Risk of herpes zoster according to past history in the general population: The Japanese Shozu herpes zoster study.

Immunity is known to persist after vaccination for varicella zoster virus, but the duration of immunity in patients who develop herpes zoster (HZ) remains unknown. To investigate the association between a past history of HZ and its occurrence in the general population. The Shozu HZ (SHEZ) cohort study included data for 12 299 individuals aged ≥50 years with information on their HZ history. Cross-sectional and 3-year follow-up studies were carried out to analyze the associations between a history of HZ (yes <10 years, yes ≥10 years, no) and the proportion of positive varicella zoster virus skin test results (erythema diameter ≥5 mm) and the risk of HZ after adjusting for potential confounding factors including age, sex, body mass index, smoking status, sleep duration, and mental stress. The incidences of positive skin test results were 87.7% (470/536) for individuals with a history of HZ <10 years ago, 82.2% (396/482) for those with a history of HZ ≥10 years, and 80.2% (3614/4509) for those with no history of HZ. The multivariable odds ratios (95% confidence intervals) of erythema diameter ≥5 mm were 2.07 (1.57-2.73) and 1. 39 (1.08-1.80) for individuals with a history <10 years and ≥10 years ago, respectively, compared with no history. The corresponding multivariable hazard ratios of HZ were 0.54 (0.34-0.85) and 1.16 (0.83-1.61), respectively. A past history of HZ <10 years ago may reduce the occurrence of HZ.

Predictors of herpes zoster severity and immune responses according to pain trajectories: A community-based prospective cohort study.

The authors aimed to identify determinants of the clinical course of herpes zoster and immunological responses, focusing on pain trajectories. This prospective community-based cohort study involved the analysis of responses to a valid pain survey provided by 375 patients diagnosed with herpes zoster based on clinical symptoms and virus identification by polymerase chain reaction. The authors analyzed most patients for humoral/cell-mediated immune response against varicella-zoster virus at the onset and 3 months post-onset. Six months post-initial visit, patients self-reported pain on a scale of 0 (no pain) to 5 (extremely strong pain) at up to 18 time points. Moreover, the pain trajectories were traced using group-based trajectory modeling. Subsequently, the authors used analysis of covariance to explore predictors and the humoral/cell-mediated immune response according to the pain trajectories. In addition, humoral/cell-mediated immune responses were assessed among each trajectory using paired t tests. Amon the five identified trajectories, two were isolated that particularly developed postherpetic neuralgia, with or without severe acute pain. Cancer therapy and corticosteroid use before herpes zoster onset specifically predicted postherpetic neuralgia without severe acute pain. In contrast, prescription of nonsteroidal anti-inflammatory drugs was uniquely associated with postherpetic neuralgia accompanied by severe acute pain. The aforementioned trajectories with postherpetic neuralgia showed increased antibodies and decreased cell-mediated immunity compared with those without postherpetic neuralgia. The authors could successfully distinguish between postherpetic neuralgia trajectories with and without severe acute pain. The identified key predictors and immunological responses against varicella-herpes zoster contribute further evidence to our understanding of the clinical features of herpes zoster and postherpetic neuralgia.

Longitudinal changes in cell-mediated immunity after varicella-zoster virus skin test in the general population; Shozu Herpes Zoster Study: SHEZ study.

Varicella-zoster virus-specific cell-mediated immunity has been associated with the onset and severity of herpes zoster (HZ), and the administration of the HZ vaccine enhanced the immunity. However, limited data is available on the duration of cell-mediated immunity enhancement by soluble antigen of varicella-zoster virus (VZV) skin test. A prospective, community-based cohort study was conducted in Shozu County, Kagawa Prefecture, Japan. Repeated VZV skin tests containing inactivated VZV antigen and blood tests were performed on 365 subjects aged 60 years and older at baseline, 1, 2, and 3 years later. The differential immunity indices of VZV over time for cell-mediated and humoral immunity were evaluated. VZV skin test reaction and ELISpot counts increased significantly at 1, 2, and 3 years later compared to the baseline. However, humoral immunity indices did not change materially over time. Soluble antigen by VZV skin test enhanced VZV-specific cell-mediated immunity, and it persisted for at least 1 year. In addition, the inoculation with inactivated antigens every year by VZV skin test continued to enhance VZV-specific cell-mediated immunity after 2 and 3 years.

