A correlation of measles specific antibodies and the number of plasmacytoid dendritic cells is observed after measles vaccination in 9 month old infants.

Measles virus (MeV) represents one of the main causes of death among young children, particularly in developing countries. Upon infection, MeV controls both interferon induction (IFN) and the interferon signaling pathway which results in a severe host immunosuppression that can persists for up to 6 mo after infection. Despite the global biology of MeV infection is well studied, the role of the plasmacytoid dendritic cells (pDCs) during the host innate immune response after measles vaccination remains largely uncharacterized. Here we investigated the role of pDCs, the major producers of interferon in response to viral infections, in the development of adaptive immune response against MeV vaccine. We report that there is a strong correlation between pDCs population and the humoral immune response to Edmonston Zagreb (EZ) measles vaccination in 9-month-old mexican infants. Five infants were further evaluated after vaccination, showing a clear increase in pDCs at baseline, one week and 3 months after immunization. Three months postvaccination they showed increase in memory T-cells and pDCs populations, high induction of adaptive immunity and also observed a correlation between pDCs number and the humoral immune response. These findings suggest that the development and magnitude of the adaptive immune response following measles immunization is directly dependent on the number of pDCs of the innate immune response.

Evaluation of safety and immunogenicity of a quadrivalent human papillomavirus vaccine in healthy females between 9 and 26 years of age in Sub-Saharan Africa.

Due to sporadic and not easily accessible cervical cancer screening, human papillomavirus (HPV)-related cervical cancer is a leading cause of cancer death in Sub-Saharan African women. This study was designed to assess the safety and immunogenicity of a quadrivalent human papillomavirus (qHPV) vaccine in sub-Saharan African women. This seven month, double-blind study enrolled 250 healthy, human immunodeficiency virus (HIV)-uninfected females ages 9-26 residing in Ghana, Kenya, and Senegal. Thirty females ages 13-15 and 120 females ages 16-26 received qHPV vaccine. In addition, 100 females ages 9-12 y were randomized in a 4:1 ratio to receive either qHPV vaccine (n = 80) or placebo (n = 20 ). The primary immunogenicity hypothesis was that an acceptable percentage of subjects who received the qHPV vaccine seroconvert to HPV6/11/16/18 at 4 weeks post-dose 3, defined as the lower bound of the corresponding 95% confidence interval (CI) exceeding 90%. The primary safety objective was to demonstrate that qHPV vaccine was generally well tolerated when administered in a 3-dose regimen. The pre-specified statistical criterion for the primary immunogenicity hypothesis was met: the lower bound of the 95% exact binomial CI on the seroconversion rate was at least 98% for each vaccine HPV type and all subjects seroconverted by 4 weeks post-dose 3. Across vaccination groups, the most common adverse events (AE) were at the injection site, including pain, swelling, and erythema. No subject discontinued study medication due to an AE and no serious AEs were reported. There were no deaths. This study demonstrated that qHPV vaccination of sub-Saharan African women was highly immunogenic and generally well tolerated.

A randomized study of the immunogenicity and safety of Japanese encephalitis chimeric virus vaccine (JE-CV) in comparison with SA14-14-2 vaccine in children in the Republic of Korea.

A new live attenuated Japanese encephalitis chimeric virus vaccine (JE-CV) has been developed based on innovative technology to give protection against JE with an improved immunogenicity and safety profile. In this phase 3, observer-blind study, 274 children aged 12-24 months were randomized 1:1 to receive one dose of JE-CV (Group JE-CV) or the SA14-14-2 vaccine currently used to vaccinate against JE in the Republic of Korea (Group SA14-14-2). JE neutralizing antibody titers were assessed using PRNT50 before and 28 days after vaccination. The primary endpoint of non-inferiority of seroconversion rates on D28 was demonstrated in the Per Protocol analysis set as the difference between Group JE-CV and Group SA14-14-2 was 0.9 percentage points (95% confidence interval [CI]: -2.35; 4.68), which was above the required -10%. Seroconversion and seroprotection rates 28 days after administration of a single vaccine dose were 100% in Group JE-CV and 99.1% in Group SA14-14-2; all children except one (Group SA14-14-2) were seroprotected. Geometric mean titers (GMTs) increased in both groups from D0 to D28; GM of titer ratios were slightly higher in Group JE-CV (182 [95% CI: 131; 251]) than Group SA14-14-2 (116 [95% CI: 85.5, 157]). A single dose of JE-CV was well tolerated and no safety concerns were identified. In conclusion, a single dose of JE-CV or SA14-14-2 vaccine elicited a comparable immune response with a good safety profile. Results obtained in healthy Korean children aged 12-24 months vaccinated with JE-CV are consistent with those obtained in previous studies conducted with JE-CV in toddlers.

Correlates of protection for rotavirus vaccines: Possible alternative trial endpoints, opportunities, and challenges.

Rotavirus (RV) is a major vaccine-preventable killer of young children worldwide. Two RV vaccines are globally commercially available and other vaccines are in different stages of development. Due to the absence of a suitable correlate of protection (CoP), all RV vaccine efficacy trials have had clinical endpoints. These trials represent an important challenge since RV vaccines have to be introduced in many different settings, placebo-controlled studies are unethical due to the availability of licensed vaccines, and comparator assessments for new vaccines with clinical endpoints are very large, complex, and expensive to conduct. A CoP as a surrogate endpoint would allow predictions of vaccine efficacy for new RV vaccines and enable a regulatory pathway, contributing to the more rapid development of new RV vaccines. The goal of this review is to summarize experiences from RV natural infection and vaccine studies to evaluate potential CoP for use as surrogate endpoints for assessment of new RV vaccines, and to explore challenges and opportunities in the field.