Question

You want to make a live virus vaccine against the COVID-19 virus by using zoonotic coronaviruses, i.e. coronaviruses that currently infect other species and therefore grow poorly in humans.

i) What is the advantage of using a virus for the vaccine instead of just injecting spike protein from the COVID-19 virus

ii) You obtain the DNA sequence of two coronaviruses that infect bats or foxes. The partial sequence of the spike protein from the human virus, and from these two species is given below. The uppercase ATG indicates the start codon. Which virus would you select for the vaccine? Why?

iii) How might you modify the virus you selected to increase its potency as a vaccine? Why potential problems might this cause

COVID-19​​ca ATG ttt gtt ttt ctt gtt tta ttg cca …

Bats ​​ga ATG ttc cta ttc cta gta ctg ctt ccg …

Foxes​​ct ATG tct gct tct cat gat gta tcg cca …

Answer 1

And -1 .) Valence of epitopes as well antigenic diversity will be much more in case of complete virus then just a spike protein. Valence determines the number of antibody molecules that can combine with the antigen at one time. so a complete virus particle will elicit a more effective immune response as compare to just a spike protein.

Ans-2.) corona virus infecting foxes will be a good candidate among all as the amino acid sequence encoded by this DNA sequence is much more heterogeneous as compare to that one coded by bat and human. Since more Hetrogenous the antigen is, higher will be it's immunogenity .

Ans-3.) Potency can be increased by administrating it with an adjutant.

An adjutant is a substance that when mixed with immunogen and injected with it, enhances the immune response against immunogen.

Monitoring the dosage and route of administration.

Antigens administered subcutaneously ,generally elicit the strongest immune system.