Versatile live-attenuated SARS-CoV-2 vaccine platform applicable to variants induces protective immunity.

Live-attenuated vaccines are generally highly effective. Here, we aimed to develop one against SARS-CoV-2, based on the identification of three types of temperature-sensitive (TS) strains with mutations in nonstructural proteins (nsp), impaired proliferation at 37°C-39°C, and the capacity to induce protective immunity in Syrian hamsters. To develop a live-attenuated vaccine, we generated a virus that combined all these TS-associated mutations (rTS-all), which showed a robust TS phenotype in vitro and high attenuation in vivo. The vaccine induced an effective cross-reactive immune response and protected hamsters against homologous or heterologous viral challenges. Importantly, rTS-all rarely reverted to the wild-type phenotype. By combining these mutations with an Omicron spike protein to construct a recombinant virus, protection against the Omicron strain was obtained. We show that immediate and effective live-attenuated vaccine candidates against SARS-CoV-2 variants may be developed using rTS-all as a backbone to incorporate the spike protein of the variants.

The association of family history of herpes zoster and the risk of incident herpes zoster: the SHEZ Study.

BACKGROUND: We investigated whether family histories of herpes zoster (HZ) are associated with the risk of incident HZ in a Japanese population. METHODS: A total of 12,522 Japanese residents aged ≥50 years in Shozu County participated in the baseline survey between December 2008 and November 2009 (the participation rate = 72.3%). They were interviewed at baseline by research physicians regarding the registrants' history of HZ. A self-administered questionnaire survey was conducted to evaluate the potential confounding factors. 10,530 participants without a history of HZ were followed up to ascertain the incidence of HZ during 3-years follow-up until the end of November 2012 with Japanese nationals. We estimated hazard ratios (HRs) of incident HZ according to first-degree family histories using the Cox proportional hazard regression after adjusting for age, sex, and other potential confounding factors. RESULTS: Compared to no HZ history of each family member, a history of brother or sister was associated with a higher risk of incident HZ while histories of father and mother were not. The multivariable HR (95%CI) of incident HZ for a history of brother or sister was 1.67 (1.04-2.69). When comparing to no family histories of all first-degree relatives, the multivariable HRs (95%CIs) were 1.34 (0.77-2.34) for a history of brother or sister alone, but 4.81 (1.78-13.00) for a history of mother plus brother or sister. As for the number of family histories, the multivariable HRs (95%CIs) were 1.08 (0.76-1.54) for one relative (father, mother, or brother or sister) and 2.75 (1.13-6.70) for two or more relatives. CONCLUSION: Family histories of mother plus brother or sister and two or more first-degree relatives were associated with a higher risk of incident HZ.

Immunogenicity of varicella-zoster virus vaccine by different routes of administration: Comparable vaccination efficacy of one-fifth dose intradermal vaccination to conventional subcutaneous vaccination.

BACKGROUND: The live attenuated varicella-zoster virus (VZV) vaccine is used for the prevention of chickenpox and herpes zoster; however, there have been few studies on the immunogenicity of intradermal vaccination. OBJECTIVE: To compare the immunogenicity between subcutaneous and intradermal VZV vaccination. METHODS: Thirty healthy participants aged 50-75 who developed erythema less than 10 mm in diameter in VZV skin test were examined. Thirteen participants received full dose of VZV vaccine subcutaneously and 17 participants received one-fifth dose of vaccine intradermally. Immunogenicity to VZV was determined by VZV skin test reaction, proliferation of VZV-specific memory T cells, levels of VZV-specific serum antibody, and cytokine production from peripheral blood cells. RESULTS: VZV skin test reaction was similar between two groups. VZV-specific memory T cells were significantly increased only in the intradermal injection group. The increase of VZV-specific memory T cells correlated with Th1, Th2 and Th17 cytokines and cytotoxic molecules. No serious adverse events were observed in either group after vaccination. CONCLUSION: Intradermal injection with one-fifth dose VZV vaccine showed a similar or greater effect on VZV-specific cellular immunostimulation than conventional subcutaneous injection. These findings suggest that one-fifth dose intradermal vaccination may have a comparable preventive effect to conventional subcutaneous injection.

