(Capcom's primary storyline)
V-ACT is the name attributed to Umbrella for the re-activation of the t-Virus following a period of dormancy. t-Virus variants using the V-ACT process will activate when the human host is incapacitated (by either falling into a coma from starvation, or being severely wounded), prompting significant mutations as a last ditch effort to ensure the host's body's "survival".
The origins within V-ACT lie with the Tyrant Project, which sought in part to redevelop the t-Virus to cause more mutations in humans. The first case of V-ACT induced by accident took place in May 1998, when one of the Umbrella USA researchers overseeing surgery on the T-002 was exposed to the ε strain, which could existe as an airborne pathogen in certain circumstances. The scientists began studying the man closely, ultimately giving the mutant form the name "Crimson Head", and he himself "Prototype 1". Initially kept for further study, with a sample of Epsilon extracted, he became a security risk after killing several people during feeding and was quickly forced into a coffin behind the Spencer Mansion.[excerpt 1] As the virus' spread across the facility slowly became apparent, other employees began falling ill, becoming Zombies and, finally, into Crimson Heads. With the employees not trained for handling such creatures, they had little means to protect themselves other than to destroy the bodies of unconscious Zombies.
By September 1998, a mutant strain of Epsilon had been engineered by Umbrella and was available in laboratories across the world from NEST near Raccoon City, and on Sheena Island. This strain instead caused Zombies to mutate into skinless, four legged mutants dubbed "Lickers" due to their long tongues.
This term has also been used to classify the C-Virus mutation known as Bloodshot. Due to the C-Virus containing genetic materials from the T-Veronica Virus, itself being a variant of the t-Virus, it too shares the ability to use a form of V-ACT in C-Virus Zombies. When a Zombie's body becomes heavily damaged, namely head trauma, it can potentially further mutate into a Bloodshot.
- Excerpt from biohazard Kaitai Shinsho, p.078:
"「V-ACT」という機能と、 それをもたらすウィルスの存在を研究者たちに気づかせるきっかけを作った。最初のクリムゾン・ヘッド。 プロト１を生み出したタイプのt−ウィルスは、 のちに培養生産されたが、 その影響で誕生した―般のクリムゾン・ヘッドよりはるかに高い生命カ・戦闘能力を持つ。周囲の者すべてを瞬時に惨殺するほど狂暴なため解析は不可能とされたものの、 貴重なサンプルであることにちがいなく、 いつの日が調査研究を行なうために封印されている。"
- Hamamua (ed.), Kaitai Shinsho, p.078.