Single-Shot ChAd3-MARV Vaccine in Modified Formulation Buffer Shows 100% Protection of NHPs

Area of Science:

• Virology
• Vaccinology
• Immunology

Background:

• Marburg virus disease (MVD) poses significant global health and national security risks due to its high case fatality rate (24-88%).
• No prophylactic vaccine for MVD is currently approved, highlighting an urgent need for effective prevention strategies.
• The chimpanzee adenovirus type 3 (ChAd3) vector platform has shown prior success against related filoviruses and Marburg virus itself.

Purpose of the Study:

• To evaluate the efficacy of a replication-defective ChAd3-vectored Marburg virus Angola glycoprotein (GP)-expressing vaccine against lethal Marburg virus challenge in a macaque model.
• To assess the immunogenicity and protective capabilities of a new clinical formulation of the ChAd3-MARV vaccine.

Main Methods:

• Macaques were vaccinated with a single dose of the ChAd3-MARV vaccine (1 × 10¹¹ virus particles) in a novel clinical formulation.
• Vaccinated macaques and a control group were subsequently challenged with lethal Marburg virus Angola.
• Survival rates and the production of Marburg virus GP-specific IgGs were monitored.
• A qualified anti-GP Marburg virus IgG ELISA was developed and validated.

Main Results:

• The ChAd3-MARV vaccine conferred 100% protection against lethal Marburg virus Angola challenge in macaques.
• Control animals exhibited 0% survival, underscoring the vaccine's efficacy.
• Vaccination induced the production of Marburg virus GP-specific IgGs.
• The results were reproducible across different formulations and laboratories.

Conclusions:

• A single dose of the ChAd3-MARV vaccine provides robust and reproducible protection against Marburg virus challenge.
• The vaccine's efficacy, coupled with the development of a qualified diagnostic assay, supports its advancement towards clinical use for Marburg virus disease prevention.