Extent of cross-resistance between agents used to treat human immunodeficiency virus type 1 infection in clinically derived isolates

The phenomenon of cross-resistance to, antiretroviral agents used to treat human immunodeficiency virus type 1 infection is well known but so far has been only qualitatively described. Here, we quantitate the degree of cross-resistance among all commonly, prescribed antiretroviral agents in almost 5,000 clinically derived recombinant isolates collected in the United States since January 2000.