Nef gene: Short for negative factor gene, a gene the absence (or defect) of which diminishes the strength of a disease.
The term Nef gene was coined in 1989 in respect to HIV (the human immunodeficiency virus) and AIDS. The Nef gene in this situation is a gene in HIV the absence (or defect) of which diminishes the strength of AIDS.
The term "Nef gene" is now considered to have entered into the English language, according to the Quarterly of New Words edited by DK Barnhart. Nef gene is also written NEF gene or NeF gene or nef gene and is sometimes shortened to nef.