Attenuated Varicella-zoster Virus Vaccine Research Articles

Upregulation of keratin 15 is required for varicella-zoster virus replication in keratinocytes and is attenuated in the live attenuated vOka vaccine strain

Varicella-zoster virus (VZV) is the etiological agent of chickenpox and shingles, diseases characterised by epidermal virus replication in skin and mucosa and the formation of blisters. We have previously shown that VZV infection has a profound effect on keratinocyte differentiation, altering the normal pattern of epidermal gene expression. In particular, VZV infection reduces expression of suprabasal keratins 1 and 10 and desmosomal proteins, disrupting epidermal structure to promote expression of a blistering phenotype. Here, we extend these findings to show that VZV infection upregulates the expression of keratin 15 (KRT15), a marker expressed by basal epidermal keratinocytes and hair follicles stem cells. We demonstrate that KRT15 is essential for VZV replication in the skin, since downregulation of KRT15 inhibits VZV replication in keratinocytes, while KRT15 exogenous overexpression supports viral replication. Importantly, our data show that VZV upregulation of KRT15 depends on the expression of the VZV immediate early gene ORF62. ORF62 is the only regulatory gene that is mutated in the live attenuated VZV vaccine and contains four of the five fixed mutations present in the VZV Oka vaccine. Our data indicate that the mutated vaccine ORF62 is not capable of upregulating KRT15, suggesting that this may contribute to the vaccine attenuation in skin. Taken together our data present a novel association between VZV and KRT15, which may open a new therapeutic window for a topical targeting of VZV replication in the skin via modulation of KRT15.

Investigation of the safety of live attenuated varicella-zoster virus vaccination in patients with relapse-remitting multiple sclerosis treated with natalizumab: A case series and review of the literature.

It is generally recommended to avoid live attenuated vaccines in patients treated with high efficacy disease-modifying treatment (DMT). However, a delay in starting DMT in highly active or aggressive multiple sclerosis (MS) might lead to a significant disability. We aimed to report a case series of 16 highly active RRMS patients who received the live-attenuated varicella-zoster virus (VZV) vaccine during treatment with natalizumab. This retrospective case series was conducted between September 2015 and February 2022 at the MS Research Center of Sina and Qaem hospital, Tehran, Mashhad, Iran, to identify the outcome of highly active MS patients who received the live-attenuated VZV vaccine on natalizumab. Two males and 14 females were included in this study, with a mean age of 25.5±8.4-year-old. 10 patients were naïve cases of highly active MS, and six were escalated to natalizumab. The patients received two doses of live attenuated VZV vaccine after a mean of 6.72 cycles of natalizumab treatment. Except for the one who experienced mild chickenpox infection, no serious adverse event or disease activity was evident after vaccination. While our data do not confirm the safety of the live attenuated VZV vaccine in natalizumab recipients, it highlights the importance of case-by-case decision-making in MS management based on the risk-benefit assessment.

Herpes zoster: A Review of Clinical Manifestations and Management.

The Varicella-zoster virus (VZV) or human herpes virus 3 is a neurotropic human alpha herpes virus responsible for chickenpox/varicella and shingles/Herpes zoster (HZ). This review will focus on HZ. Since HZ is secondary to varicella, its incidence increases with age. In children and youngsters, HZ is rare and associated to metabolic and neoplastic disorders. In adults, advanced age, distress, other infections (such as AIDS or COVID-19), and immunosuppression are the most common risk factors. HZ reactivation has recently been observed after COVID-19 vaccination. The disease shows different clinical stages of variable clinical manifestations. Some of the manifestations bear a higher risk of complications. Among the possible complications, postherpetic neuralgia, a chronic pain disease, is one of the most frequent. HZ vasculitis is associated with morbidity and mortality. Renal and gastrointestinal complications have been reported. The cornerstone of treatment is early intervention with acyclovir or brivudine. Second-line treatments are available. Pain management is essential. For (secondary) prophylaxis, currently two HZV vaccines are available for healthy older adults, a live attenuated VZV vaccine and a recombinant adjuvanted VZV glycoprotein E subunit vaccine. The latter allows vaccination also in severely immunosuppressed patients. This review focuses on manifestations of HZ and its management. Although several articles have been published on HZ, the literature continues to evolve, especially in regard to patients with comorbidities and immunocompromised patients. VZV reactivation has also emerged as an important point of discussion during the COVID-19 pandemic, especially after vaccination. The objective of this review is to discuss current updates related to clinical presentations, complications, and management of HZ.

