Which of the following is NOT a mechanism proposed for the broad spectrum antiviral effect of Ribavarin?Group of answer choicesReduction in GTP levels within the cell.Inhibition of virus release from the endosome.Inhibition of mRNA 5’ capping.Increased frequency of mutation by viral polymerase.None of the above.

The mechanism that is NOT proposed for the broad spectrum antiviral effect of Ribavirin is "Inhibition of virus release from the endosome."

Here's why:

1. Reduction in GTP levels within the cell: Ribavirin is a guanosine analog that can deplete the intracellular GTP pool, thus inhibiting viral replication.

2. Inhibition of mRNA 5’ capping: Ribavirin can inhibit the viral mRNA cap formation, which is crucial for viral protein translation and replication.

3. Increased frequency of mutation by viral polymerase: Ribavirin can cause lethal mutagenesis in RNA viruses by increasing the mutation rate during viral replication.

However, there is no substantial evidence or widely accepted theory that suggests Ribavirin works by inhibiting virus release from the endosome. Therefore, this is not a proposed mechanism for the antiviral effect of Ribavirin.