The G-virus is a highly-advanced strain of the Progenitor Virus possessing fierce-regenerative abilities capable of essentially granting infectees biological immortality. First featured in Resident Evil 2.
The G-virus was developed by Umbrella Corporation scientist William Birkin, who had also done pioneering work on the t-virus.
A primitive form of the virus was discovered in the mutated body of Lisa Trevor, on whom the Umbrella Corporation had been conducting unethical genetic and viral experiments for three decades. When she displayed unexpected immune resistance to the experimental NE-Alpha parasite, Birkin and other researchers looked for a cause and found what would later become the G-virus.
Characteristics of the G-virus
Vials containing t-virus and G-virus samples.The G-virus, shown as a purple, aqueous liquid in a glass vial in, greatly increases the host's metabolism, accelerating cellular duplication and revitalization of dead cells at the cost of higher brain function by continual destruction of mitochondria in neurons, causing the infected person to degrade to sub-human levels. The host exhibits animalistic behavior, loss of moral reasoning and memory, and becomes driven by self-preservation. Ultimately, carriers become creatures simply dubbed G.
Flaws of the G-virus
A third eye on some part of the body (typically the shoulder) was a common feature of creatures imbued with the G-virus.Beyond these qualities, the mutations induced by the virus tend to be extremely volatile. The only known hosts were William Birkin, his daughter Sherry and Curtis Miller. William injected himself with the virus after being mortally wounded by an Umbrella Security Service unit attempting to recover the G-virus from his labs. Unlike t-virus hosts, G-virus hosts never stop mutating, even without external stimuli, thus causing transformations akin to a sort of artificial evolution, accelerated to levels impossible to be recreated in nature. G-Carriers evolve even faster when wounded, due to the incredible regenerative capabilities of infected cells. Curtis injected himself to denounce the "atrocities" by the WilPharma company, which, in its quest to create a viable T-Virus vaccine, had apparently infected countless people to use as guinea pigs. Sherry was impregnated by William. As their DNA matched, she was destined to become like him. The mutations were stopped before begining, but the G-virus remained in her body, dormant.
William Birkin underwent distinct stages of transformation each time he was weakened, and it is most likely other G-Carriers would also undergo similar stages, although the unpredictable nature of G-virus mutations means that the details would differ. It must also be noted that Birkin was in an extremely decrepit state when he injected the virus into himself; this played an important part in his mutation and influenced the changes his body underwent; thus, it was be assumed all G-Carriers shall evolve in a different way, depending upon their state of health, time of infection, and details such as those. This was demonstrated by the changes seen upon Curtis Miller, whose changes were influenced as well by the injuries he sustained, and developed characteristics vastly different from Birkin, such as an elongated prehensile tail, height beyond ten feet, and an initial phase upon which he was still practically fully conscious; all of this, even though he retained a massive eye and claws as a nod to Birkin's changes.
Despite the massive shapeshifting, the virus apparently leaves traces of the memory intact, allowing brief sparks of sanity in the minds of the afflicted. However, such sparks are brief and usually end in the complete destruction of the host's mind, leaving only mindless, berserk mutants of unimaginable power. Because of this, the G-Virus is seldom considered to be a viable option for bioterrorism.
People mutated with G undergo drastic mutations when injured. William Birkin suffered 5 of these mutations, with each more gruesome than the last. The first being a larger version of himself, albeit pink and with an enlarged arm which was created due to his injuries from the failed assassination attempt. He reacted to injuries and thus mutated again, becoming less and less human until becoming a large blob.
After a person with different blood-type than the G is implanted with a G-embryo through forced ingestion, the host, after several minutes, develops severe chest pains, due to the developing creature consuming the internal organs, similar to certain sea animals in their first stages of life. This creature-bearing a strong resemblance to the 'chest burster' from the Aliens franchise-will burst out of the chest. This almost always has the appearance of a legged lump of flesh vaguely resembling the shape of a tear of about ten to fifteen centimetres in length, which grows to abnormal sizes and develops aberrant body parts, such as oversized eye balls, or enormous limbs. This probably is due to the fact the G-virus within them reacts adversely due to genetic rejection when absorbing the DNA of the unwilling host, because this virus had already absorbed the blood of William Birkin himself; thus, should anyone without a genetic compatibility to Birkin be infected with the virus, they would always spawn G-Creatures. It is unknown what would happen if the opposite reaction were to be undertaken: that a compatible genetic carrier became the host for one of the imagos. Nevertheless, as the last remainder of Birkin's known direct matches is his daughter Sherry, and given she is currently under the custody of Albert Wesker (and given the unique bond between Wesker and Birkin), it is extremely unlikely she herself shall become the host for one of the beings.
