and HIV-1

Herpes simplex virus proteins interact with host (human) proteins and create an environment conducive for its replication. Genital ulceration due to herpes simplex virus type 2 (HSV-2) infections is an important clinical manifestation reported to increase the risk of human immunodeficiency virus type 1 (HIV-1) acquisition and replication in HIV-1/HSV-2 coinfection. Dampening the innate and adaptive immune responses of the skin-resident dendritic cells, HSV-2 not only helps itself, but creates a "yellow brick road" for one of the most dreaded viruses HIV, which is transmitted mainly through the sexual route. Although, data from clinical trials show that HSV-2 suppression reduces HIV-1 viral load, there are hardly any reports presenting conclusive evidence on the impact of HSV-2 coinfection on HIV-1 disease progression. Be that as it may, understanding the interplay between these three characters (HSV, host, and HIV-1) is imperative. This review endeavors to collate studies on the influence of HSV-derived proteins on the host response and HIV-1 replication. Studying such complex interactions may help in designing and developing common strategies for the two viruses to keep these "partners in crime" at bay.

Herpes simplex virus type 2 (HSV-2) genital shedding in HSV-2-/HIV-1-co-infected women receiving effective combination antiretroviral therapy

The dynamics of genital shedding of HSV-2 DNA was assessed in HIV-1-infected women taking combination antiretroviral therapy (cART). HIV-1 RNA, HIV-1 DNA and HSV DNA loads were measured during 12-18 months using frozen plasma, PBMC and cervicovaginal lavage samples from 22 HIV-1-infected women, including 17 women naive for antiretroviral therapy initiating cART and 5 women with virological failure switching to a new regimen. Nineteen (86%) women were HSV-2-seropositive. Among HSV-2-/HIV-1-co-infected women, HIV-1 RNA loads showed a rapid fall from baseline after one month of cART, in parallel in paired plasma and cervicovaginal secretions. In contrast, HIV-1 DNA loads did not show significant variations from baseline up to 18 months of treatment in both systemic and genital compartments. HSV DNA was detected at least once in 12 (63%) of 19 women during follow up: HSV-2 shedding in the genital compartment was observed in 11% of cervicovaginal samples at baseline and in 16% after initiating or switching cART. Cervicovaginal HIV-1 RNA loads were strongly associated with plasma HIV-1 RNA loads over time, but not with cervicovaginal HSV DNA loads. Reactivation of genital HSV-2 replication frequently occurred despite effective cART in HSV-2-/HIV-1-co-infected women. Genital HSV-2 replication under cART does not influence cervicovaginal HIV-1 RNA or DNA shedding.

Valacyclovir Decreases Plasma HIV-1 RNA in HSV-2 Seronegative Individuals: A Randomized Placebo-Controlled Crossover Trial

BACKGROUND

Acyclovir (ACV), a highly specific anti-herpetic drug, acts as a DNA chain terminator for several human herpesviruses (HHVs), including HHV-2 (HSV-2), a common human immunodeficiency virus (HIV)-1 co-pathogen. Several trials demonstrated that HSV-2 suppressive therapy using ACV or its prodrug valacyclovir (valACV) reduced plasma HIV-1 viral load (VL) in HIV-1/HSV-2 coinfected persons, and this was proposed to be due to a decrease in generalized immune activation. Recently, however, we found that ACV directly suppresses HIV-1 ex vivo in tissues free of HSV-2 but endogenously coinfected with other HHVs. Here, we asked whether valACV suppresses VL in HIV-1 infected HSV-2-seronegative persons.

METHODS

Eighteen HIV-1 infected HSV-2-seronegative individuals were randomly assigned in a double blind placebo-controlled, crossover trial. Eligible participants had CD4 cell counts of ≥500 cells/µL and were not taking antiretroviral therapy. Subjects in group A received 12 weeks of valACV 500 mg given twice daily by mouth followed by 2 weeks of a no treatment washout and then 12 weeks of placebo; subjects in group B received 12 weeks of placebo followed by 2 weeks of no treatment washout and then 12 weeks of valACV 500 mg twice daily.

