An escalating dose study to assess the safety, tolerability and immunogenicity of a Herpes Simplex Virus DNA vaccine, COR-1.

This paper describes a single site, open-label Phase I clinical trial evaluating the safety, tolerability and immunogenicity in healthy volunteers of a herpes simplex polynucleotide vaccine that has previously been shown to enhance immunogenicity and protect against lethal herpes simplex virus type 2 (HSV-2) challenge in mice. Five escalating doses of the vaccine, COR-1, were given by intradermal injection to HSV-1 and 2 seronegative healthy individuals. COR-1 was found to be safe and well-tolerated; the only vaccine-related adverse events were mild. While vaccine-induced antibody responses were not detectable, cell-mediated immune responses to HSV-specific peptide groups were identified in 19 of the 20 subjects who completed the study, and local inflammation at the immunisation site was observed. This study indicates COR-1 has potential to be used as a therapeutic vaccine for HSV-2 infection.

HSV antivirals - current and future treatment options.

Herpes simplex virus (HSV) types 1 and 2 can cause infections with clinical manifestations ranging from benign and generally self-limiting blisters or sores as seen in labial and genital herpes through to severe and in rare cases even life-threatening infections. At present, approved treatments for herpes simplex virus are almost all nucleoside analogs. Novel antiviral approaches include therapeutic vaccines, with the most advanced having successfully completed Phase 2 clinical development. Moreover, several small molecules approaches are being developed for the treatment of genital or labial HSV infections. Of particular interest are two novel compounds (amenamevir and pritelivir) belonging to the new class of helicase-primase inhibitors with promising Phase 2 data.

Meta-analysis of pregnancy outcomes in pooled randomized trials on a prophylactic adjuvanted glycoprotein D subunit herpes simplex virus vaccine.

The primary objective of this investigation was to assess whether the AS04-adjuvanted herpes simplex virus (HSV) glycoprotein D candidate prophylactic vaccine against genital herpes disease increases the risk of spontaneous abortion associated with pregnancy conceived within the vaccination exposure window (vaccine dose received within the period starting 60 days before and ending 20 weeks post-conception day). We performed a meta-analysis of studies designed as part of the clinical development program for this vaccine, to examine the relative risk of abortion (spontaneous or elective) associated with unintended vaccination exposure during pregnancy. Nineteen studies, completed before September 2010, were eligible; 5 matched the inclusion criteria for this analysis (presence of a control arm and at least one adverse pregnancy outcome reported). All vaccinated women (N=19,727) were included, of whom 660 reported a pregnancy during the study period. Overall, 13.3% of pregnancies in the HSV vaccine group and 11.0% in the control group resulted in spontaneous abortion; 24.2% and 20.0% resulted in elective abortion. Among 180 women with a first pregnancy conceived in the vaccination exposure window, 16.7% (HSV vaccine) and 9.5% (control) had a spontaneous abortion and 38.5% and 33.3%, elective abortion. The relative risk for spontaneous abortion associated with vaccine exposure during the risk period for abortion in the course of pregnancy was 1.7 (95% CI: 0.7-4.6). For all women receiving HSV vaccine, this relative risk was 1.3 (95% CI: 0.8-2.1). The corresponding relative risks for elective abortion were 1.2 (95% CI: 0.7-2.0) and 1.3 (95% CI: 0.9-1.8). There was no apparent relationship to dosing and no difference between groups in gestational age at the time of spontaneous or elective abortion. In conclusion there is no statistical evidence that the investigational HSV vaccine increased the risk of spontaneous or elective abortion.

Live attenuated herpes simplex virus 2 glycoprotein E deletion mutant as a vaccine candidate defective in neuronal spread.

A herpes simplex virus 2 (HSV-2) glycoprotein E deletion mutant (gE2-del virus) was evaluated as a replication-competent, attenuated live virus vaccine candidate. The gE2-del virus is defective in epithelial cell-to-axon spread and in anterograde transport from the neuron cell body to the axon terminus. In BALB/c and SCID mice, the gE2-del virus caused no death or disease after vaginal, intravascular, or intramuscular inoculation and was 5 orders of magnitude less virulent than wild-type virus when inoculated directly into the brain. No infectious gE2-del virus was recovered from dorsal root ganglia (DRG) after multiple routes of inoculation; however, gE2-del DNA was detected by PCR in lumbosacral DRG at a low copy number in some mice. Importantly, no recurrent vaginal shedding of gE2-del DNA was detected in immunized guinea pigs. Intramuscular immunization outperformed subcutaneous immunization in all parameters evaluated, although individual differences were not significant, and two intramuscular immunizations were more protective than one. Immunized animals had reduced vaginal disease, vaginal titers, DRG infection, recurrent genital lesions, and recurrent vaginal shedding of HSV-2 DNA; however, protection was incomplete. A combined modality immunization using live virus and HSV-2 glycoprotein C and D subunit antigens in guinea pigs did not totally eliminate recurrent lesions or recurrent vaginal shedding of HSV-2 DNA. The gE2-del virus used as an immunotherapeutic vaccine in previously HSV-2-infected guinea pigs greatly reduced the frequency of recurrent genital lesions. Therefore, the gE2-del virus is safe, other than when injected at high titer into the brain, and is efficacious as a prophylactic and immunotherapeutic vaccine.