William Birkin, Sherry Birkin, Chief Irons and Ben Bertolucci - non-canon Monica Curtis Miller
Means of Infection
Infection by the G-virus is caused by injection or ingestion of the virus, but unlike creatures infected with the t-virus, G-mutants cannot pass infection on to other creatures through physical contact or injury. Instead, they create offspring by orally implanting small, parasitic organisms into a live host through the palm of the hand, in the case of William Birkin. In unfortunate cases, a host who has no compatible DNA match will reject the parasite in a matter of hours or less. The embryo rapidly grows inside its host before bursting from their chest (a homage to the Alien movie series). Upon exiting the host body, the embryo quickly mutates into its adult form.
Within Resident Evil 2, the G-virus rejected embryo is encountered in the sewers, following its rejection from a genetically dissimilar host, commonly called a G-Imago; it was a large, slow creature devoid of flesh that possessed with an elongated neck and seemingly stood hunched over; this was due to the fact that the right side of its body was vastly disproportionate in comparison to its left region, as a result of unequal bilateral symmetry, which conversely was a result of its cellular instability by the uncontrolled merging of the virus with two different DNAs. The creature also periodically vomited G-Embryos which would cling to the opponent in an attempt to disorient him as the G-Imago attacked.
The G-Imago found in Resident Evil Outbreak above the subterranean Umbrella laboratories, after bursting forth from Monica's body, likewise, possessed similar features such as an elongated neck, exposed muscle tissue, and the ability to spawn G-Embryos; its body also lacked bilateral symmetry as evident by the fact that its left arm is smaller than its right. As opposed to the G-Imago in the sewers, this offspring is quite tall and possesses a large sac on its dorsal cavity covered with bullas in addition to a tail.
A DNA match can only be achieved by a person geneticaly similar to the G-mutant and being impregnated by it. The embryo begins to pupate and assimilate the host body, turning them into what can only be assumed to be a mutant of immense strength. Sherry Birkin was infected by her father, but the infection was stopped with an experimental anti-G vaccine, codenamed DEVIL, before mutation could occur with help from her mother Annette Birkin and Claire Redfield. It must be noted, however, that DEVIL did not destroy the cells infected with the G-virus, it merely halted its spread through Sherry's body; thus, Sherry still has viable samples of the virus within her system.
Differences from the T-virus
The G-Virus composition.The G-virus is quite different to the t-virus in terms of action and transmission. While both viruses have the characteristic of inciting mutation in infected organisms, the similarities end there. The G-virus has none of the necrotic properties of the t-virus, and as such, host organisms do not decompose (the characteristic rotting of the zombies).
The G-virus is also far less virulent than the t-virus, for while the t-virus can be transmitted by body fluids, direct attack from an infected organism, or even water, the G-virus can only be transmitted by direct injection or active impregnation of a parasite into the prospective host by a G-mutant (as evident by Birkin). G-mutants instinctively attempt to reproduce as any other animal species; in this manner, G-virus hosts act much more like living creatures than those infected with the t-virus; while t-virus infection can be considered accidental (as the host does not actually mean to infect its victim), G-mutants actively attempt to perpetuate their species. This has the frightening implication that, while the t-virus is infinitely more contagious, a G-virus epidemic would be uncontrollable and actively hostile to humanity, as G-mutants would seek to reproduce over any other instinct.
The G-virus also acts exponentially faster than the t-virus, with William Birkin manifesting considerable physical mutation mere seconds after infection. Apparently, direct injection of the virus is incurable, as it acts too quickly for a vaccine to be effective. Infection by parasitic impregnation, however, can be controlled much like the t-virus, with a vaccine being effective if administered during the initial stages of infection, before the embryo can gestate. While the t-virus' effects on long term, controlled exposure are well documented (Tyrant, the Hunters and the Lickers for instance), the effects of such exposure to the G-virus are unknown, as there was no testing in this field done before the Raccoon City incident. However, results of such manipulation of the virus COULD be seen in future sequels of the series, considering both HUNK and Ada Wong were able to procure samples of the virus for Umbrella and Albert Wesker, respectively.
However, if the effect of said exposure was similar to the t and t-Veronica virus', such organisms would theoretically be the absolute deadliest creatures ever made by Umbrella. Birkin himself, a G-mutant, was more powerful and deadly than any creature created with the t-virus on purpose. The effects of the G-virus on non-human hosts is unknown, but they are probably just as radically powerful and unstable as their human counterparts in comparison to the t-virus. Additionally, the DEVIL sample was delivered within a short time. In either case, it is unlikely the G-virus, given its horribly virulent effects, would not have been at the very least fused with some part of Sherry, hinting at the probability she is still a viable carrier.
Shortly before leaving with the S.T.A.R.S Alpha Team, Birkin gave Wesker a syringe containing a virus. After using it to fake his death at the hands of the T-002 Tyrant, he escaped the underground facility, becoming a Metahuman.
There are many similarities between Wesker's infection, Lisa's primitive G-strain, and the finished virus. It seems that Wesker used a primitive strain of the G-virus. Both Wesker's and Lisa's strains do not cause severe random mutations as is seen with Birkin's strain, and neither do they cause any drop in intelligence. Although thought to have caused her madness by fans, Lisa's development of mental illness was due trauma and other viral injections.