Towards the spanish vaccine against SARS-CoV-2, responsible for the pandemic Covid-19

Abstract

There is a general consensus that the only way to stop the pandemic caused by the coronavirus SARS-CoV-2 is through the development of an effective and safe vaccine. Various countries have move forward to develop a vaccine, and currently a number of preclinical and clinical trials phase I/II revealed that some of the vaccines triggered activation of humoral and cellular immune responses that could be relevant in protection against the coronavirus, but it remains yet to demonstrated efficacy in the population of any of the vaccines. Our group of Poxvirus and Vaccines at the CNB-CSIC started with the development of a vaccine immediately after the full genome (30.000 nucleotides) sequence of the SARS-CoV-2 was published in January 10, 2020. In this article we describe the steps that we have follow up to develop a vaccine candidate using as a vector (vehicle) an attenuated strain of modified vaccinia virus strain (MVA) expressing the full-length S (Spike) protein of SARS-CoV-2. We have demonstrated in cultured cells and in animals (mice) that the vaccine fulfills relevant criteria to be considered a candidate against COVID-19, like expression of the entire protein at the cell membrane, formation of oligomers (trimers), high stability and ability to induce neutralizing antibodies, a type of Th1 response and induction of a wide spectrum of SARS-CoV-2 specific T cells, like CD4+, CD8+, Tfh, Tregs and memory cells. We have programmed efficacy studies in animals (humanized mice and macaques) and phase I/II and III clinical trials. The GMP lot is under production by an Spanish company and a patent has been presented.