Herpes Zoster and Its Prevention by Vaccination.

Herpes zoster (HZ; shingles) results from reactivation of varicella-zoster virus (VZV) after primary infection as varicella (chicken pox). It affects mainly older adults and people with immunocompromising diseases or treatments. The most common complication is postherpetic neuralgia (PHN), which has significant adverse effects on quality of life and activities of daily living. Since PHN cannot be prevented once HZ has occurred, and treatment is only modestly successful and is associated with significant side effects, the recent introduction of an effective vaccine is an important achievement. This new vaccine, which combines a single VZV glycoprotein (gE) and a multicomponent adjuvant, is superior to the previously available live attenuated VZV vaccine. The recombinant adjuvanted vaccine is remarkably effective in restoring the protective T cell-mediated immunity required to prevent HZ. Its clinical efficacy is much greater than that observed with other vaccines for older individuals affected by immune senescence, and its safety profile is very acceptable. It has been recommended in the USA and Canada for people who are 50 years of age and older. The immunogenicity and safety of this vaccine in severely immunocompromised individuals, such as after chemotherapy for malignancy, after solid organ or stem cell transplant, and in people with HIV are being studied.

Efficient induction of cell-mediated immunity to varicella-zoster virus glycoprotein E co-lyophilized with a cationic liposome-based adjuvant in mice

Varicella zoster virus (VZV) is a neurotropic and lymphotropic alpha herpesvirus that causes varicella and herpes zoster (HZ). At a primary infection, VZV causes varicella in young children. Reactivation of latent VZV in sensory ganglia causes painful HZ in elderly people, occasionally leading to a serious complication, postherpetic neuralgia (PHN). A live attenuated VZV vaccine, the first vaccine licensed for the prevention of HZ and PHN is not very effective, while a recombinant subunit vaccine provides higher and longer protection against HZ. In the present study, we developed a new adjuvant system CIA09A, which is composed of cationic liposomes, the Toll-like receptor 4 (TLR4) agonist de-O-acylated lipooligosaccharide, and Quillaja saponin fraction QS-21. We then determined its adjuvant activity for recombinant VZV glycoprotein E (gE) in mice. Co-lyophilization of the liposomal adjuvant formulation with gE did not abolish the immune-stimulating activity. In fact, the CIA09A-adjuvanted gE vaccine was highly effective in eliciting both humoral and cellular immune responses to the recombinant gE protein and VZV in a VZV-primed mouse model. Furthermore, the frequency of gE-specific polyfunctional CD4+ T cells expressing interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-2 was significantly increased in mice immunized with the adjuvanted vaccine. These data indicate that co-lyophilization of protein antigens with CIA09A enables development of a liposome-adjuvanted vaccine in a single vial to induce strong cell-mediated immunity required for vaccine efficacy. Thus, the CIA09A-adjuvanted gE vaccine warrants further development as a new prophylactic vaccine against HZ.

Live attenuated varicella-zoster virus vaccine does not induce HIV target cell activation

