Phenotypic and genetic diversity of the traditional Lister smallpox vaccine

As an initial step in the development of a second-generation smallpox vaccine derived from the Lister strain, to be prepared for a variola virus threat, diversity of the traditional vaccine was examined by characterizing a series of ten viral clones.     

The smallpox vaccine induces an early neutralizing IgM response

The antibody response elicited after immunization with vaccinia virus (VacV) is known to be sufficient to confer host protection against VacV or smallpox. In humans it has been shown that such anti-VacV antibody production can be sustained for decades. Nevertheless, little is known about the kinetics and the role in protection of the early antibody response after vaccination. In this study we identify VacV neutralizing IgM antibodies as early as 4 days after infection of C57BL/6 mice. Most of this IgM production is T cell dependent and predominantly independent of the germinal center reaction (SAP/SH2D1A independent). Importantly, the IgM neutralized both infectious forms of VacV: the intracellular mature virion (MV, IMV) and the extracellular enveloped virion (EV, EEV). Moreover, in mice primed with MHCII restricted peptides, an increase in the total VacV neutralizing antibody titers was seen, a large component of which was neutralizing IgM against the same protein from which the priming peptide was derived. To further demonstrate the biological relevance of this early neutralizing response, we examined anti-VacV antibodies in humans after vaccination. Human subjects could be divided into two groups early after immunization: IgG^hi and IgG^lo. VacV IgM neutralizing antibodies were detected in the IgG^lo group. Taken together these results indicate that both in a small animal model and in humans an early neutralizing IgM response after VacV immunization is present and likely contributes to control of the infection prior to the development of a robust IgG response.     

埃博拉出血热的研究进展

埃博拉病毒(ebola virus,EBOV)是传染性疾病埃博拉出血热(ebola hemorrhagic fever,EBHF)的病原体,已在非洲造成多次大规模的暴发流行,死亡率极高。它可通过与患者体液直接接触,或与患者擦伤的皮肤、暴露的黏膜等接触而传染。典型症状及体征主要表现为常规的发热、乏力、肌肉酸痛、头痛、咽喉痛、结膜出血和休克,随后出现呕吐、腹泻、皮疹及多器官功能衰竭等。其致病机制与病毒包膜糖蛋白(viral envelope glycoprotein,GP)有密切的关系。现已制造出使猴群不会被埃博拉病毒感染的疫苗,但尚无对人类有效的疫苗。     

Protective immune responses induced by different recombinant vaccine regimes to Rift Valley fever

The glycoprotein (GP) and nucleocapsid (NC) genes of Rift Valley fever virus (RVFV) were expressed in different expression systems and were evaluated for their ability to protect mice from virulent challenge using a prime-boost regime. Mice vaccinated with a lumpy skin disease virus-vectored recombinant vaccine (rLSDV-RVFV) expressing the two RVFV glycoproteins (G1 and G2) developed neutralising antibodies and were fully protected when challenged, as were those vaccinated with a crude extract of truncated G2 glycoprotein (tG2). By contrast mice vaccinated with a DNA vaccine expressing G1 and G2 did not sero-convert with only 20% of them surviving challenge. Mice vaccinated with the DNA vaccine and boosted with rLSDV-RVFV also failed to sero-convert but 40% survived challenge. Surprisingly, although none of the mice immunised with the purified NC protein sero-converted, 60% of them survived virulent challenge. The rLSDV-RVFV construct was then further evaluated in sheep for its dual protective abilities against RVFV and sheeppox virus (SPV). Vaccinated sheep sero-converted for both viruses and were protected against RVFV challenge, however, neither the immunised or negative control animals showed any significant reactions to the virulent SPV challenge.     

New vaccines against hepatitis B

The high cost and limited availability of the plasma-derived hepatitis B vaccines have prevented their widespread use, especially in the less developed areas where they are needed most. Hepatitis B vaccines produced by recombinant technology seem to offer a solution to these difficulties. Studies reported up to now confirmed the safety of this vaccine. Immunogenicity studies in various population groups showed that seroconversion rates and antibody titres are comparable to plasma vaccine. In assessing the efficacy of the vaccine, information concerning the quality of the anti-HBs induced should complement these data. Potential live vaccines using recombinant vaccinia viruses have been constructed for hepatitis .B. Preliminary studies in rabbits and chimpanzees indicated the feasibility of future using a recombinant vaccinia virus.Chemically synthesized polypeptides corresponding to relevant epitopes of HBsAg may be useful as synthetic vaccines offering the advantages of a cheap viral immunogen free from irrelevant antigenic determinants.Finally preliminary studies for an idiotypic vaccine have already been reported.     