Risk of Herpes Zoster in Relation to Body Mass Index Among Residents Aged ≥50 Years: The Shozu Herpes Zoster Study.

BACKGROUND: The impact of body mass index on incidence of herpes zoster is unclear. This study investigated whether body mass index was associated with a history of herpes zoster and incidence during a 3-year follow-up, using data from a prospective cohort study in Japan. METHODS: In total, 12,311 individuals were included in the cross-sectional analysis at baseline, of whom 1,818 with a history of herpes zoster were excluded from the incidence analysis, leaving 10,493 individuals. Body mass index (kg/m2) was classified into three categories (underweight: <18.5; normal: 18.5 to <25; and overweight: ≥25). To evaluate the risk of herpes zoster, we used a logistic regression model for prevalence and a Cox proportional hazard regression model for incidence. RESULTS: Being overweight or underweight was not associated with herpes zoster prevalence at baseline. The multivariate hazard ratios of herpes zoster incidence for overweight versus normal-weight groups were 0.67 (95% confidence interval, 0.51-0.90) in all participants, and 0.57 (95% confidence interval, 0.39-0.83) in women, with no significant difference for men. CONCLUSION: Being overweight was associated with a lower incidence of herpes zoster than being normal weight in older Japanese women.

Quantification of a cell-mediated immune response against varicella zoster virus by assessing responder CD4high memory cell proliferation in activated whole blood cultures.

BACKGROUND: Herpes zoster (HZ) is caused by reactivation of a latent varicella zoster virus (VZV). The potential to develop HZ increases with age due to waning of memory cell-mediated immunity (CMI), mainly the CD4 response. Therefore, VZV-CD4-memory T cells (CD4-M) count in blood could serve as a barometer for HZ protection. However, direct quantification of these cells is known to be difficult because they are few in number in the blood. We thus developed a method to measure the proliferation level of CD4-M cells responding to VZV antigen in whole blood culture. METHODS: Blood samples were collected from 32 children (2-15 years old) with or without a history of varicella infection, 18 young adults (28-45 years old), and 80 elderly (50-86 years old) with a history of varicella infection. The elderly group was vaccinated, and blood samples were taken 2 months and 1 year after VZV vaccination. Then, 1 mL of blood was mixed with VZV, diluted 1/10 in medium, and cultured. CD4-M cells were identified and measured by flow cytometry. RESULTS: There was distinct proliferation of CD3+CD4highCD45RA-RO+ (CD4high-M) cells specific to VZV antigen at day 9. The majority of CD4high-M cells had the effector memory phenotype CCR7- and was granzyme B-positive. CD4high-M cells were detected in blood culture from varicella-immune but not varicella-non-immune children. Meanwhile, a higher level of CD4high-M proliferation was observed in young adults than in the elderly. The CD4high-M proliferation level was boosted 2 months after VZV vaccination and maintained for at least 1 year in the elderly. CONCLUSION: Quantifying VZV responder CD4high -M cell proliferation is a convenient way to measure VZV CMI using small blood volumes. Our method can be applied to measure VZV vaccine-induced CMI in the elderly. Clinical study registry numbers: (www.clinicaltrials.jp) 173532 and 183985.

Sleep Shortage Is Associated With Postherpetic Neuralgia Development Through Hyperesthesia and Acute Pain Intensity: A Community-Based Prospective Cohort Study.

OBJECTIVES: There have been no community-based studies investigating the association between sleep duration and postherpetic neuralgia (PHN) development. The aim of the current study was to examine the association of sleep with herpes zoster (HZ) incidence and PHN. METHODS: In total, 12,329 residents (ages 50 to 103 years) of Shozu County, Japan, participated in our study from December 2009 to November 2010 and were followed up for 3 years. At baseline, the participants completed self-administered health questionnaires, including those on usual sleep duration. Three dermatologists diagnosed HZ on the basis of clinical symptoms and virus identification testing by polymerase chain reaction and serological tests, and evaluated pain using a modified Zoster Brief Pain Inventory survey form via telephone. We used a Cox proportional hazard regression model to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of incident HZ and PHN. We also performed mediation analysis to examine whether hyperesthesia and acute pain intensity mediated the association between sleep shortage and chronic pain intensity. RESULTS: During follow-up, 400 cases of HZ were identified. Of these, 55 participants developed PHN. Sleep duration was not associated with HZ incidence. Sleep shortage increased the risk for PHN (HR 2.02 [95% CI: 1.06 to 3.85]). Hyperesthesia and acute pain intensity mediated the association between sleep shortage and chronic pain intensity (indirect/total effect ratio = 50% mediation). CONCLUSIONS: Sleep shortage was associated with increased risk for PHN, and hyperesthesia and acute pain intensity appeared to mediate this association. Sleep shortage may be a novel risk factor for PHN.

