Tyrant / Progenitor virus variant (Wesker virus)

In Wesker's Report, it is revealed that Birkin gave Wesker a variant of the T-virus to use when he faked his death in Resident Evil, and as a side-effect he received superhuman strength and speed. It has no visible side-effects besides changing the color of his eyes. According to Capcom's Resident Evil website, the virus is a version of the T-virus.[2]

The virus speeds the host's metabolism, giving it heightened strength, speed, and regenerative abilities. Unlike the other viruses featured in the series, it is not a severely mutagenic virus, and its effects are limited to muscle tissue and lower organs, leaving the nervous system untouched.

As a prerequisite to increasing the host's speed, the virus also affects ocular tissue, allowing it to view and process visual information at a speed allegedly equatable to raptors. This modification of the eyes is the only visible effect of the virus on its host.

The virus is discussed in one of the files of Resident Evil: The Umbrella Chronicles. This file, called "Memo about Virus", explains that the virus is from the "mutation stocks". Requiring an injection of at least 5 minutes prior to use, 10% of subjects fail to revive, while 20% revive as they were originally and 70% revive with its beneficial mutations to the muscle system and circulatory system.

In Resident Evil 5, the virus Wesker injected himself with is revealed to be an altered strain of the Progenitor virus which gave him the superhuman abilities that the Ndipaya tribe's leaders acquired after successfully consuming the Progenitor flower. Its also revealed that the virus Wesker injected himself with is unstable and that he has to inject himself with serum called PG67A/W, also developed from the progenitor virus, that is said to keep the virus in check.