Immunogenicity of a new gorilla adenovirus vaccine candidate for COVID-19

Mol Ther. 2021 Aug 4;29(8):2412-2423. doi: 10.1016/j.ymthe.2021.04.022. Epub 2021 Apr 23.


The coronavirus disease 2019 (COVID-19) pandemic caused by the emergent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) threatens global public health, and there is an urgent need to develop safe and effective vaccines. Here, we report the generation and the preclinical evaluation of a novel replication-defective gorilla adenovirus-vectored vaccine encoding the pre-fusion stabilized Spike (S) protein of SARS-CoV-2. We show that our vaccine candidate, GRAd-COV2, is highly immunogenic both in mice and macaques, eliciting both functional antibodies that neutralize SARS-CoV-2 infection and block Spike protein binding to the ACE2 receptor, and a robust, T helper (Th)1-dominated cellular response. We show here that the pre-fusion stabilized Spike antigen is superior to the wild type in inducing ACE2-interfering, SARS-CoV-2-neutralizing antibodies. To face the unprecedented need for vaccine manufacturing at a massive scale, different GRAd genome deletions were compared to select the vector backbone showing the highest productivity in stirred tank bioreactors. This preliminary dataset identified GRAd-COV2 as a potential COVID-19 vaccine candidate, supporting the translation of the GRAd-COV2 vaccine in a currently ongoing phase I clinical trial ( NCT04528641).

Keywords: COVID-19; SARS-CoV-2; gorilla adenovirus; immunogenicity; vaccine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / immunology*
  • Adenovirus Vaccines / immunology*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / immunology
  • COVID-19 / immunology*
  • COVID-19 Vaccines / immunology*
  • Cell Line
  • Cell Line, Tumor
  • Female
  • Genetic Vectors / immunology
  • Gorilla gorilla / immunology*
  • Gorilla gorilla / virology
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Immunogenicity, Vaccine / immunology*
  • Macaca
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Middle Aged
  • Pandemics / prevention & control
  • SARS-CoV-2 / immunology*
  • Young Adult


  • Adenovirus Vaccines
  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines

Associated data