Varicella-zoster virus (VZV) is under consideration as a promising recombinant viral vector to deliver foreign antigens including HIV. However, new vectors have come under increased scrutiny, since trials with adenovirus serotype 5-vectored (Ad5-vectored) HIV vaccine demonstrated increased HIV risk in individuals with pre-immunity to the vector that was thought to be associated with mucosal immune activation (IA). Therefore, given the prospect of developing an HIV/VZV chimeric vaccine, it is particularly important to define the impact of VZV vaccination on IA. Healthy VZV-seropositive Kenyan women (n = 44) were immunized with high-dose live attenuated VZV vaccine, and we assessed the expression on CD4+ T cells isolated from blood, cervix, and rectum of IA markers including CD38 and HLA-DR and of markers of cell migration and tissue retention, as well as the concentration of genital and intestinal cytokines. A delayed-start group (n = 22) was used to control for natural variations in these parameters. Although immunogenic, VZV vaccination did not result in significant difference in the frequency of cervical activated (HLA-DR+CD38+) CD4+ T cells (median 1.61%, IQR 0.93%-2.76%) at 12 weeks after vaccination when compared with baseline (median 1.58%, IQR 0.75%-3.04%), the primary outcome for this study. VZV vaccination also had no measurable effect on any of the IA parameters at 4, 8, and 12 weeks after vaccination. This study provides the first evidence to our knowledge about the effects of VZV vaccination on human mucosal IA status and supports further evaluation of VZV as a potential vector for an HIV vaccine. ClinicalTrials.gov NCT02514018. Primary support from the Canadian Institutes for Health Research (CIHR). For other sources, see Acknowledgments.

Breadth and Functionality of Varicella-Zoster Virus Glycoprotein-Specific Antibodies Identified after Zostavax Vaccination in Humans.

Herpes zoster (HZ) (shingles) is the clinical manifestation of varicella-zoster virus (VZV) reactivation. HZ typically develops as people age, due to decreased cell-mediated immunity. However, the importance of antibodies for immunity against HZ prevention remains to be understood. The goal of this study was to examine the breadth and functionality of VZV-specific antibodies after vaccination with a live attenuated HZ vaccine (Zostavax). Direct enumeration of VZV-specific antibody-secreting cells (ASCs) via enzyme-linked immunosorbent spot assay (ELISPOT assay) showed that Zostavax can induce both IgG and IgA ASCs 7 days after vaccination but not IgM ASCs. The VZV-specific ASCs range from 33 to 55% of the total IgG ASCs. Twenty-five human VZV-specific monoclonal antibodies (MAbs) were cloned and characterized from single-cell-sorted ASCs of five subjects (>60 years old) who received Zostavax. These MAbs had an average of ∼20 somatic hypermutations per VH gene, similar to those seen after seasonal influenza vaccination. Fifteen of the 25 MAbs were gE specific, whereas the remaining MAbs were gB, gH, or gI specific. The most potent neutralizing antibodies were gH specific and were also able to inhibit cell-to-cell spread of the virus in vitro Most gE-specific MAbs were able to neutralize VZV, but they required the presence of complement and were unable to block cell-to-cell spread. These data indicate that Zostavax induces a memory B cell recall response characterized by anti-gE > anti-gI > anti-gB > anti-gH antibodies. While antibodies to gH could be involved in limiting the spread of VZV upon reactivation, the contribution of anti-gE antibodies toward protective immunity after Zostavax needs further evaluation.IMPORTANCE Varicella-zoster virus (VZV) is the causative agent of chickenpox and shingles. Following infection with VZV, the virus becomes latent and resides in nerve cells. Age-related declines in immunity/immunosuppression can result in reactivation of this latent virus, causing shingles. It has been shown that waning T cell immunity correlates with an increased incidence of VZV reactivation. Interestingly, serum with high levels of VZV-specific antibodies (VariZIG; IV immunoglobulin) has been administered to high-risk populations, e.g., immunocompromised children, newborns, and pregnant women, after exposure to VZV and has shown some protection against chickenpox. However, the relative contribution of antibodies against individual surface glycoproteins toward protection from shingles in elderly/immunocompromised individuals has not been established. Here, we examined the breadth and functionality of VZV-specific antibodies after vaccination with the live attenuated VZV vaccine Zostavax in humans. This study will add to our understanding of the role of antibodies in protection against shingles.

Varicella Virus Vaccination in the United States.