RESULTS

HIV-1 VL in plasma of patients treated with valACV 500 mg twice daily for 12 weeks was reduced on average by 0.37 log10 copies/mL.

CONCLUSIONS

These data indicate that the effects of valACV on HIV-1 replication are not related to the suppression of HSV-2-mediated inflammation and are consistent with a direct effect of ACV on HIV-1 replication.

Impact of CMV therapy with valganciclovir on immune activation and the HIV viral load in semen and blood: an observational clinical study

BACKGROUND

The HIV RNA viral load (VL) in vaginal secretions and semen is an independent predictor of HIV transmission. Blood VL is associated with semen VL, and local mucosal factors, such as semen cytomegalovirus (CMV) reactivation, may play an important role.

METHODS

Twenty-one HIV-CMV-coinfected, antiretroviral-naive men received 900 mg of oral valganciclovir once daily for 2 weeks in an open-label study. Blood and semen were collected at baseline, after 2 weeks of valganciclovir, and 2 months after therapy completion. The primary end point was change in semen HIV levels at 2 weeks, and the secondary end points were change in semen HIV VL at 2 months and change in semen CMV levels.

RESULTS

The HIV VLs fell significantly at 2 weeks in semen (median 3.44-3.02 log10 copies/mL, P = 0.02) and blood (median 3.61-3.10 log10 copies/mL, P < 0.01) and returned to baseline after therapy completion (median 3.24 and 3.71 log10 copies/mL in semen and blood, respectively). Semen CMV levels also fell on treatment (median 2.13-1.62 log10 copies/mL, P < 0.01) and continued to fall after therapy completion (median 0.91 log10 copies/mL at week 8, P < 0.001 vs. baseline). The reduced semen CMV VL was associated with decreased semen T-cell activation and enhanced CMV-specific T-cell responses in blood; changes in the semen HIV VL were not associated with immune parameters.

CONCLUSIONS

Although valganciclovir therapy was associated with reduced HIV and semen CMV levels, these results suggest that the reduced HIV VL was a direct drug effect rather than a CMV antiviral effect or CMV-associated immune alterations.

Herpes simplex virus type 2 and HIV disease progression: a systematic review of observational studies

Background

Herpes simplex virus type 2 (HSV-2) is a common co-infection among HIV-infected adults that is hypothesized to accelerate HIV disease progression.

Methods

We searched Medline, EMBASE, relevant conference proceedings (2006–12) and bibliographies of identified studies without language restriction for cohort studies examining the impact of HSV-2 on highly active antiretroviral therapy-untreated HIV disease in adults. The exposure of interest was HSV-2 seropositivity or clinical/laboratory markers of HSV-2 activity. The primary outcome was HIV disease progression, defined as antiretroviral initiation, development of AIDS/opportunistic infection, or progression to CD4 count thresholds (≤200 or ≤350 cells/mm³). Secondary outcomes included HIV plasma viral load and CD4 count.

Results

Seven studies were included. No definitive relationship was observed between HSV-2 seropositivity and time to antiretroviral initiation (n=2 studies), CD4≤350 (n=1), CD4≤200 (n=1), death (n=1), viral load (n=6) or CD4 count (n=3). Although two studies each observed trends towards accelerated progression to clinical AIDS/opportunistic infection in HSV-2 seropositives, with pooled unadjusted hazard ratio=1.85 (95% CI=1.12,3.06; I²=2%), most OIs observed in the study for which data were available can occur at high CD4 counts and may not represent HIV progression. In contrast, a single study HSV-2 disease activity found that the presence of genital HSV-2 DNA was associated with a 0.4 log copies/mL increase in HIV viral load.

Conclusions

Despite an observation that HSV-2 activity is associated with increased HIV viral load, definitive evidence linking HSV-2 seropositivity to accelerated HIV disease progression is lacking. The attenuating effects of acyclovir on HIV disease progression observed in recent trials may result both from direct anti-HIV activity as well as from indirect benefits of HSV-2 suppression.

