I think he's talking about the anti-virus for the T/C/whatever-virus, and the lore around it.
Far as I know, there is no such thing. They never cure the viruses, though there is no reason to, considering they don't exactly have any form of being carried aside from gas or direct contact with some zombies. Besides, the whole point of the viruses is that you transform into a B.O.W. in seconds so that you can destroy the enemy with relative ease. The only antivirus that could help would be one attached to the virus so that it can't function. So already being immune to the virus, like Jake. Which is antibodies, not an antivirus.
4 and 5 didn't even have viruses, they had parasites. 6 also has parasites with the J'avo, though the zombies had the C-Virus.
Nah, RE6 doesn't have any parasites - it's just that the virus mutates people in different ways depending on how they were infected (like how the Yersinia pestis is responsible for three different diseases). "Anti-virus" is a pretty stupid term, though - I can understand it in the Anderson films because it's meant to be like that. It probably means "anti-retroviral drugs".