Varicella zoster virus (VZV) is the cause of chickenpox (varicella) and shingles (zoster), and was once responsible for over 4 million infections in the United States annually. The development of a live attenuated VZV vaccine was initially viewed with extreme skepticism. Nonetheless, a VZV vaccine was developed in the 1970s by Takahashi and his colleagues in Japan and was eventually licensed in the US. It is now known to be one of the safest and most effective vaccines available and is administered worldwide. Here are described important factors that contributed to the successful research and licensure of the highly successful VZV vaccine.

Immune response and reactogenicity of intradermal administration versus subcutaneous administration of varicella-zoster virus vaccine: an exploratory, randomised, partly blinded trial

The licensed live, attenuated varicella-zoster virus vaccine prevents herpes zoster in adults older than 50 years. We aimed to determine whether intradermal administration of zoster vaccine could enhance vaccine immunogenicity compared with conventional needle subcutaneous administration. In this randomised, dose-ranging study, adults aged 50 years or older who had a history of varicella or who had resided in a country with endemic varicella-zoster virus infection for 30 years or more were eligible. Participants received the approved full or a 1/3 dose of zoster vaccine given subcutaneously or one of four intradermal doses (full, 1/3, 1/10, or 1/27 dose) using the MicronJet600 device. The two subcutaneous doses and the four intradermal doses were randomised (1·5:1:1:1:1:1) by computer generated sequence with randomisation stratified by age (50-59 years or 60 years or older). The primary immunogenicity endpoint was the change from baseline in IgG antibody to varicella-zoster virus-specific glycoproteins (gpELISA) measured at 6 weeks. All patients were included in the primary and safety analyses. This study is registered with ClinicalTrials.gov, number NCT01385566. Between Sept 2, 2011, and Jan 13, 2012, 224 participants were enrolled from three clinics in the USA and 223 were randomly assigned: 52 to receive the full dose subcutaneous zoster vaccine, 34 to receive the 1/3 dose subcutaneous zoster vaccine, 34 to receive the full dose intradermal zoster vaccine, 35 to receive the 1/3 dose intradermal zoster vaccine, 34 to receive the 1/10 dose intradermal zoster vaccine, and 34 to receive the 1/27 dose intradermal zoster vaccine. Full dose zoster vaccine given subcutaneously resulted in a gpELISA geometric mean fold-rise (GMFR) of 1·74 (90% CI 1·48-2·04) at 6 weeks post-vaccination compared with intradermal administration which resulted in a significantly higher gpELISA GMFR of 3·25 (2·68-3·94; p<0·0001), which also remained high at 18 months. An apparent dose-response relation was observed with intradermal administration (1/3 dose subcutaneous GMFR 1·64 [90% CI 1·36-1·99], 1/3 dose intradermal 2·58 (2·13-3·13), 1/10 dose intradermal 2·22 [1·83-2·69], and 1/27 dose intradermal 1·64 [1·35-2·00]). Each partial dose of zoster vaccine given intradermaly had a gpELISA GMFR comparable to that of full dose zoster vaccine given subcutaneously. Transient erythema and induration were more common after intradermal administration (31% erythema for full subcutaneous dose and 77% for intradermal dose). Intradermal zoster vaccine showed a greater increase in varicella-zoster virus gpELISA antibody compared with subcutaneous zoster vaccine at comparable doses. Larger and longer studies of intradermal administration of live, attenuated zoster vaccine are needed to provide convincing evidence of improved cell mediated immunity. Merck & Co Inc.

Immunogenicity and safety of co-immunization of children with live attenuated varicella-zoster virus vaccine and live attenuated hepatitis A virus vaccine