Efficacy results of a trial of a herpes simplex vaccine.

BACKGROUND: Two previous studies of a herpes simplex virus type 2 (HSV-2) subunit vaccine containing glycoprotein D in HSV-discordant couples revealed 73% and 74% efficacy against genital disease in women who were negative for both HSV type 1 (HSV-1) and HSV-2 antibodies. Efficacy was not observed in men or HSV-1 seropositive women. METHODS: We conducted a randomized, double-blind efficacy field trial involving 8323 women 18 to 30 years of age who were negative for antibodies to HSV-1 and HSV-2. At months 0, 1, and 6, some subjects received the investigational vaccine, consisting of 20 µg of glycoprotein D from HSV-2 with alum and 3-O-deacylated monophosphoryl lipid A as an adjuvant; control subjects received the hepatitis A vaccine, at a dose of 720 enzyme-linked immunosorbent assay (ELISA) units. The primary end point was occurrence of genital herpes disease due to either HSV-1 or HSV-2 from month 2 (1 month after dose 2) through month 20. RESULTS: The HSV vaccine was associated with an increased risk of local reactions as compared with the control vaccine, and it elicited ELISA and neutralizing antibodies to HSV-2. Overall, the vaccine was not efficacious; vaccine efficacy was 20% (95% confidence interval [CI], -29 to 50) against genital herpes disease. However, efficacy against HSV-1 genital disease was 58% (95% CI, 12 to 80). Vaccine efficacy against HSV-1 infection (with or without disease) was 35% (95% CI, 13 to 52), but efficacy against HSV-2 infection was not observed (-8%; 95% CI, -59 to 26). CONCLUSIONS: In a study population that was representative of the general population of HSV-1- and HSV-2-seronegative women, the investigational vaccine was effective in preventing HSV-1 genital disease and infection but not in preventing HSV-2 disease or infection. (Funded by the National Institute of Allergy and Infectious Diseases and GlaxoSmithKline; ClinicalTrials.gov number, NCT00057330.).

Safety and immunogenicity of long HSV-2 peptides complexed with rhHsc70 in HSV-2 seropositive persons.

HSV-2, the primary causative agent of genital herpes, establishes latency in sensory ganglia and reactivates causing recurrent lesions and viral shedding. Induction or expansion of CD4(+) and CD8(+) T cell responses are expected to be important for a successful therapeutic vaccine against HSV-2. A candidate vaccine consisting of 32 synthetic 35mer HSV-2 peptides non-covalently complexed with recombinant human Hsc70 protein (named HerpV, formerly AG-707) was tested for safety and immunogenicity in a Phase I study. These peptides are derived from 22 HSV-2 proteins representative of all phases of viral replication. Thirty-five HSV-2 infected participants were randomized and treated in one of four groups: HerpV+QS-21 (saponin adjuvant), HerpV, QS-21, or vehicle. The vaccine was well tolerated and safe. All seven participants with evaluable samples who were administered HerpV with QS-21 demonstrated a statistically significant CD4(+) T cell response to HSV-2 antigens, and the majority of such participants demonstrated a statistically significant CD8(+) T cell response as well. To our knowledge, this is the first candidate vaccine against HSV-2 to demonstrate a broad CD4(+) and CD8(+) T cell response in HSV-2(+) participants, and the first HSP-based vaccine to show immune responses against viral antigens in humans.

A heat shock protein based polyvalent vaccine targeting HSV-2: CD4(+) and CD8(+) cellular immunity and protective efficacy.