Associations of Perceived Mental Stress, Sense of Purpose in Life, and Negative Life Events With the Risk of Incident Herpes Zoster and Postherpetic Neuralgia: The SHEZ Study.

In the present population-based prospective study, we examined the associations of psychosocial factors with the incidence of herpes zoster (HZ) and postherpetic neuralgia (PHN). Data were collected from 12,359 participants (≥50 years of age) who answered a self-completed health questionnaire in the Shozu County of Kagawa Prefecture in Japan. During a 3-year follow-up between December 2008 and November 2012, HZ and PHN were diagnosed in 400 and 79 subjects, respectively. We used Cox regression analysis to estimate hazard ratios of incident HZ and PHN according to psychosocial factors, adjusting for age, sex, histories of HZ, cancer, and diabetes, smoking and drinking habits, and time from disease onset to treatment. Men with high levels of mental stress were twice as likely to be at risk for incident HZ. The risk of incident HZ was approximately 60% lower among men and women who reported a high sense of purpose in life. Women who experienced negative life events-particularly changes in their work, living environment, and relationships-had a 2- to 3-fold higher risk of incident PHN. Psychosocial factors such as perceived mental stress, sense of purpose in life, and negative life events may contribute to the development of HZ and PHN in the general population.

Relationship between cell-mediated immunity to Varicella-Zoster virus and aging in subjects from the community-based Shozu Herpes Zoster study.

Age-related declines in cell-mediated immunity (CMI) are associated with the incidence and severity of Herpes Zoster (HZ) infection. However, the level of Varicella-Zoster virus (VZV)-specific CMI associated with disease onset is unclear. This study aimed to examine factors associated with VZV-specific CMI, as measured by an interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISPOT) assay, in a Japanese cohort. The study enrolled 365 subjects aged 60 years and over, all of whom were taking part in the Shozu Herpes Zoster (SHEZ) study and had undergone four sets of blood and intradermal reaction tests during a 3 year follow-up period. The VZV-specific immunity profile of each subject was assessed, and linear mixed effects models were constructed to analyze IFN-γ ELISPOT results in association with a combination of factors. The model that best explained the IFN-γ ELISPOT results was selected using the Akaike Information Criteria. The best-fit model consisted of age group as the only explanatory fixed-effect variable. The model showed that VZV-specific CMI, quantified as numbers of spots on the ELISPOT assay, among subjects aged 70-79 was on average 10.30 points lower than that among subjects aged 60-69. There was no statistically significant difference between subjects aged 70-79 and those aged 80-89. Age was the only factor significantly associated with the level of VZV-specific CMI, as measured by the IFN-γ ELISPOT assay. These results may represent an important step towards quantifying the relationship between VZV-specific CMI and the onset of HZ. J. Med. Virol. 89:313-317, 2017. © 2016 Wiley Periodicals, Inc.

Clinical and immunologic features of recurrent herpes zoster (HZ).

