Question

A vaccine for Coronavirus is likely to take a longer time than imagined, because the most obvious target of the vaccine should be the external spike protein on the envelope of this enveloped virus. The cellular attachment protein on epithelial cells, which the virus binds to for entry into the epithelial cell, is known to be ACE2, a receptor enzyme. Explain why the production of a vaccine targeting the coronavirus spike protein (S1), is not likely to be successful.

Answer 1

SARS-CoV-2 is a positive-strand RNA virus that belongs to the group of Betacoronaviruses. It has a long ORF1ab polyprotein at the 5’ end and the 3’end of the genome encodes 4 major structural proteins, including the spike (S) protein, nucleocapsid (N) protein, membrane (M) protein, and the envelope (E) protein. SARS-CoV-2 binds to the receptor angiotensin converting enzyme 2 (ACE2) on epithelial cell for the virus entry and for subsequent pathogenesis which results in severe respiratory illness with symptoms of fever, cough, severe headaches and shortness of breath.

Vaccines are the most necessary and effective tool against the lethal/ infectious Corona virus and different pharmaceuticals companies across the world have developed vaccines by different methods.

Spike Protein (S Protein)

S protein is currently the most promising antigen formulation for SARS-CoV-2 vaccine research. First, it is external exposure and thus is able to be directly recognized by host immune system also it mediates the interaction with host cell by binding to the receptor ACE2 which is essential for subsequent virus entry to target ( epithelial) cells and causing subsequent pathogenicity. The homologue proteins were already used for vaccine development against the virus might prove to be effective. The S protein consists of two sub units and twwo subunits ( S1 and S2) are further devided into 3 domains. Various research are ongoing with this domains role and how to design vaccine based on this protein. Presently, no success is found while working on the role of respective domains of S1 protein and more work to be done.