Efforts to develop a subunit vaccine against genital herpes have been hampered by lack of knowledge of the protective antigens of HSV-2, the causative agent of the disease. Vaccines based either on selected antigens or attenuated live virus approaches have not demonstrated meaningful clinical activity. We present here results of a therapeutic vaccine candidate, HerpV (formerly called AG-707), consisting of 32 HSV-2 peptides derived from 22 HSV-2 proteins, complexed non-covalently to the HSP70 chaperone and formulated with QS-21 saponin adjuvant. HerpV is observed to be immunogenic, generating CD4(+) and CD8(+) T cell responses in three mouse strains including HLA-A2 transgenic mice. Optimal T cell stimulation was dependent on the synergistic adjuvant properties of QS-21 with hsp70. The vaccine provided significant protection from viral challenge in a mouse prophylaxis model and showed signals of activity in a guinea pig therapeutic model of existing infection. Peripheral blood mononuclear cells from human HSV-2(+) subjects also showed reactivity in vitro to a subset of individual peptides and to the pool of all 32 peptides. Recombinant human Hsc70 complexed with the 32 peptides also stimulated the expansion of CD8(+) T cells from HSV-2(+) subjects in vitro. These studies demonstrate that HerpV is a promising immunotherapy candidate for genital herpes, and provide a foundation for evaluating HerpV in human HSV-2(+) subjects with the intent of eliciting CD4(+) and CD8(+) T cell responses to a broad array of viral antigens.

[Vitaherpavac is the first Russian herpes simplex virus vaccine obtained on the Vero B continuous cell line].

Vitaherpavac, a dry inactivated herpes simplex virus (HSV) culture vaccine, has been obtained, by using the Vero B continuous cell line as a substrate for accumulation of herpes simplex virus types 1 (US strain) and 2 (VN strain). Vitaherpavac and the similar vaccine Herpovax made by the Research Institute of Vaccines and Sera, Saint Petersburg (for which preparation a primary trypsinized chick embryo cell culture used as a substrate for accumulation of HSV types 1 and 2), underwent comparative clinical trials. The tolerability and therapeutic effectiveness of the vaccine were tested in patients diagnosed as having chronic frequently recurring herpes. The trials have yielded positive results that suggest that it is expedient to introduce of the new vaccine Vitaherpavac into practice to treat chronic recurrent herpetic infection of various localizations. Vitaherpavac has been registered in the Russian Federation and permitted for medical application.

New concepts in herpes simplex virus vaccine development: notes from the battlefield.

The recent discovery that T cells recognize different sets of herpes simplex virus type 1 and type 2 epitopes from seropositive symptomatic and asymptomatic individuals might lead to a fundamental immunologic advance in vaccine development against herpes infection and diseases. The newly introduced needle-free mucosal (i.e., topical ocular and intravaginal) lipopeptide vaccines provide a novel strategy that might target ocular and genital herpes and possibly provide 'heterologous protection' from HIV-1. Indeed, mucosal self-adjuvanting lipopeptide vaccines are easy to manufacture, simple to characterize, extremely pure, cost-effective, highly immunogenic and safe. In this review, we bring together recent published and unpublished data that illuminates the status of epitope-based herpes vaccine development and present an overview of our recent approach to an 'asymptomatic epitope'-based lipopeptide vaccine.

Phase I study of a herpes simplex virus type 2 (HSV-2) DNA vaccine administered to healthy, HSV-2-seronegative adults by a needle-free injection system.

We conducted a double-blind, vehicle-controlled, dose escalation safety and immunogenicity trial of a candidate herpes simplex virus type 2 (HSV-2) surface glycoprotein D2 (gD2) DNA vaccine administered by use of a needle-free device. Sixty-two healthy adults were randomized using a 4:1 vaccine-to-placebo ratio. Half of the participants were HSV-1 seronegative, and all were HSV-2 seronegative. Vaccine doses included 100 microg, 300 microg, 1,000 microg or 3,000 microg of a plasmid expressing the gD2 protein. Subjects received vaccine at 0, 4, 8, and 24 weeks. Some subjects received an additional 1,000-microg boost at 52 weeks. We found that the vaccine was safe and well tolerated, with most adverse events being local site reactions. No dose-limiting toxicities were observed. gD2-specific cytotoxic T-lymphocyte and lymphoproliferation responses were detected 2 weeks after the third vaccine injection in one of four HSV-1-seronegative, HSV-2-seronegative participants who received 3,000 microg of vaccine. A DNA-based vaccination strategy against HSV-2 appears to be safe and may generate a vaccine-specific cellular immune response, but high vaccine doses are likely needed to elicit an immune response in most vaccinees.

A replication-competent, neuronal spread-defective, live attenuated herpes simplex virus type 1 vaccine.