High-dose valacyclovir decreases plasma HIV-1 RNA more than standard-dose acyclovir in persons coinfected with HIV-1 and HSV-2: a randomized crossover trial

BACKGROUND

Standard doses of herpes simplex virus (HSV) suppressive therapy reduce plasma HIV-1 RNA levels (0.25-0.53 log10 copies per milliliter) among HIV-1/HSV-2 coinfected persons. Postulated mechanisms for this effect include direct inhibition of HIV-1 by acyclovir or indirect reduction by decreasing HSV-associated inflammation. We hypothesized that high-dose valacyclovir would further reduce plasma HIV-1 RNA and that the effect would be mediated by greater suppression of HSV shedding.

METHODS

Thirty-four participants with HIV-1 and HSV-2 not on antiretroviral therapy were enrolled into a randomized, open-label crossover trial of valacyclovir 1000 mg twice daily or acyclovir 400 mg twice daily for 12 weeks, followed by a 2-week washout, and then the alternate treatment arm for 12 weeks. HSV DNA was measured from daily self-collected genital swabs for the initial 4 weeks of each arm, and HIV-1 RNA was quantified from weekly plasma samples.

RESULTS

Twenty-eight participants provided plasma samples and genital swabs on both acyclovir and valacyclovir. The genital HSV-2 shedding rate was the same on valacyclovir and acyclovir [7.8% vs. 8.2% of days; relative risk: 0.95; 95% confidence interval (CI): 0.66 to 1.37; P = 0.78]. Plasma HIV-1 RNA was 0.27 log10 copies per milliliter lower on valacyclovir compared with acyclovir (95% CI: -0.41 to -0.14 log10 copies per milliliter; P < 0.001); this was unchanged after adjustment for genital HSV-2 shedding.

CONCLUSIONS

High-dose valacyclovir reduces plasma HIV-1 RNA levels more than standard-dose acyclovir in HIV-1/HSV-2-seropositive persons not receiving antiretroviral therapy. The incremental reduction in plasma HIV-1 RNA achieved is not mediated by greater genital HSV-2 suppression.

Partner characteristics predicting HIV-1 set point in sexually acquired HIV-1 among African seroconverters

Plasma HIV-1 RNA set point is an important predictor of HIV-1 disease progression. We hypothesized that inoculum size and HIV-1 exposure prior to HIV-1 transmission may modulate set point. We evaluated predictors of set point among 141 African HIV-1 seroconverters and their HIV-1-infected study partners. We compared characteristics of seroconverters and their HIV-1-infected partners and HIV-1 set point. Data were from a clinical trial of genital HSV-2 suppression with acyclovir to reduce HIV-1 transmission in HIV-1 serodiscordant couples with HIV-1 transmission linkage assigned through virus sequencing. Our analysis includes data from all transmissions including those with transmission linkage to the HIV-1-infected "source partner" and those that were not linked to their HIV-1-infected study partner. In multivariable analysis, higher plasma HIV-1 in source partners was associated with higher seroconverter set point ( + 0.44 log10 copies/ml per log(10) source partner plasma HIV-1, p < 0.001). In addition, bacterial vaginosis (BV) among female source partners near the time of infection was associated with higher set point in their male seroconverters ( + 0.49 log(10), p = 0.04). Source partner characteristics associated with lower set point included male circumcision ( - 0.63 log(10), p = 0.03) and assignment to acyclovir ( - 0.44 log10, p = 0.02). The proportion of variation in set point explained by plasma HIV-1 RNA of the source partner, after controlling for other factors, was 0.06. Source partner plasma HIV-1 level is the most significant predictor of seroconverter set point, possibly reflecting characteristics of the transmitted virus. Acyclovir use, BV among women source partners, and circumcision among male source partners may alter the set point by affecting transmitted virus inoculum in the source partners' genital compartment.