BACKGROUND: Recurrent herpes zoster (HZ) is thought to be rare, but there have been few large-scale studies of recurrent HZ. OBJECTIVE: We conducted a large-scale prospective cohort study to characterize recurrent HZ. METHODS: We examined 12,522 participants aged 50 years or older in Shozu County and followed them up for 3 years. We compared the incidence of HZ and postherpetic neuralgia, severity of skin lesions and acute pain, cell-mediated immunity, and varicella-zoster virus-specific antibody titer between primary and recurrent HZ. RESULTS: A total of 401 participants developed HZ: 341 with primary HZ and 60 with recurrent HZ. Skin lesions and acute pain were significantly milder and the incidence of postherpetic neuralgia was lower in patients aged 50 to 79 years with recurrent HZ than in those with primary HZ. Varicella-zoster virus skin test induced a stronger reaction in patients aged 50 to 79 years with recurrent HZ than in those with primary HZ. LIMITATIONS: Information on previous HZ episodes was self-reported by participants, so it could not be confirmed that they actually had a history of HZ. CONCLUSION: Recurrent HZ was associated with milder clinical symptoms than primary HZ, probably because of stronger varicella-zoster virus-specific cell-mediated immunity in the patients with recurrence.

Deep Sequencing of Distinct Preparations of the Live Attenuated Varicella-Zoster Virus Vaccine Reveals a Conserved Core of Attenuating Single-Nucleotide Polymorphisms.

UNLABELLED: The continued success of the live attenuated varicella-zoster virus vaccine in preventing varicella-zoster and herpes zoster is well documented, as are many of the mutations that contribute to the attenuation of the vOka virus for replication in skin. At least three different preparations of vOka are marketed. Here, we show using deep sequencing of seven batches of vOka vaccine (including ZostaVax, VariVax, VarilRix, and the Oka/Biken working seed) from three different manufacturers (VariVax, GSK, and Biken) that 137 single-nucleotide polymorphism (SNP) mutations are present in all vaccine batches. This includes six sites at which the vaccine allele is fixed or near fixation, which we speculate are likely to be important for attenuation. We also show that despite differences in the vaccine populations between preparations, batch-to-batch variation is minimal, as is the number and frequency of mutations unique to individual batches. This suggests that the vaccine manufacturing processes are not introducing new mutations and that, notwithstanding the mixture of variants present, VZV live vaccines are extremely stable. IMPORTANCE: The continued success of vaccinations to prevent chickenpox and shingles, combined with the extremely low incidence of adverse reactions, indicates the quality of these vaccines. The vaccine itself is comprised of a heterogeneous live attenuated virus population and thus requires deep-sequencing technologies to explore the differences and similarities in the virus populations between different preparations and batches of the vaccines. Our data demonstrate minimal variation between batches, an important safety feature, and provide new insights into the extent of the mutations present in this attenuated virus.

Incidences of Herpes Zoster and Postherpetic Neuralgia in Japanese Adults Aged 50 Years and Older From a Community-based Prospective Cohort Study: The SHEZ Study.

BACKGROUND: Many cross-sectional studies have examined the incidences of herpes zoster (HZ) and postherpetic neuralgia (PHN), but prospective studies in Japanese older adults are lacking. Therefore, we conducted a community-based prospective cohort study to determine the incidence in Japanese adults aged ≥50 years. METHODS: We recruited 12 522 participants from Shozu County, Kagawa Prefecture, between December 2008 and November 2009 and followed participants for 3 years. When a subject presented with symptoms suggestive of HZ, they were examined at collaborating medical institutions and cooperated with onset and recovery surveys (eg, measurement of varicella zoster virus-specific immunity and a pain survey). The hazard ratios (HRs) of HZ and PHN according to sex and age were analyzed by Cox regression analysis with a significance level of 5%. RESULTS: The incidence of HZ was 10.9/1000 person-years (men: 8.5/1000 person-years; women: 12.8/1000 person-years) and was significantly higher in women than in men (HR 1.5; 95% confidence interval, 1.2-1.8). The incidence of PHN was 2.1/1000 person-years (men: 1.7/1000 person-years; women: 2.4/1000 person-years), with no significant sex differences. A total of 19% of HZ cases progressed to PHN; no sex-specific difference in the proportion of PHN cases was observed. CONCLUSIONS: We clarified the accurate incidences of HZ and PHN in a population of Japanese older adults. These incidences increased with age. HZ incidence was higher in women than in men, while PHN incidence did not differ markedly between the sexes.

Evaluation of varicella zoster virus-specific cell-mediated immunity by using an interferon-γ enzyme-linked immunosorbent assay.

