Which HIV Tropism Test Is Preferred: Genotypic or Phenotypic?

The use of maraviroc, a CCR5 antagonist, is restricted to patients who have only CCR5-using HIV as determined through a tropism test. In the U.S., HIV tropism testing is routinely performed through a phenotypic assay, because genotypic testing is not commercially available.

In the present study, researchers evaluated the predictive ability of two genotypic assays — one using triplicate population sequencing (TPS) alone and a novel assay incorporating both TPS and deep sequencing technology (the Reflex test, Quest Diagnostics) — relative to that of a phenotypic HIV tropism assay, the Trofile Enhanced Sensitivity test (TF-ES, Monogram Biosciences). The three testing strategies were used to retrospectively categorize the pretreatment tropism st…