Question

The novel coronavirus, SARS-Cov2, which is responsible for the disease Covid-19 is a positive strand RNA ((+)ssRNA) virus. From what you learned in BIOL1020, suggest a model of how the SARS-Cov2 genome is replicated. The key enzyme for viral replication is unique to the virus and not found in the human host. What is the name of the enzyme, what is its enzymatic function, and how would you explain that a drug called Remdesivir (an adenosine analogue that causes premature termination of RNA synthesis) is currently the most promising drug against a range of RNA viruses, including Ebola ((-)ssRNA virus), MERS ( (+)ssRNA virus ) and SARS-Cov2 ((+)ssRNA virus)?

Answer 1

SAARS-Cov2 is a positive sense single stranded RNA. After entering into host cell , its positive sense RNA encodes a special type of protein called RNA dependent RNA polymerase which is used to synthesis mRNAs that will be used to form many subgenomic mRNAs from which other proteins, necessary for virus assembly and structure formation are formed. This RNA dependent RNA polymerase take the positive sense genomic RNA of the virus as a template for synthesis of various subgenomic mRNAs .

A drug called Remdesivir is an adenosine analogue which when incorporated into the forming mRNAs block further elongation of mRNAs and causes premature termination of mRNAs. As the mRNAs are not synthesized , proteins are also not synthesized and as a result the structural proteins are not being made by the virus. So new virus are not formed and this is the mechanism by which the spread of the virus can be prevented.