BACKGROUND: Administration of the varicella vaccine induces both varicella-zoster virus (VZV)-specific humoral and cell-mediated immunity (CMI). OBJECTIVE: To assess VZV-CMI, we developed an interferon γ enzyme-linked immunosorbent assay (IFN-γ ELISA) that measures the quantity of total IFN-γ in culture supernatants of human peripheral blood mononuclear cells. STUDY DESIGN: We evaluated this method by comparing the pre- and post-vaccination immune response in peripheral blood mononuclear cells of 30 healthy children who were administered an initial varicella vaccination at Konan Kosei hospital. RESULTS: IFN-γ ELISA showed well-validated results; CMI was not detectable pre-immunization but became detectable post-immunization. Seroconversion was detected in 92.6% of subjects by the immune adherence hemagglutination test; however, half of the subjects did not display an increase in CMI levels. We also compared the incidence of breakthrough varicella and herpes zoster development between CMI post-positive and post-negative vaccinees at 1-2years after the last VZV vaccination. Eight subjects had a history of varicella or herpes zoster exposure post-VZV vaccination. Two of them with post-negative CMI contracted breakthrough varicella 15-16months after the last vaccination, even though they had sufficient VZV-specific antibody levels to be considered seropositive and seroprotected. Conversely, the others with post-positive CMI did not contract breakthrough varicella, despite experiencing extensive VZV exposure through casual contact with playmates and family. CONCLUSIONS: The CMI data generated by this IFN-γ ELISA may accurately reflect real-world immune status, and CMI may be closely related to immunoprotection against breakthrough varicella development.

A recombinant varicella vaccine harboring a respiratory syncytial virus gene induces humoral immunity.

The varicella-zoster virus (VZV) Oka vaccine strain (vOka) is highly efficient and causes few adverse events; therefore, it is used worldwide. We previously constructed recombinant vOka (rvOka) harboring the mumps virus gene. Immunizing guinea pigs with rvOka induced the production of neutralizing antibodies against the mumps virus and VZV. Here, we constructed recombinant vOka viruses containing either the respiratory syncytial virus (RSV) subgroup A fusion glycoprotein (RSV A-F) gene or RSV subgroup B fusion glycoprotein (RSV B-F) gene (rvOka-RSV A-F or rvOka-RSV B-F). Indirect immunofluorescence and Western blot analyses confirmed the expression of each recombinant RSV protein in virus-infected cells. Immunizing guinea pigs with rvOka-RSV A-F or rvOka-RSV B-F led to the induction of antibodies against RSV proteins. These results suggest that the current varicella vaccine genome can be used to generate custom-made vaccine vectors to develop the next generation of live vaccines.

VZV skin-test reaction, but not antibody, is an important predictive factor for postherpetic neuralgia.

BACKGROUND: The decline of cell-mediated immunity (CMI) is thought to be related to the risk of postherpetic neuralgia (PHN) as well as herpes zoster (HZ). However, the relationship between immunological condition and the incidence of PHN is still unclear. OBJECTIVE: We conducted a large-scale prospective cohort study to clarify the relationship between immunological factors for varicella-zoster virus (VZV) and the incidence of PHN. METHODS: We carried out a cohort study on VZV immunity in a population living on an island cluster, Shozu County in Japan, and examined the people who developed HZ during a follow-up period of 3 years, with a focus on the relationship between cell-mediated and humoral immunity and the incidence of PHN. A total of 12,522 people over the age of 50 were enrolled in this study, and 401 registrants were diagnosed with HZ, including 79 PHN cases. We evaluated anatomical location and severity of skin lesion, acute pain severity, presence or absence of abnormal sensations, CMI assessed by VZV skin test, and VZV-specific antibody titer measured by serological tests. RESULTS: The incidence of PHN was significantly associated with a weak response to the VZV skin test, as well as facial or lumbosacral localization of skin rash, severe skin lesion, severe acute pain, and presence of abnormal sensations, but not related to VZV-specific antibody titer. CONCLUSION: The incidence of PHN is significantly associated with the decline of VZV-specific CMI, but not related to VZV-specific humoral immunity.

Varicella zoster virus infection.