Short communication: T cell activation in HIV-1/herpes simplex virus-2-coinfected Kenyan women receiving valacyclovir

Herpes simplex virus-2 (HSV-2) suppression with acyclovir or valacyclovir reduces HIV-1 viral RNA levels; one hypothesis is that HSV-2 suppression reduces immune activation. We measured T cell immune activation markers among women participating in a randomized placebo-controlled trial of valacyclovir to reduce HIV-1 RNA levels among pregnant women. Although valacyclovir was associated with lower HIV-1 RNA levels, the distribution of both CD4(+) and CD8(+) CD38(+)HLA-DR(+) T cells was not different among women taking valacyclovir when compared to women taking placebo. Further study is needed to understand the mechanism of HIV-1 RNA reduction following herpes suppression among those coinfected with HIV-1 and HSV-2.

Effects of valacyclovir on markers of disease progression in postpartum women co-infected with HIV-1 and herpes simplex virus-2

Objective

Herpes simplex virus type 2 (HSV-2) suppression has been shown to reduce HIV-1 disease progression in non-pregnant women and men, but effects on pregnant and postpartum women have not been described.

Methods

We analyzed data from a cohort of Kenyan women participating in a randomized clinical trial of HSV-2 suppression. Pregnant HIV-1-seropositive, HSV-2-seropositive women who were not eligible for antiretroviral therapy (WHO stage 1–2, CD4>250 cells/µl) were randomized to either 500 mg valacyclovir or placebo twice daily from 34 weeks gestation through 12 months postpartum. Women received zidovudine and single-dose nevirapine for prevention of mother-to-child HIV-1 transmission. HIV-1 progression markers, including CD4 count and plasma HIV-1 RNA levels, were measured serially. Multivariate linear regression was used to compare progression markers between study arms.

Results

Of 148 women randomized, 136 (92%) completed 12 months of postpartum follow-up. While adjusted mean CD4 count at 12 months (565 cells/µl placebo arm, 638 cells/µl valacyclovir arm) increased from antenatal levels in both arms, the mean CD4 count increase was 73 cells/µl higher in the valacyclovir arm than placebo arm (p = 0.03). Mean increase in CD4 count was 154 cells/µl in the valacyclovir arm, almost double the increase of 78 cells/µl in the placebo arm. At 12 months, adjusted HIV-1 RNA levels in the placebo arm increased by 0.66 log₁₀ copies/ml from baseline, and increased by only 0.21 log₁₀ copies/ml in the valacyclovir arm (0.40 log₁₀ copies/ml difference, p = 0.001).

Conclusion

Women randomized to valacyclovir suppressive therapy during pregnancy and postpartum had greater increases in CD4 counts and smaller increases in plasma HIV-1 RNA levels than women in the placebo arm. Valacyclovir suppression during pregnancy and breastfeeding may improve outcomes and delay antiretroviral therapy for HIV-1/HSV-2 co-infected women.

Effect of daily aciclovir on HIV disease progression in individuals in Rakai, Uganda, co-infected with HIV-1 and herpes simplex virus type 2: a randomised, double-blind placebo-controlled trial

BACKGROUND

Daily suppression of herpes simplex virus type 2 (HSV-2) reduces plasma HIV-1 concentrations and modestly delayed HIV-1 disease progression in one clinical trial. We investigated the effect of daily suppressive aciclovir on HIV-1 disease progression in Rakai, Uganda.

METHODS

We did a single site, parallel, randomised, controlled trial of HIV-1, HSV-2 dually infected adults with CD4 cell counts of 300-400 cells per μL. We excluded individuals who had an AIDS-defining illness or active genital ulcer disease, and those that were taking antiretroviral therapy. Participants were randomly assigned (1:1) with computer-generated random numbers in blocks of four to receive either aciclovir 400 mg orally twice daily or placebo; participants were followed up for 24 months. All study staff and participants were masked to treatment, except for the two statisticians. The primary outcome was CD4 cell count less than 250 cells per μL or initiation of antiretroviral therapy for WHO stage 4 disease. Our intention-to-treat analysis used Cox proportional hazards models, adjusting for baseline log(10) viral load, CD4 cell count, sex, and age to assess the risk of disease progression. We also investigated the effect of suppressive HSV-2 treatment stratified by baseline HIV viral load with a Cox proportional hazards model. This trial is registered with ClinicalTrials.gov, number NCT00405821.