Objective To investigate the immunogenicity and safety of co-immunization of children with live attenuated varicella-zoster virus (VZV) vaccine and live attenuated hepatitis A virus (HAV) vaccine. Methods A total of 686 children aged 18-24 months were recruited in Henan province of China and divided into three groups. Children in the three groups were respectively immunized with live attenuated VZV vaccine or live attenuated HAV vaccine alone or in combination. Blood samples were collected from all subjects before and one month after vaccination for the detection of seroconversion and seropositive rates. Occurrence of adverse events was monitored for safety evaluation. Antibody membrane immune-fluorescence assay and enzyme immunoassay were performed to detect the antibodies against VZV and HAV, respectively. Results The seroconversion rates of anti-VZV antibody were both 100% in children received co-immunization or VZV vaccine immunization alone. The geometric mean titer (GMT) of anti-VZV antibody in co-immunization group was higher than that of VZV vaccine immunization group (P<0.001). The GMT and seroconversion rate of anti-HAV antibody in children immunized with live attenuated VZV vaccine and live attenuated HAV vaccine were similar to those immunized with live attenuated HAV vaccine alone (P=0.94, P=0.77). Adverse reactions were reported in 156 subjects with a rate of 22.74%, mainly manifested as fever and swelling. No other adverse reactions were observed. No significant differences in the adverse events were observed between the three groups. Conclusion Co-immunization children with live attenuated varicella vaccine and live attenuated hepatitis A virus vaccine provided equivalent immunogenicity and safety in comparison with immunization the two vaccines alone, indicating the feasibility of co-immunization strategy. Key words: Live attenuated varicella vaccine; Live attenuated hepatitis A virus vaccine; Co-immunization; Immunogenicity; Safety

Herpes Zoster: the rationale for the introduction of vaccination in Italy.

Herpes Zoster (HZ) and its main complication, post-herpetic neuralgia (PHN), represent an important public health issue because of their relevant burden within older adult population and the actual suboptimal therapeutic management of the diseases. Incidences of HZ and PHN are comparable all over the world and are closely related with the population age. Epidemiological data collected in Italy about HZ and its complications confirmed the trend registered in North America and Europe. Moreover HZ related burden is exacerbated by a significant economic impact related to both direct and indirect costs. Since 2006 a live, attenuated varicella zoster virus vaccine, that contains VZV Oka strain [Zostavax, Merck & Co., Inc.], was licensed for the prevention of HZ and PHN in adults aged ≥ 60 years. Since 2011, the licensure has been extended to adults between 50 and 59 years. The vaccine has demonstrated a good immunogenicity, efficacy and safety profiles in two pivotal phase III clinical trials and the effectiveness was further confirmed after vaccine licensure. Pharmaco-economic studies concluded that HZ vaccine is cost-effective in most European countries and generally supported the economic value of this vaccination. The vaccine is actually recommended in USA, Canada and several European countries. The opportunity to reduce the burden of these diseases by the recommendation of HZ vaccination have been evaluated and suggested also in our Country and some Regions have been recently introduced the vaccine in their immunization plan. If the good results, already obtained with HZ vaccine in other countries, will be confirmed by these Italian pilot experiences, vaccination programs should be made uniform in all Country in order to ensure an equitable offer of this important preventive tool.

Development of an IFN-&amp;#947; ELISpot Assay to Assess Varicella-Zoster Virus-specific Cell-mediated Immunity Following Umbilical Cord Blood Transplantation

Varicella zoster virus (VZV) is a significant cause of morbidity and mortality following umbilical cord blood transplantation (UCBT). For this reason, antiherpetic prophylaxis is administrated systematically to pediatric UCBT recipients to prevent complications associated with VZV infection, but there is no strong, evidence based consensus that defines its optimal duration. Because T cell mediated immunity is responsible for the control of VZV infection, assessing the reconstitution of VZV specific T cell responses following UCBT could provide indications as to whether prophylaxis should be maintained or can be discontinued. To this end, a VZV specific gamma interferon (IFN-γ) enzyme-linked immunospot (ELISpot) assay was developed to characterize IFN-γ production by T lymphocytes in response to in vitro stimulation with irradiated live attenuated VZV vaccine. This assay provides a rapid, reproducible and sensitive measurement of VZV specific cell mediated immunity suitable for monitoring the reconstitution of VZV specific immunity in a clinical setting and assessing immune responsiveness to VZV antigens.

Development of an IFN-γ ELISpot assay to assess varicella-zoster virus-specific cell-mediated immunity following umbilical cord blood transplantation.