Development of an attenuated smallpox vaccine candidate: The KVAC103 strain

Smallpox, a disease caused by the variola virus, is one of the most dangerous diseases and had killed numerous people before it was eradicated in 1980. However, smallpox has emerged as the most threatening bio-terrorism agent; as the first- and second-generation smallpox vaccines have been controversial and have caused severe adverse reactions, new demands for safe smallpox vaccines have been raised and some attenuated smallpox vaccines have been developed. We have developed a cell culture-based highly attenuated third-generation smallpox vaccine candidate KVAC103 strain by 103 serial passages of the Lancy-Vaxina strain derived from the Lister in Vero cells. Several clones were selected, taking into consideration their shape, size, and growth rate in mammalian cells. The clones were then inoculated intracerebrally in suckling mice to test for neurovirulence by observing survival. Protective immune responses in adult mice were examined by measuring the levels of neutralization antibodies and IFN-γ expression. Among several clones, clone 7 was considered the best alternative candidate because there was no mortality in suckling mice against a lethal challenge. In addition, enhanced neutralizing antibodies and T-cell mediated IFN-γ production were observed in clone 7-immunized mice. Clone 7 was named “KVAC103” and was used for the skin toxicity test and full-genome analysis. KVAC103-inoculated rabbits showed reduced skin lesions compared to those inoculated with the Lister strain, Lancy-Vaxina. A whole genome analysis of KVAC103 revealed two major deleted regions that might contribute to the reduced virulence of KVAC103 compared to the Lister strain. Phylogenetic inference supported the close relationship with the Lister strain. Collectively, our data demonstrate that KVAC103 holds promise for use as a third-generation smallpox vaccine strain due to its enhanced safety and efficacy.     

Genome-wide association study of antibody response to smallpox vaccine

We performed a genome-wide association study (GWAS) of antibody levels in a multi-ethnic group of 1071 healthy smallpox vaccine recipients. In Caucasians, the most prominent association was found with promoter SNP rs10489759 in the LOC647132 pseudogene on chromosome 1 (p=7.77×10(-8)). In African-Americans, we identified eight genetic loci at p<5×10(-7). The SNP association with the lowest p-value (rs10508727, p=1.05×10(-10)) was in the Mohawk homeobox (MKX) gene on chromosome 10. Other candidate genes included LOC388460, GPR158, ZHX2, SPIRE1, GREM2, CSMD1, and RUNX1. In Hispanics, the top six associations between genetic variants and antibody levels had p-values less than 5×10(-7), with p=1.78×10(-10) for the strongest statistical association (promoter SNP rs12256830 in the PCDH15 gene). In addition, SNP rs4748153 in the immune response gene PRKCQ (protein kinase C, theta) was significantly associated with neutralizing antibody levels (p=2.51×10(-8)). Additional SNP associations in Hispanics (p≤3.40×10(-7)) were mapped to the KIF6/LOC100131899, CYP2C9, and ANKLE2/GOLGA3 genes. This study has identified candidate SNPs that may be important in regulating humoral immunity to smallpox vaccination. Replication studies, as well as studies elucidating the functional consequences of contributing genes and polymorphisms, are underway.     

Transcription of immune genes upon challenge with viral hemorrhagic septicemia virus (VHSV) in DNA vaccinated rainbow trout (Oncorhynchus mykiss)

