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Immunization against Hepatitis E.

ABSTRACT: Soon after the 1991 molecular cloning of hepatitis E virus (HEV), recombinant viral capsid antigens were expressed and tested in nonhuman primates for protection against liver disease and infection. Two genotype 1 subunit vaccine candidates entered clinical development: a 56 kDA vaccine expressed in insect cells and HEV 239 vaccine expressed in Escherichia coli Both were highly protective against hepatitis E and acceptably safe. The HEV 239 vaccine was approved in China in 2011, but it is not yet prequalified by the World Health Organization, a necessary step for introduction into those low- and middle-income countries where the disease burden is highest. Nevertheless, the stage is set for the final act in the hepatitis E vaccine story-policymaking, advocacy, and pilot introduction of vaccine in at-risk populations, in which it is expected to be cost-effective.

SUBMITTER: Innis BL

PROVIDER: S-EPMC6211382 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Immunization against Hepatitis E.

Innis Bruce L BL Lynch Julia A JA

Cold Spring Harbor perspectives in medicine 20181101 11

Soon after the 1991 molecular cloning of hepatitis E virus (HEV), recombinant viral capsid antigens were expressed and tested in nonhuman primates for protection against liver disease and infection. Two genotype 1 subunit vaccine candidates entered clinical development: a 56 kDA vaccine expressed in insect cells and HEV 239 vaccine expressed in <i>Escherichia coli</i> Both were highly protective against hepatitis E and acceptably safe. The HEV 239 vaccine was approved in China in 2011, but it is ...[more]

PMID: 29530951

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Project description:IntroductionThe continually increasing incidence of hepatitis, a worldwide health issue, in Pakistan, has highlighted the need to investigate the epidemiology factors and implement preventive measures accordingly. The purpose of this study was to scrutinize the prevalent and significantly associated risk factors of hepatitis in students and employees, screening them for hepatitis B and C virus and vaccinating them against HBV to make IUB hepatitis free.MethodologyA total of 12,912 participants including students (n = 10,948) and employees (n = 1964) were screened for HBV and HCV via immunochromatographic test. Hepatitis- positive participants' blood samples were further tested and viral load was estimated by quantitative PCR. All the hepatitis-negative participants were vaccinated against HBV. The demographic and risk factors-related data were collected using the questionnaire. Statistical analysis (Chi-square test and bivariate regression analysis) was performed using SPSS software to explore any association between risk factors and hepatitis.ResultsResults indicated that 662/12912 participants (students = 478/10,948, employees = 184/1,964) tested positive for hepatitis. Among them, HCV was observed to be more prevalent than HBV among the study participants, employees, and students, and viral count was low in both HBV and HCV-infected participants. However, men were more affected than women. The studied risk factors represented higher frequency among hepatitis-positive participants relative to the hepatitis-negative participants. The Chi-square test revealed that students' gender, history of hepatitis in the family and relatives, dental treatment, sharing cosmetics and shaving blades were significant (p > 0.005) risk factors of hepatitis while in the employees group surgery and age were significant. Moreover, the reused of syringes was found to be associated with hepatitis in both groups. The bivariate analysis helped to identify various new risk factors which were independently, either positively or negatively, associated with hepatitis.DiscussionOur study enabled us to recognize different risk factors of hepatitis among the target population. The information thus generated can be usefully applied in planning hepatitis awareness, targeted screening, and effective control programs for other target populations. In general, this module can be further utilized for any other disease.

Project description:Chikungunya virus (CHIKV) is a reemerging mosquito-borne alphavirus that causes debilitating arthralgia in humans. Here we describe the development and testing of novel DNA replicon and protein CHIKV vaccine candidates and evaluate their abilities to induce antigen-specific immune responses against CHIKV. We also describe homologous and heterologous prime-boost immunization strategies using novel and previously developed CHIKV vaccine candidates. Immunogenicity and efficacy were studied in a mouse model of CHIKV infection and showed that the DNA replicon and protein antigen were potent vaccine candidates, particularly when used for priming and boosting, respectively. Several prime-boost immunization strategies eliciting unmatched humoral and cellular immune responses were identified. Further characterization by antibody epitope mapping revealed differences in the qualitative immune responses induced by the different vaccine candidates and immunization strategies. Most vaccine modalities resulted in complete protection against wild-type CHIKV infection; however, we did identify circumstances under which certain immunization regimens may lead to enhancement of inflammation upon challenge. These results should help guide the design of CHIKV vaccine studies and will form the basis for further preclinical and clinical evaluation of these vaccine candidates.As of today, there is no licensed vaccine to prevent CHIKV infection. In considering potential new vaccine candidates, a vaccine that could raise long-term protective immunity after a single immunization would be preferable. While humoral immunity seems to be central for protection against CHIKV infection, we do not yet fully understand the correlates of protection. Therefore, in the absence of a functional vaccine, there is a need to evaluate a number of different candidates, assessing their merits when they are used either in a single immunization or in a homologous or heterologous prime-boost modality. Here we show that while single immunization with various vaccine candidates results in potent responses, combined approaches significantly enhance responses, suggesting that such approaches need to be considered in the further development of an efficacious CHIKV vaccine.

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Immunization against Hepatitis E.

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Immunization against Hepatitis E.

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