Infection with varicella zoster virus (VZV) causes varicella (chickenpox), which can be severe in immunocompromised individuals, infants and adults. Primary infection is followed by latency in ganglionic neurons. During this period, no virus particles are produced and no obvious neuronal damage occurs. Reactivation of the virus leads to virus replication, which causes zoster (shingles) in tissues innervated by the involved neurons, inflammation and cell death - a process that can lead to persistent radicular pain (postherpetic neuralgia). The pathogenesis of postherpetic neuralgia is unknown and it is difficult to treat. Furthermore, other zoster complications can develop, including myelitis, cranial nerve palsies, meningitis, stroke (vasculopathy), retinitis, and gastroenterological infections such as ulcers, pancreatitis and hepatitis. VZV is the only human herpesvirus for which highly effective vaccines are available. After varicella or vaccination, both wild-type and vaccine-type VZV establish latency, and long-term immunity to varicella develops. However, immunity does not protect against reactivation. Thus, two vaccines are used: one to prevent varicella and one to prevent zoster. In this Primer we discuss the pathogenesis, diagnosis, treatment, and prevention of VZV infections, with an emphasis on the molecular events that regulate these diseases. For an illustrated summary of this Primer, visit: http://go.nature.com/14xVI1.

Dextran sulfate-resistant A/Puerto Rico/8/34 influenza virus is associated with the emergence of specific mutations in the neuraminidase glycoprotein.

Dextran sulfate (DS) is a negatively charged sulfated polysaccharide that suppresses the replication of influenza A viruses. The suppression was thought to be associated with inhibition of the hemagglutinin-dependent fusion activity. However, we previously showed that suppression by DS was observed not only at the initial stage of viral infection, but also later when virus is released from infected cells due to inhibition of neuraminidase (NA) activity. In the present study, we isolated DS-resistant A/Puerto Rico/8/34 (PR8) influenza viruses and analyzed the inhibition by DS. We found six mutations in NA genes of five independent resistant PR8 viruses and each resistant NA gene had two mutations. All mutations were from basic to acidic or neutral amino acids. In addition, R430L, K432E or K435E in the 430-435 region was a common mutation in all resistant NA genes. To determine which amino acid(s) are responsible for this resistance, a panel of recombinant viruses containing a PR8 and A/WSN/33(WSN) chimeric NA gene or an NA gene with different mutation(s) was generated using reverse genetics. Using recombinant viruses containing a PR8/WSN chimeric NA, we showed that one third of the C-terminal region of PR8 NA was responsible for DS-sensitivity. Recombinant viruses with a single mutation in NA replicated better than wild-type PR8 in the presence of DS, but were still DS-sensitive. However, replication of recombinant viruses with double mutations from the resistant viruses was not affected by the presence or absence of DS. In addition, resistant recombinant viruses were found to be sensitive to the NA inhibitor, oseltamivir and the oseltamivir-resistant recombinant virus was sensitive to DS. These results suggested that DS is an NA inhibitor with a different mechanism of action from the currently used NA inhibitors and that DS could be used in combination with these inhibitors to treat influenza virus infections.

Intranasal chitosan-DNA vaccines that protect across influenza virus subtypes.

An egg-free and broadly effective influenza vaccine that can be produced rapidly, adequately and cost-effectively is needed. In this study, chitosan-associated DNAs prepared at various nitrogen/phosphate charge (N/P) ratios were studied for their physicochemical properties, stability, cytotoxicity, and protein expression ability. The chitosan-DNA complexes (chitoplexes) of the N/P ratio 2 had the required characteristics including optimal size range, positive surface charge, high DNA association efficiency, tolerability to DNase digestion and mammalian cell viability compatibility. The N/P ratio 2-chitoplexes revealed the highest green fluorescent protein and luciferase expressions in the transfected mammalian cell cultures and in the mouse lungs. Mice immunized intranasally with the N/P ratio 2-chitoplex vaccines carrying DNAs coding for conserved proteins of influenza virus, i.e., ion channel protein (M2) and/or nucleoprotein (NP), had both mucosal and systemic humoral as well as cell mediated immune responses to the in vivo expressed antigens which conferred protection in mice against the lethal challenges not only with the homologous influenza virus subtype (H1N1), but also the heterologous subtype (H3N2). The chitoplexes should be considered as influenza vaccine candidates especially during the period of high vaccine demand. They are suitable for developing areas of the world where conventional vaccine production capacity is lacking.