Even though DNA vaccination has proven as one of the most effective methods in controlling fish rhabdoviruses, the immune mechanisms responsible for protection are still unknown. Many studies have focused on studying which cytokines and immune genes are triggered in response to the vaccine at different times post-vaccination. However, to elucidate the mechanism(s) responsible for protection, to our understanding it is also of great relevance to study the immune response to the virus in fish that have been previously vaccinated and compare it to the effects that the virus might have on non-vaccinated fish. This type of study has never been performed to date in fish. Thus, in the current work, we vaccinated rainbow trout (Oncorhynchus mykiss) with a DNA vaccine against viral hemorrhagic septicemia virus (VHSV), and 30 days post-vaccination we challenged the fish with a virulent VHSV. It was then, that we studied the immune response to the virus at very early times post-infection in fish, in order to compare the effects of VHSV on vaccinated or non-vaccinated trout. We studied the levels of expression of interleukin 1beta (IL-1beta), major histocompatibility complex (MHC) class Ialpha and IIalpha genes, immunoglobulin M (IgM), CD8alpha, type I interferon (IFN), Mx, IFN-gamma and natural killer enhancing factor (NKEF) in head kidney, spleen and blood. When we compared the effect that VHSV had on vaccinated fish to the effect that the virus produced in fish vaccinated with the empty plasmid, the genes that were significantly up-regulated were IL-1beta and MHC IIalpha in the spleen at day 1 post-infection, MHC Ialpha in all organs at day 1 post-infection, and IFN and Mx in the spleen and blood at days 1 and 3 post-infection, respectively. Genes that correlate with an increased specific immune response were not significantly increased in response to VHSV in these vaccinated animals. The results suggest that DNA vaccination induces a memory state in fish that, on the contrary to what would occur in mammals, primes the non-specific immune responses upon a later encounter with the virus.     

Immunogenicity and safety of an inactivated Rift Valley fever vaccine in a 19-year study

An investigational, formalin-inactivated Rift Valley fever (RVF) vaccine, known as The Salk Institute-Government Services Division (TSI-GSD) 200 vaccine, was administered to 1860 at-risk subjects (5954 doses) between 1986 and 2004 as a three-dose primary series (days 0, 7, and 28) followed by booster doses as needed for declining titers. An initial positive serological response (PRNT₈₀ ≥ 1:40) to the primary series was observed in 90% of subjects. Estimate of the PRNT₈₀ response half-life in initial responders to the primary series by Kaplan-Meier plot was 315 days after the primary series dose 3. Differences in a serological response were observed at 2 weeks after dose 3 of the primary series between vaccine lots and for gender (women > men); a trend was observed for age (<40 years). When response to the primary series was measured by PRNT₅₀ titer ≥1:40, nearly all subjects (99.1%) responded. In individuals not initially responding to the primary series (PRNT₈₀ < 1:40), a response was observed in most subjects after receiving only one booster dose. Immune response (all subjects) to subsequent booster doses for a declining titer (PRNT₈₀ < 1:40) was 98.4%. The vaccine was well-tolerated; vaccine-related adverse reactions were generally mild and self-limited. Differences in adverse events were observed with vaccine lot and sex. The data support the safety and immunogenicity of the inactivated RVF vaccine, and may serve as a standard of comparison for immunogenicity and safety for future RVF vaccines.     

流行性出血热三种单价灭活疫苗免疫后第5年预防效果

目的 观察流行性出血热（ｅｐｉｄｅｍｉｃ ｈｅｍｏｒｒｈａｇｉｃ ｆｅｖｅｒ,ＥＨＦ）沙鼠肾细胞Ｉ型灭活疫苗（沙鼠苗）免疫后第５年、乳鼠脑纯化Ｉ型灭活疫苗（鼠脑苗）免疫后第４年和地鼠肾细胞Ⅱ型灭活疫苗（地鼠苗）免疫后第５年在ＥＦＨ疫区试验人群中的安全性、血清学效果和预防效果。方法 现场试验人群采用整群随机分组,分为疫苗接种组和对照组。实验室血清标本检测采用间接免疫荧光法（ＩＦＡＴ）、微量细胞病变中     

肾综合征出血热抗病毒治疗及疫苗研发进展

肾综合征出血热（hemorrhagic fever with renal syndrome, HFRS）是由汉坦病毒感染引起的一种自然疫源性疾病,在世界范围内广泛流行,我国一直是流行高发区,患者占所有HFRS患者一半以上,其主要临床特征为发热、出血、低血压休克和肾脏损害,严重危害人类健康。尽管抗病毒治疗和疫苗免疫接种可以防治汉坦病毒感染,但目前尚无特效抗病毒药物。近年来,随着医学科技进步,汉坦病毒的抗病毒治疗和疫苗研发有了新的进展。本文基于近年体内外研究及临床试验结果,对HFRS抗病毒治疗和疫苗研发进展作一综述。     

A protein-based smallpox vaccine protects non-human primates from a lethal monkeypox virus challenge

Concerns about infections caused by orthopoxviruses, such as variola and monkeypox viruses, drive ongoing efforts to develop novel smallpox vaccines that are both effective and safe to use in diverse populations. A subunit smallpox vaccine comprising vaccinia virus membrane proteins A33, B5, L1, A27 and aluminum hydroxide (alum) ± CpG was administered to non-human primates, which were subsequently challenged with a lethal intravenous dose of monkeypox virus. Alum adjuvanted vaccines provided only partial protection but the addition of CpG provided full protection that was associated with a more homogeneous antibody response and stronger IgG1 responses. These results indicate that it is feasible to develop a highly effective subunit vaccine against orthopoxvirus infections as a safer alternative to live vaccinia virus vaccination.     