FINDINGS

440 participants were randomly assigned, 220 to each group. 110 participants in the placebo group and 95 participants in the treatment group reached the primary endpoint (adjusted hazard ratio [HR] 0·75, 95% CI 0·58-0·99; p=0·040). 24 participants in the placebo group and 22 in the treatment group were censored, but all contributed data for the final analysis. In a subanalysis stratified by baseline HIV viral load, participants with a baseline viral load of 50,000 copies mL or more in the treatment group had a reduced HIV disease progression compared with those in the placebo group (0·62, 0·43-0·96; p=0·03). No significant difference in HIV disease progression existed between participants in the treatment group and those in the placebo group who had baseline HIV viral loads of less than 50,000 copies per mL (0·90, 0·54-1·5; p=0·688). No safety issues related to aciclovir treatment were identified.

INTERPRETATION

Aciclovir reduces the rate of disease progression, with the greatest effect in individuals with a high baseline viral load. Suppressive aciclovir might be warranted for individuals dually infected with HSV-2 and HIV-1 with viral loads of 50,000 copies per mL or more before initiation of antiretroviral treatment.

FUNDING

National Institute of Allergy and Infectious Diseases, National Cancer Institute (National Institutes of Health, USA).

Infectious co-factors in HIV-1 transmission herpes simplex virus type-2 and HIV-1: new insights and interventions

Over the last thirty years, epidemiologic and molecular studies indicate a strong and synergist relationship between the dual epidemics of herpes simplex type 2 (HSV-2) and HIV-1 infection. While prospective studies show that HSV-2 infection increases the risk for HIV-1 acquisition by 2- to 3-fold, HSV-2 suppression with standard prophylactic doses of HSV-2 therapy did not prevent HIV-1 acquisition. Reconciling these discrepancies requires understanding recent HSV-2 pathogenesis research, which indicates HSV-2 infection is not a latent infection with infrequent recurrence but a near constant state of reactivation and viral shedding which is not completely suppressed by standard antivirals. Because current antivirals do not prevent or fully suppress HSV-2 replication, priorities are HSV-2 vaccine development and antivirals that reach high concentrations in the genital mucosa and suppress the persistent genital inflammation associated with genital herpes reactivation in order to reduce the increased susceptibility to HIV-1 infection associated with HSV-2. HIV-1 and HSV-2 synergy is also seen among co-infected individuals who exhibit higher HIV-1 viral load compared to HSV-2 uninfected individuals. Standard HSV-2 therapy modestly lowers HIV-1 viral load and is associated with slower HIV-1 disease progression. A promising area of research is higher doses of HSV-2 suppressive therapy achieving a greater reduction in plasma HIV-1 RNA, which could translate to greater reductions in HIV-1 disease progression and infectiousness. However, many questions remain to be answered including potential effectiveness and cost-effectiveness of higher dose HSV-2 suppressive therapy. Mathematical models of HSV-2 and HIV-1 at a population level would be useful tools to estimate the potential impact and cost-effectiveness of higher dose HSV-2 suppressive therapy.

Exploiting the anti-HIV-1 activity of acyclovir: suppression of primary and drug-resistant HIV isolates and potentiation of the activity by ribavirin

Multiple clinical trials have demonstrated that herpes simplex virus 2 (HSV-2) suppressive therapy using acyclovir (ACV) or valacyclovir in HIV-1/HSV-2-infected persons increased the patient's survival and decreased the HIV-1 load. It has been shown that the incorporation of ACV-monophosphate into the nascent DNA chain instead of dGMP results in the termination of viral DNA elongation and directly inhibits laboratory strains of HIV-1. We evaluated here the anti-HIV activity of ACV against primary HIV-1 isolates of different clades and coreceptor specificity and against viral isolates resistant to currently used drugs, including zidovudine, lamivudine, nevirapine, a combination of nucleoside reverse transcriptase inhibitors (NRTIs), a fusion inhibitor, and two protease inhibitors. We found that, at clinically relevant concentrations, ACV inhibits the replication of these isolates in human tissues infected ex vivo. Moreover, addition of ribavirin, an antiviral capable of depleting the pool of intracellular dGTP, potentiated the ACV-mediated HIV-1 suppression. These data warrant further clinical investigations of the benefits of using inexpensive and safe ACV alone or in combination with other drugs against HIV-1, especially to complement or delay highly active antiretroviral therapy (HAART) initiation in low-resource settings.

