But the special thing about these retroviruses is and that's actually where they obtain their name they are able to actually synthesize viral DNA molecules from RNA and that is in reverse of what happens in our own cells and all other living cells. So, however, a category of viruses called retroviruses can synthesize DNA from RNA by using a special type of protein that is found in that retrovirus known as reverse transcriptase. And so one example is the HIV agent. So let's take a look at the following diagram to basically see how retrovirus actually works. So inside the protein capsite of the retrovirus, we have two single strands of RNA molecules. So retrovirus has two copies of a single stranded RNA molecule.