Varicella zoster virus (VZV) is a significant cause of morbidity and mortality following umbilical cord blood transplantation (UCBT). For this reason, antiherpetic prophylaxis is administrated systematically to pediatric UCBT recipients to prevent complications associated with VZV infection, but there is no strong, evidence based consensus that defines its optimal duration. Because T cell mediated immunity is responsible for the control of VZV infection, assessing the reconstitution of VZV specific T cell responses following UCBT could provide indications as to whether prophylaxis should be maintained or can be discontinued. To this end, a VZV specific gamma interferon (IFN-γ) enzyme-linked immunospot (ELISpot) assay was developed to characterize IFN-γ production by T lymphocytes in response to in vitro stimulation with irradiated live attenuated VZV vaccine. This assay provides a rapid, reproducible and sensitive measurement of VZV specific cell mediated immunity suitable for monitoring the reconstitution of VZV specific immunity in a clinical setting and assessing immune responsiveness to VZV antigens.

Live Attenuated Varicella-Zoster Vaccine in Hematopoietic Stem Cell Transplantation Recipients

Hematopoietic stem cell transplantation (HSCT) recipients are at risk for varicella-zoster virus (VZV) reactivation. Vaccination may help restore VZV immunity; however, the available live attenuated VZV vaccine (Zostavax) is contraindicated in immunocompromised hosts. We report our experience with using a single dose of VZV vaccine in 110 adult autologous and allogeneic HSCT recipients who were about 2 years after transplantation, free of graft-versus-host disease, and not receiving immunosuppression. One hundred eight vaccine recipients (98.2%) had no clinically apparent adverse events with a median follow-up period of 9.5 months (interquartile range, 6 to 16; range, 2 to 28). Two vaccine recipients (1.8%) developed a skin rash (one zoster-like rash with associated pain, one varicella-like) within 42 days post-vaccination that resolved with antiviral therapy. We could not confirm if these rashes were due to vaccine (Oka) or wild-type VZV. No other possible cases of VZV reactivation have occurred with about 1178 months of follow-up. Live attenuated zoster vaccine appears generally safe in this population when vaccinated as noted; the overall vaccination risk needs to be weighed against the risk of wild-type VZV disease in this high-risk population.

Evaluation of VZV‐specific cell‐mediated immunity in adults infected with HIV‐1 by using a simple IFN‐γ release assay

The development of herpes zoster is associated with reduced varicella zoster virus (VZV)-specific cell-mediated immune (CMI) reactions. In this study, VZV-specific CMI reactions in 42 anti-VZV-IgG antibody-positive adults infected with HIV-1 were evaluated by measuring the IFN-γ production levels in whole blood in response to stimulation with ultraviolet light-inactivated live attenuated VZV vaccine. The median VZV-specific IFN-γ production level in all patients was 63 pg/ml. Antiretroviral therapy (ART)-naïve patients with an AIDS-defining illness (HIV classification category C) had significantly lower IFN-γ production than ART-naïve patients in categories A and B and patients receiving ART (P=0.0194 and P=0.0046, respectively). IFN-γ production increased significantly in patients within 1 month of the onset of recurrent VZV disease and at more than 1 year from onset, compared with patients who had never had recurrent VZV disease (P=0.0396 and P=0.0484, respectively). In multivariate analyses, category C and history of recurrent VZV disease were significant factors affecting IFN-γ production. Levels of IFN-γ were measured before and after ART in seven ART-naïve patients with no history of recurrent VZV disease, and no significant changes were observed. The results indicate that VZV-specific CMI reactions were reduced in patients with an AIDS-defining illness and enhanced in patients with a history of recurrent VZV disease, but not enhanced by ART alone. Vaccination may be necessary to inhibit the development of herpes zoster in patients receiving ART; this IFN-γ releasing assay is one useful method for evaluating VZV-specific CMI reactions in clinical settings.

