T-cell-dependent mechanisms promote Ebola VLP-induced antibody responses, but are dispensable for vaccine-mediated protection

Emerg Microbes Infect. 2017 Jun 7;6(6):e46. doi: 10.1038/emi.2017.31.

Abstract

Humoral responses are essential for the protective efficacy of most Ebola virus (EBOV) candidate vaccines; however, the in vivo development of protective anti-EBOV B-cell responses is poorly defined. Here, by using the virus-like particle (VLP) as a model antigen, we demonstrate that humoral responses are generated through follicular B-cell and T-cell-dependent mechanisms in a mouse model of EBOV infection. In addition, we show that the inclusion of the clinical-grade dsRNA adjuvant known as poly-ICLC in VLP vaccinations both augments and sustains germinal center B-cell reactions, antigen-specific B-cell frequencies and anti-EBOV serum titers. Finally, we used mice that were deficient in either B-cells or T-cell-dependent antibody production to distinguish the contributing roles of EBOV humoral responses. We demonstrate that while anti-EBOV antibody responses promote protection, VLP-vaccinated mice can survive EBOV infection in the absence of detectable anti-EBOV antibodies. Moreover, we found that adjuvant signaling could circumvent the complete requirement for B-cell immunity in protection against EBOV. Collectively, these studies may prove valuable for the characterization and future development of additional EBOV vaccine candidates.

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Animals
  • Antibodies, Viral / blood*
  • Antibodies, Viral / immunology
  • B-Lymphocytes / immunology
  • Disease Models, Animal
  • Ebola Vaccines / administration & dosage
  • Ebola Vaccines / immunology*
  • Ebolavirus / immunology*
  • Germinal Center / immunology
  • Hemorrhagic Fever, Ebola / immunology
  • Hemorrhagic Fever, Ebola / prevention & control*
  • Mice
  • RNA, Double-Stranded / immunology
  • T-Lymphocytes / immunology*
  • Vaccines, Virus-Like Particle / immunology*

Substances

  • Adjuvants, Immunologic
  • Antibodies, Viral
  • Ebola Vaccines
  • RNA, Double-Stranded
  • Vaccines, Virus-Like Particle