Covert or widespread deployment in civilian areas are effective ways to start a T-virus outbreak; battlezone conditions tend to stymie it's growth
The victim experiences powerful fevers as the infection progresses, and eventually loses brain function and dies. Within a period of one to three hours, the victim will regain minor brain function and rise again as a zombie
The primary bounty of Wraith's pillaging of Umbrella Corporation's assets. Though many of Umbrella's more exotic bio-organic weapons escaped acquisition or were destroyed, the T-virus found its way back to Wraith's labs where it was refined for deployment by Professor Konta. The strain primarily used by the Angels is more a terror weapon and less a military one; to that end, communicability has been considerably reduced, its ability to circumvent the immune system has been improved, and its incubation time has been hurried. The Angels' T-virus strain has a painfully limited ability to survive outside of an infected host and can normally be transmitted only through direct injection into the bloodstream, which most usually occurs through zombie bites or creep wounds. In exceptionally high concentrations, however, the virus can infect people through other body cavities such as the mouth or nose; the Angels' plan to spread the T-virus in part of Tokyo's water supply was only feasible with a purpose-built concentration of virus. The modifications to the original strain also seem to have toned down its mutation capacity in humans, while increasing its capacity in certain other creatures that don't have a complex immune system, though this may have been unintentional. The Angels' strain was modified specifically so that when an outbreak occurred, it wouldn't spread too far and could be militarily contained without much trouble (the exact opposite of Umbrella's intentions), as the Freedom's Angels always intended to use the weapon within their own territory.