Cost-effectiveness of vaccination of the elderly against herpes zoster in The Netherlands

BackgroundEach year a substantial number of Dutch elderly suffers from herpes zoster (HZ), caused by the reactivation of the varicella zoster virus (VZV). A potential complication of HZ is postherpetic neuralgia (PHN) which results in a prolonged loss of quality of life. A large randomized clinical trial, labelled the Shingles Prevention study (SPS), demonstrated that a live attenuated VZV vaccine can reduce the incidence of HZ and PHN. ObjectiveWe aimed to estimate the incremental cost-effectiveness ratio (ICER) of vaccination of the elderly against HZ versus no such vaccination in The Netherlands. MethodsA cohort model was developed to compare the costs and effects in a vaccinated and a non-vaccinated age- and gender-stratified cohort of immune-competent elderly. Vaccination age was varied from 60 to 75 years. Data from published literature such as the SPS were used for transition probabilities. The study was performed from the societal as well as the health care payer's perspective and results were expressed in euros per quality-adjusted life year (QALY) gained. ResultsIn the base case, we estimated that vaccination of a cohort of 100,000 60-year-olds would prevent 4136 cases of HZ, 305 cases of PHN resulting in a QALY-gain of 209. From the societal perspective, a total of €1.9 million was saved and the ICER was €35,555 per QALY gained when a vaccine price of €87 was used. Vaccination of women resulted in a lower ICER than vaccination of men (€33,258 vs. €40,984 per QALY gained). The vaccination age with the most favourable ICER was 70 years (€29,664 per QALY gained). Parameters with a major impact on the ICER were the vaccine price and HZ incidence rates. In addition, the model was sensitive to utility of mild pain, vaccine efficacy at the moment of uptake and the duration of protection induced by the vaccine. ConclusionVaccination against HZ might be cost-effective for ages ranging from 60 to 75 when a threshold of €50,000 per QALY gained would be used, at €20,000 per QALY this might not be the case. Additional information on the duration of vaccine-protection is needed to further optimize cost-effectiveness estimations.

Safety of Zostavax™—A cohort study in a managed care organization

BackgroundZostavax™ is a live, attenuated varicella-zoster virus vaccine indicated for the prevention of herpes zoster (shingles). An observational post-licensure (Phase IV) study was conducted at Kaiser Permanente Northern California (KPNC), a US managed care organization, to assess the safety of zoster vaccine in people 60 years of age or older, vaccinated in routine medical care. MethodsWe performed a cohort study, comparing rates of clinical events resulting in hospitalizations or emergency department visits in a 42-day risk time period immediately following vaccination with rates in the same cohort in a subsequent comparison time period. The study data were reviewed and interpreted by an external safety review committee of 3 independent experts. ResultsApproximately 29,000 people≥60 years of age were vaccinated with zoster vaccine from July 2006 to November 2007. Of the 386 comparisons performed for the main analysis, 4 had an increased relative risk with a nominal p-value≤0.05. After medical records review, the timing of these conditions and procedures was found to be often prior to vaccination, and no clear increase in health events was observed in the risk period following vaccination compared to later. Persons receiving zoster vaccine appeared to be in their optimal health at the time of vaccination, which led to an apparent protective effect of the vaccine for some health outcomes, due to the study design. ConclusionsThere was no evidence of a safety concern for zoster vaccine.

A Phase 1/2 Clinical Trial Evaluating Safety and Immunogenicity of a Varicella Zoster Glycoprotein E Subunit Vaccine Candidate in Young and Older Adults

An adjuvanted recombinant varicella zoster virus (VZV) subunit vaccine is being developed for the prevention of herpes zoster and its complications. In a phase I/II, open-label, randomized, parallel-group study, older adults (50-70 years) received 2 doses 2 months apart of an adjuvanted recombinant glycoprotein E vaccine (HZ/su; n = 45), a live attenuated Oka strain VZV vaccine (OKA; n = 45), or HZ/su and OKA administered concomitantly (n = 45). To evaluate safety prior to administration in older adults, young adults (18-30 years) were vaccinated with 2 doses 2 months apart of HZ/su (n = 10) or OKA (n = 10). Safety and immunogenicity were assessed up to 42 months for older adults immunized with HZ/su and up to 12 months for all others. Few grade 3 events and no severe adverse events were reported. Fatigue, myalgia, headache, and injection site pain were the most common solicited reactions for HZ/su and occurred more frequently than with OKA. CD4(+) T-cell and humoral immune responses were much higher with HZ/su than with OKA and remained elevated until 42 months. Addition of OKA to HZ/su did not increase immunogenicity. In this study, HZ/su adjuvanted subunit vaccine was well tolerated and more immunogenic than a live attenuated VZV vaccine. Clinical Trial registration. NCT00492648 and NCT00492648.