Valacyclovir suppressive therapy reduces plasma and breast milk HIV-1 RNA levels during pregnancy and postpartum: a randomized trial

BACKGROUND

The effect of herpes simplex virus type 2 (HSV-2) suppression on human immunodeficiency virus type 1 (HIV-1) RNA in the context of prevention of mother-to-child transmission (PMTCT) interventions is unknown.

METHODS

Between April 2008 and August 2010, we conducted a randomized, double-blind trial of twice daily 500 mg valacyclovir or placebo beginning at 34 weeks gestation in 148 HIV-1/HSV-2 coinfected pregnant Kenyan women ineligible for highly active antiretroviral therapy (CD4 > 250 cells/mm(3)). Women received zidovudine and single dose nevirapine for PMTCT and were followed until 12 months postpartum.

RESULTS

Mean baseline plasma HIV-1 RNA was 3.88 log(10) copies/mL. Mean plasma HIV-1 was lower during pregnancy (-.56 log(10) copies/mL; 95% confidence interval [CI], -.77 to -.34) and after 6 weeks postpartum (-.51 log(10) copies/mL; 95% CI, -.73 to -.30) in the valacyclovir arm than the placebo arm. Valacyclovir reduced breast milk HIV-1 RNA detection at 6 and 14 weeks postpartum compared with placebo (30% lower, P = .04; 46% lower, P = .01, respectively), but not after 14 weeks. Cervical HIV-1 RNA detection was similar between arms (P = .91).

CONCLUSIONS

Valacyclovir significantly decreased early breast milk and plasma HIV-1 RNA among women receiving PMTCT.

CLINICAL TRIALS REGISTRATION

NCT00530777.

High-dose valacyclovir HSV-2 suppression results in greater reduction in plasma HIV-1 levels compared with standard dose acyclovir among HIV-1/HSV-2 coinfected persons: a randomized, crossover trial

BACKGROUND

Standard-dose HSV-2 suppressive therapy (acyclovir 400 mg twice daily) reduces plasma HIV-1 levels by 0.25-0.50 log(10) copies/mL. It is not known if higher doses might further suppress HIV-1 levels.

METHODS

We enrolled 32 HIV-1/HSV-2 dually infected Kenyan individuals who were not on antiretroviral therapy (ART) into a randomized, crossover trial of 2 dosing regimens of HSV-2 suppression: valacyclovir 1.5 g vs acyclovir 400 mg, both twice daily for 12 weeks, then a 2-week washout, and then the alternative for 12 weeks. Weekly plasma HIV-1 RNA quantity was measured (ClinicalTrials.gov number NCT01026454).

RESULTS

Mean plasma HIV-1 levels were significantly lower on valacyclovir compared with acyclovir: 2.94 vs 3.56 log(10) copies/mL, an average difference of 0.62 log(10) copies/mL (95% confidence interval [CI]: -0.68, -0.55; P < .001), a 76% decrease. Valacyclovir resulted in a 1.23 log(10) copies/mL decrease compared with baseline HIV-1 levels without HSV-2 suppression. Adherence was similar (99.4% of dispensed study tablets taken), and high-dose valacyclovir was well tolerated.

CONCLUSIONS

High-dose valacyclovir reduced plasma HIV-1 viral levels by 0.62 log(10) copies/mL compared with standard-dose acyclovir. The potential for higher-dose HSV-2 suppressive therapy to slow HIV-1 disease progression and reduce HIV-1 infectiousness among HIV-1/HSV-2 coinfected persons not yet eligible for ART warrants further evaluation.