Seroprevalence of Alkhurma and other hemorrhagic fever viruses, Saudi Arabia

A 2009 deployment of military units from several Saudi Arabian provinces to Jazan Province, Saudi Arabia, enabled us to evaluate exposure to Alkhurma, Crimean-Congo, dengue, and Rift Valley hemorrhagic fever viruses. Seroprevalence to all viruses was low; however, Alkhurma virus seroprevalence was higher (1.3%) and less geographically restricted than previously thought.     

Sex difference in immune response to vaccination: A participant-level meta-analysis of randomized trials of IMVAMUNE® smallpox vaccine

IntroductionPrevious research shows immune response to vaccination differs by sex but this has not been explored for IMVAMUNE^®, a replication-deficient smallpox vaccine developed in response to the potential for bioterrorism using smallpox.MethodsWe conducted a participant-level meta-analysis (N = 275, 136 men, 139 women) of 3 randomized trials of IMVAMUNE conducted at 13 centers in the US through a federally-funded extramural research program. Studies were eligible for inclusion if they tested the standard dose (1 × 10⁸ TCID₅₀/mL on Days 0 and 28) of liquid formulation IMVAMUNE, were completed at the time of our search, and enrolled healthy vaccinia-naïve participants. Models of the peak log₂ ELISA and PRNT titers post-second vaccination were constructed for each study with sex as a covariate. Results from these models were combined into random effects meta-analyses of the sex difference in response to IMVAMUNE. We then compared this approach with fixed effects models using the combined participant level data.ResultsIn each study the mean peak log₂ ELISA titer was higher in men than women but no single study demonstrated a statistically significant difference. Combination of the adjusted study-specific estimates into the random effects model showed a higher mean peak log₂-titer in men compared with women (absolute difference [men–women]: 0.32, 95% CI: 0.02–0.60). Fixed effects models controlling for study showed a similar result (log₂ ELISA titer, men–women: 0.34, 95% CI: 0.04–0.63). This equates to a geometric mean peak titer that is approximately 27% higher in men than women (95% CI: 3–55%). Peak log₂ PRNT titers were also higher (although not significantly) in men (men–women: 0.14, 95% CI: −0.30 to 0.58).ConclusionOur results show statistically significant differences in response to IMVAMUNE comparing healthy, vaccinia-naïve men with women and suggest that sex should be considered in further development and deployment of IMVAMUNE and other MVA-based vaccines.     

Immunogenicity and protective efficacy of recombinant Modified Vaccinia virus Ankara candidate vaccines delivering West Nile virus envelope antigens

West Nile virus (WNV) cycles between insects and wild birds, and is transmitted via mosquito vectors to horses and humans, potentially causing severe neuroinvasive disease. Modified Vaccinia virus Ankara (MVA) is an advanced viral vector for developing new recombinant vaccines against infectious diseases and cancer. Here, we generated and evaluated recombinant MVA candidate vaccines that deliver WNV envelope (E) antigens and fulfil all the requirements to proceed to clinical testing in humans. Infections of human and equine cell cultures with recombinant MVA demonstrated efficient synthesis and secretion of WNV envelope proteins in mammalian cells non-permissive for MVA replication. Prime-boost immunizations in BALB/c mice readily induced circulating serum antibodies binding to recombinant WNV E protein and neutralizing WNV in tissue culture infections. Vaccinations in HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-knockout mice elicited WNV E-specific CD8+ T cell responses. Moreover, the MVA–WNV candidate vaccines protected C57BL/6 mice against lineage 1 and lineage 2 WNV infection and induced heterologous neutralizing antibodies. Thus, further studies are warranted to evaluate these recombinant MVA–WNV vaccines in other preclinical models and use them as candidate vaccine in humans.     