Genome-Wide Mutagenesis Reveals That ORF7 Is a Novel VZV Skin-Tropic Factor

The Varicella Zoster Virus (VZV) is a ubiquitous human alpha-herpesvirus that is the causative agent of chicken pox and shingles. Although an attenuated VZV vaccine (v-Oka) has been widely used in children in the United States, chicken pox outbreaks are still seen, and the shingles vaccine only reduces the risk of shingles by 50%. Therefore, VZV still remains an important public health concern. Knowledge of VZV replication and pathogenesis remains limited due to its highly cell-associated nature in cultured cells, the difficulty of generating recombinant viruses, and VZV's almost exclusive tropism for human cells and tissues. In order to circumvent these hurdles, we cloned the entire VZV (p-Oka) genome into a bacterial artificial chromosome that included a dual-reporter system (GFP and luciferase reporter genes). We used PCR-based mutagenesis and the homologous recombination system in the E. coli to individually delete each of the genome's 70 unique ORFs. The collection of viral mutants obtained was systematically examined both in MeWo cells and in cultured human fetal skin organ samples. We use our genome-wide deletion library to provide novel functional annotations to 51% of the VZV proteome. We found 44 out of 70 VZV ORFs to be essential for viral replication. Among the 26 non-essential ORF deletion mutants, eight have discernable growth defects in MeWo. Interestingly, four ORFs were found to be required for viral replication in skin organ cultures, but not in MeWo cells, suggesting their potential roles as skin tropism factors. One of the genes (ORF7) has never been described as a skin tropic factor. The global profiling of the VZV genome gives further insights into the replication and pathogenesis of this virus, which can lead to improved prevention and therapy of chicken pox and shingles.

Identification of an Important Immunological Difference between Virulent Varicella-Zoster Virus and Its Avirulent Vaccine: Viral Disruption of Dendritic Cell Instruction

Virulent varicella-zoster virus (VZV) can spread in immunocompetent humans, resulting in symptoms mostly of the skin. In contrast, vaccine Oka (V-Oka), the attenuated VZV vaccine strain, only rarely causes clinical reactions. The mechanisms underlying these pathogenetic differences are unclear. In this study, we comparatively analyzed the ability of virulent VZV and V-Oka to modulate instruction of dendritic cells (DCs) by innate signals. DCs isolated from normal human skin were susceptible to infection with VZV and V-Oka. Moreover, inflammatory DCs, which play a crucial role in the stimulation of Th1 immune responses, accumulated in herpes zoster lesions. Infection of inflammatory DCs generated in vitro with virulent VZV or V-Oka resulted in upregulation of CD1c. Upon coculture with CD1c-restricted innate cells, DCs developed a mature phenotype whether infected with virulent VZV or V-Oka. Intriguingly, a striking difference was detected on the functional level. The release of IFN-gamma and IL-12, the signature cytokines of Th1 responses, was enhanced by V-Oka but blocked by virulent VZV. V-Oka and virulent VZV efficiently synergized with CD40L, eliminating the possibility that CD40 signaling was a target of VZV-associated immune evasion. Instead, virulent VZV selectively interfered with signaling through TLR2, which is known to sense VZV. Thus, virulent VZV subverts Th1-promoting instruction of human DCs by blocking TLR2-mediated innate signals that prime IL-12 production by DCs. Taken together, our results demonstrate a novel immune-evasion mechanism of virulent VZV that has been lost during the attenuation process leading to the VZV vaccine strain.