The Trofile assay is a blood test that identifies the tropism of a patient's HIV.
A molecular assay, Trofile was developed by Monogram Biosciences for use in HIV treatment. The assay's purpose is to identify the tropism of an individual patient's HIV strain – R5, X4, or a combination of these known as dual/mixed (D/M). The results show whether the patient is infected with virus that enters cells using the R5 co-receptor, the X4 co-receptor, or both (dual/mixed).
Patients with strains of HIV that prefer the R5 receptor tend to remain healthy longer than those with the strains that prefer X4. However, over the course of the disease, a patient's viral population may undergo a "tropism switch" from R5 to X4.
Development and characterization of a novel single-cycle recombinant virus assay to determine human immunodeficiency virus type 1 coreceptor tropism. Antimicrob Agents Chemother. 2007;51(2):566-575. (Whitcomb JM, Huang W, Fransen S, et al.)