Long-term efficacy of plasma-derived and recombinant hepatitis B vaccines in a rural township of Central Taiwan

Aims

To assess the differences of long-term efficacy between plasma-derived and recombinant hepatitis B virus (HBV) vaccines and the effectiveness of catch-up vaccination in adolescents with undetectable anti-HBs.

Methods

Before 1992, infants born in Taiwan were immunized using plasma-derived HB vaccine, and thereafter, by using recombinant HB vaccine. From the only junior middle school of a rural township in central–southern Taiwan, 1788 (93.7%) students from five cross-sectional screenings, grouping into three birth cohorts (Group I: born during 1984–1986, II: 1986–1992 and III: 1992–1995), were enrolled for checking HBsAg, anti-HBs and anti-HBc. Students with undetectable HBsAg and anti-HBs underwent a booster dose (2.5 ug) of recombinant HB vaccine (Engerix-B; GlaxoSmithKline, Rixensart, Belgium) and had anti-HBs re-checked 3 weeks later. Individuals who had remained undetectable for anti-HBs completed the other two doses of HB vaccines at 1 and 6 months later.

Results

The prevalence of HBsAg (11.4, 5.4 and 1.2%), anti-HBs (64.5, 44.1 and 36.0%) and anti-HBc (29.5, 12.5 and 4.4%) decreased from Group I to III (P < 0.001 for trends). After a booster dose, the positive rates of anti-HBs increased up to 80.5% (16% increase) in Group I, 81.0% (36.9% increase) in Group II, and 94.4% (58.4% increase) in Group III. The percentages of anamnestic response increased with a trend (P < 0.001). A total of 110 non-responders completed 3 doses of catch-up HB vaccination, but 3 cases (2.7%) of Group II, evoked primary vaccination response.

Conclusion

Recombinant vaccine showed predominant disappearance rate (62.7%) of anti-HBs 12–15 years after vaccination, but provided better anamnestic response after a booster dose. It also showed high success rate (97.3%) in catch-up vaccination in adolescents.     

一起流行性出血热疫苗接种人员发病事件的应急调查

目的 分析江西省某县流行性出血热疫苗接种人员发病的原因,为今后类似事件的调查提供经验与借鉴。方法 回顾性收集4例疑似病例的流行病学调查资料和疫苗接种资料,应用胶体金法和ELISA法对病例血清标本进行汉坦病毒IgM/IgG抗体检测。结果 4例疑似病例均有流行性出血热疫苗接种史。病例1和病例4有发热、“三红”、“三痛”、水肿和尿蛋白阳性等出血热相关的症状,病例1汉坦病毒IgG抗体检测阳性,病例4的IgM和IgG阳性,病例2和病例3无出血热相关的典型症状,汉坦病毒IgM/IgG抗体检测阴性。依据流行性出血热诊断标准综合研判,病例1和病例4被确诊为流行性出血热病例,病例2和病例3排除流行性出血热。结论 该起事件共发现2例流行性出血热确诊病例,2例误诊病例。建议加强医疗机构对出血热诊治知识的培训,提高医疗机构出血热的实验室诊断率,提升医疗机构流行性出血热病例的早发现和早诊断能力。     

Impaired innate,humoral, and cellular immunity despite a take in smallpox vaccine recipients

Smallpox vaccine is highly effective, inducing protective immunity to smallpox and diseases caused by related orthopoxviruses. Smallpox vaccine efficacy was historically defined by the appearance of a lesion or “take” at the vaccine site, which leaves behind a characteristic scar. Both the take and scar are readily recognizable and were used during the eradication effort to indicate successful vaccination and to categorize individuals as “protected.” However, the development of a typical vaccine take may not equate to the successful development of a robust, protective immune response. In this report, we examined two large (>1000) cohorts of recipients of either Dryvax^® or ACAM2000 using a testing and replication study design and identified subgroups of individuals who had documented vaccine takes, but who failed to develop robust neutralizing antibody titers. Examination of these individuals revealed that they had suboptimal cellular immune responses as well. Further testing indicated these low responders had a diminished innate antiviral gene expression pattern (IFNA1, CXCL10, CXCL11, OASL) upon in vitro stimulation with vaccinia virus, perhaps indicative of a dysregulated innate response. Our results suggest that poor activation of innate antiviral pathways may result in suboptimal immune responses to the smallpox vaccine. These genes and pathways may serve as suitable targets for adjuvants in new attenuated smallpox vaccines and/or effective antiviral therapy targets against poxvirus infections.