(DeCandido's novelizations of the Anderson films)
The T-virus was a mutagenic virus engineered by the Umbrella Corporation for a multitude of usages ranging from medicinal application to skin cream to biological weaponry.
The T-virus was the brainchild of Dr. Charles Ashford. Intending it to potentially treat cellular damage in a variety of conditions, he had expectations of it being sold as a regenerative skin cream.
In 2002, T-virus development was shifted out of Ashford's reach and given over to Drs. Mariano Rodriguez and Anna Bolt at The Hive, an underground laboratory beneath Raccoon City. Ashford looked to this with great suspicion; while they were brilliant scientists, they were not experienced in researching for corporations and so were liable to manipulation.