Herpes simplex virus type 1 (HSV-1) produces oral lesions, encephalitis, keratitis, and severe infections in the immunocompromised host. HSV-1 is almost as common as HSV-2 in causing first episodes of genital herpes, a disease that is associated with an increased risk of human immunodeficiency virus acquisition and transmission. No approved vaccines are currently available to protect against HSV-1 or HSV-2 infection. We developed a novel HSV vaccine strategy that uses a replication-competent strain of HSV-1, NS-gEnull, which has a defect in anterograde and retrograde directional spread and cell-to-cell spread. Following scratch inoculation on the mouse flank, NS-gEnull replicated at the site of inoculation without causing disease. Importantly, the vaccine strain was not isolated from dorsal root ganglia (DRG). We used the flank model to challenge vaccinated mice and demonstrated that NS-gEnull was highly protective against wild-type HSV-1. The challenge virus replicated to low titers at the site of inoculation; therefore, the vaccine strain did not provide sterilizing immunity. Nevertheless, challenge by HSV-1 or HSV-2 resulted in less-severe disease at the inoculation site, and vaccinated mice were totally protected against zosteriform disease and death. After HSV-1 challenge, latent virus was recovered by DRG explant cocultures from <10% of vaccinated mice compared with 100% of mock-vaccinated mice. The vaccine provided protection against disease and death after intravaginal challenge and markedly lowered the titers of the challenge virus in the vagina. Therefore, the HSV-1 gEnull strain is an excellent candidate for further vaccine development.

A randomized controlled trial of a replication defective (gH deletion) herpes simplex virus vaccine for the treatment of recurrent genital herpes among immunocompetent subjects.

BACKGROUND: A replication incompetent herpes virus lacking the glycoprotein H gene has been developed as a potential therapeutic vaccine for genital herpes. GOAL: To determine vaccine efficacy on reducing HSV reactivation and clinical disease among immunocompetent persons with recurrent genital HSV-2 infection. STUDY DESIGN: Randomized multicenter placebo-controlled trial. Healthy volunteers who had six or more recurrences of genital herpes per year were randomized to receive injections of vaccine at 0 and 8 or 0, 4, and 8 or 0, 2, 4, and 8 weeks or placebo and were followed for subsequent recurrences for 1 year. RESULTS: The median times to first recurrence of genital herpes (40 days versus 30 days versus 37 days versus 42 days, respectively), mean number of recurrences (3 versus 3 versus 2.4 versus 1.9, respectively), and time to lesion healing of the first recurrence (8 days versus 7.8 days versus 7.4 days versus 7.5 days, respectively), were similar for all treatment groups. Asymptomatic viral shedding was detected by PCR in 61/74 (82%) persons performing daily sample collection following completion of the vaccination series. No differences were noted in the proportion of days with shedding between treatment groups (11.9% versus 17.2% versus 13.1% versus 16.4%, respectively). CONCLUSION: This replication incompetent HSV-2 vaccine lacking the glycoprotein H gene was safe but had no clinical or virologic benefit in the amelioration of genital HSV-2 disease among immunocompetent men and women.

Safety and immunogenicity of glycoprotein D-adjuvant genital herpes vaccine.

BACKGROUND: Two previous trials have suggested that a herpes simplex virus (HSV) type 2 glycoprotein D (gD) vaccine combined with the adjuvants alum and 3'-O-deacylated-monophosphoryl lipid A (MPL) is well tolerated and provides protection against genital herpes disease in women with no preexisting HSV antibody. METHODS: The safety and immunogenicity of this vaccine were evaluated in a large, multicenter, double-blind, randomized, placebo-controlled trial. The effects of sex and preexisting HSV immunity were sought. RESULTS: When solicited symptoms that continued after the initial 4 days of observation were excluded, the incidence of unsolicited symptoms occurring during the 7 months after vaccination (the primary analysis period) was 22.1% in vaccine recipients and 21.9% in placebo recipients. Significant increases in the number of local and systemic symptoms were found in vaccine recipients within 4 days after vaccination. However, most symptoms were mild to moderate in severity and were short lived. Women reported symptoms more frequently than did men, but preexisting immunity had little effect. The vaccine induced higher titers of HSV gD antibody on enzyme-linked immunosorbent assays than did natural infection with HSV. CONCLUSION: The vaccine was generally safe, well tolerated, and immunogenic.

Herpes simplex virus type 2 vaccines: new ground for optimism?

