Question

Why do you think there are three primer/probe sets for SARS-CoV-2?

Answer 1

Three primers are

Oligo-dT primers

Random primers and

Sequence specific primers.

As the genome of this viral particle is RNA.

mRNA with poly A tail can be primed with oligo dT primers which have an anchor and bind to the poly A tail of mRNA for genration of complete cDNA from mRNA.

Some Random primers are added which give high cDNA yield. They anneal to all the RNA( tRNA, rRNA, mRNA) and can be used in case of significant secondary structures.

Sequence specific primers for mRNA are Targeting to the specific sequence of viral genome with high sensitivity and specific cDNA pool.