Ebola hemorrhagic fever, also known as Ebola virus disease or EVD, is one of the most dangerous viral diseases in humans and animals. In this open-label, dose-escalation clinical trial, we assessed the safety, side effects, and immunogenicity of a novel, heterologous prime-boost vaccine against Ebola, which was administered in 2 doses to 84 healthy adults of both sexes between 18 and 55 years. The vaccine consists of live-attenuated recombinant vesicular stomatitis virus (VSV) and adenovirus serotype-5 (Ad5) expressing Ebola envelope glycoprotein. The most common adverse event was pain at the injection site, although no serious adverse events were reported. The vaccine did not significantly impact blood, urine, and immune indices. Seroconversion rate was 100 %. Antigen-specific IgG geometric mean titer at day 42 was 3,277 (95 % confidence interval 2,401–4,473) in volunteers immunized at full dose. Neutralizing antibodies were detected in 93.1 % of volunteers immunized at full dose, with geometric mean titer 20. Antigen-specific response in peripheral blood mononuclear cells was also detected in 100 % of participants, as well as in CD4+ and CD8+ T cells in 82.8 % and 58.6 % of participants vaccinated at full dose, respectively. The data indicate that the vaccine is safe and induces strong humoral and cellular immune response in up to 100 % of healthy adult volunteers, and provide a rationale for testing efficacy in Phase III trials. Indeed, the strong immune response to the vaccine may elicit long-term protection. This trial was registered with grls.rosminzdrav.ru (No. 495*), and with zakupki.gov.ru (No. 0373100043215000055).

Binding of pattern recognition receptors (PRRs) by pathogen-associated molecular patterns (PAMPs) activates innate immune responses and contributes to development of adaptive immunity. Simultaneous stimulation of different types of PRRs can have synergistic immunostimulatory effects resulting in enhanced production of molecules that mediate innate immunity such as inflammatory cytokines, antimicrobial peptides, etc. Here, we evaluated the impact of combined stimulation of PRRs from different families on adaptive immunity by generating alum-based vaccine formulations with ovalbumin as a model antigen and the Toll-like receptor 4 (TLR4) agonist MPLA and the Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) agonist MDP adsorbed individually or together on the alum-ovalbumin particles. Multiple in vitro and in vivo readouts of immune system activation all showed that while individual PRR agonists increased the immunogenicity of vaccines compared to alum alone, the combination of both PRR agonists was significantly more effective. Combined stimulation of TLR4 and NOD2 results in a stronger and broader transcriptional response in THP-1 cells compared to individual PRR stimulation. Immunostimulatory composition containing both PRR agonists (MPLA and MDP) in the context of the alum-based ovalbumin vaccine also enhanced uptake of vaccine particles by bone marrow derived dendritic cells (BMDCs) and promoted maturation (up-regulation of expression of CD80, CD86, MHCII) and activation (production of cytokines) of BMDCs. Finally, immunization of mice with vaccine particles containing both PRR agonists resulted in enhanced cellular immunity as indicated by increased proliferation and activation (IFN-γ production) of splenic CD4+ and CD8+ T cells following in vitro restimulation with ovalbumin and enhanced humoral immunity as indicated by higher titers of ovalbumin-specific IgG antibodies. These results indicate that combined stimulation of TLR4 and NOD2 receptors dramatically enhances activation of both the humoral and cellular branches of adaptive immunity and suggests that inclusion of agonists of these receptors in standard alum-based adjuvants could be used to improve the effectiveness of vaccination.

Common marmosets are small New World primates that have been increasingly used in biomedical research. This report presents efficient protocols for assessment of the parameters of adaptive cell-mediated immunity in common marmosets, including the major subpopulations of lymphocytes and main markers of T- and B-cell maturation and activation using flow cytometry with a multicolor panel of fluorescently labelled antibodies. Blood samples from eight common marmosets were stained with fluorescently labeled monoclonal antibodies against their population markers (CD45, CD3, CD20, CD4, CD8) and lymphocyte maturation and activation markers (CD69, CD62L, CD45RO, CD107a and CD27) and analyzed by flow cytometry. Within the CD45+ population, 22.75.5% cells were CD3- CD20+ and 67.66.3% were CD3+CD20-. The CD3+ subpopulation included 55.75.5% CD3+CD4+CD8- and 34.33.7% CD3+CD4-CD8+ cells. Activation and maturation markers were expressed in the following lymphocyte proportions: CD62L on 54.010.7% of CD3+CD4+ cells and 74.412.1% of CD3+CD8+ cells; CD69 on 2.71.2% of CD3+CD4+ cells and 1.20.5% of CD3+CD8+ cells; CD45RO on 1.60.6% of CD3+CD4+ cells and 1.80.7% of CD3+CD8+ cells; CD107a on 0.70.5% of CD3+CD4+ cells and 0.50.3% of CD3+CD8+ cells; CD27 on 94.62.1% of CD3+ cells and 8.93.9% CD20+ cells. Female and male subjects differed in the percentage of CD3+CD4+CD45RO+ cells (1.90.5 in females vs 1.10.2 in males; p 0.05). The percentage of CD20+CD27+ cells was found to highly correlate with animals age (r = 0.923, p 0.005). The basal parameters of adaptive cell-mediated immunity in nave healthy marmosets without markers of systemic immune activation were obtained. These parameters and the described procedures are crucial in documenting the changes induced in common marmosets by prophylactic and therapeutic immune interventions.

Болезнь, вызванная вирусом Эбола (БВВЭ) — одно из самых высоколетальных вирусных заболеваний, поражающих человека и приматов. Возбудителем БВВЭ является вирус Эбола. В настоящее время известно шесть видов этого вируса, три из них патогенны для человека — это виды Заир (ZEBOV), Судан (SUDV) и Бундибугио (BDBV), вызывающие острые вирусные высоконтагиозные лихорадки у людей и приматов с летальностью до 90%. В большинстве случаев БВВЭ вызвана видом ZEBOV. Разработка вакцин против БВВЭ началась сразу после идентификации возбудителя в 1976 г. На сегодняшний день в мире зарегистрировано четыре вакцинных препарата для профилактики БВВЭ. Все они основаны на протективном антигене — гликопротеине (GP) вируса Эбола вида ZEBOV. В силу того, что виды SUDV и BDBV также могут быть причиной вспышек и эпидемий БВВЭ, очевидна необходимость разработки вакцин, способных обеспечить защиту от всех известных патогенных для человека видов вируса Эбола. В статье систематизированы данные относительно структуры, иммуногенных и протективных свойств GP вируса Эбола, проведен анализ иммунодоминантных эпитопов гликопротеина вирусов ZEBOV, SUDV и BDBV, необходимых для формирования протективного иммунитета, а также предложен рациональный, на наш взгляд, подход создания возможных вариантов вакцин против БВВЭ, вызванной разными видами вируса Эбола, состоящий в использовании векторных конструкций, экспрессирующих как минимум два варианта гликопротеина — GP вируса Эбола вида ZEBOV и вида SUDV.