The development of effective prophylactic and therapeutic vaccines against genital herpes has proven problematic. Difficulties are associated with the complexity of the virus life cycle (latency) and our relatively poor understanding of the mechanism of immune control of primary and recurrent disease. The types of effector cells and the mechanisms responsible for their activation and regulation are particularly important. Studies from my and other laboratories have shown that recurrent disease is prevented by virus-specific T helper 1 (Th1) cytokines (viz., gamma interferon) and activated innate immunity. Th2 cytokines (viz., interleukin-10 [IL-10]) and regulatory (suppressor) T cells downregulate this immune profile, thereby allowing unimpeded replication of reactivated virus and recurrent disease. Accordingly, an effective therapeutic vaccine must induce Th1 immunity and be defective in Th2 cytokine production, at least IL-10. These concepts are consistent with the findings of the most recent clinical trials, which indicate that (i) a herpes simplex virus type 2 (HSV-2) glycoprotein D (gD-2) vaccine formulated with a Th1-inducing adjuvant has prophylactic activity in HSV-2- and HSV-1-seronegative females, an activity attributed to the adjuvant function, and (ii) a growth-defective HSV-2 mutant (ICP10DeltaPK), which is deleted in the Th2-polarizing gene ICP10PK, induces Th1 immunity and has therapeutic activity in both genders. The ICP10DeltaPK vaccine prevents recurrent disease in 44% of treated subjects and reduces the frequency and severity of recurrences in the subjects that are not fully protected. Additional studies to evaluate these vaccines are warranted.

T cell immunity to herpes simplex viruses in seronegative subjects: silent infection or acquired immunity?

During the course of investigating T cell responses to HSV among volunteers entering trials of investigational genital herpes vaccines, 6 of the 24 immunocompetent subjects with no prior history of oral/labial or genital herpes possessed HSV-specific T cell immunity but, by multiple determinants of even the most sensitive serological assays, remained seronegative to HSV-1 and -2. Of these six immune seronegative (IS; HSV-seronegative with HSV-specific T cell responses) subjects, two had transient HSV-specific T cell responses, while four had CD4(+) and CD8(+) T cell responses directed at HSV that persisted for up to 4 years. CD4(+) T cell clones were isolated that recognized and had high binding affinities to epitopes in HSV-2 tegument proteins. All six IS subjects had potential sexual exposure to an HSV-2-infected sexual partner. Oral and genital mucosal secretions were sampled and tested for the presence of infectious HSV and HSV DNA. No evidence of HSV was detected in >1500 samples obtained from these IS subjects. The identification of persistent T cell responses to HSV in seronegative subjects is a novel finding in the herpesvirus field and suggests either undetected infection or acquired immunity in the absence of infection. Understanding the basis of these acquired immune responses may be critical in developing effective vaccines for genital herpes.

Glycoprotein-D-adjuvant vaccine to prevent genital herpes.

BACKGROUND: An effective prophylactic vaccine would help control the spread of genital herpes. METHODS: We conducted two double-blind, randomized trials of a herpes simplex virus type 2 (HSV-2) glycoprotein-D-subunit vaccine with alum and 3-O-deacylated-monophosphoryl lipid A in subjects whose regular sexual partners had a history of genital herpes. In Study 1, subjects were seronegative for herpes simplex virus type 1 (HSV-1) and HSV-2; in Study 2, subjects were of any HSV serologic status. At months 0, 1, and 6, subjects received either vaccine or a control injection and were evaluated for 19 months. The primary end point was the occurrence of genital herpes disease in all subjects in Study 1 and in HSV-2-seronegative female subjects in Study 2. RESULTS: A total of 847 subjects who were seronegative for both HSV-1 and HSV-2 (268 of them women, in Study 1) and 1867 subjects who were seronegative for HSV-2 (710 of them women, in Study 2) underwent randomization and received injections. Vaccination was well tolerated and elicited humoral and cellular responses. Overall, the efficacy of the vaccine was 38 percent in Study 1 (95 percent confidence interval, -18 to 68 percent; 15 cases occurred in the vaccine group and 24 in the control group), and efficacy in female subjects was 42 percent in Study 2 (95 percent confidence interval, -31 to 74 percent; 9 cases occurred in the vaccine group and 16 in the control group). In both studies, further analysis showed that the vaccine was efficacious in women who were seronegative for both HSV-1 and HSV-2: efficacy in Study 1 was 73 percent (95 percent confidence interval, 19 to 91 percent; P=0.01), and efficacy in Study 2 was 74 percent (95 percent confidence interval, 9 to 93 percent; P=0.02). It was not efficacious in women who were seropositive for HSV-1 and seronegative for HSV-2 at base line or in men. CONCLUSIONS: These studies suggest that the glycoprotein D vaccine has efficacy against genital herpes in women who are seronegative for both HSV-1 and HSV-2 at base line but not in those who are seropositive for HSV-1 and seronegative for HSV-2. It had no efficacy in men, regardless of their HSV serologic status.