Genotypic predictions performed well in paired genotypic and phenotypic assessment of HIV-1 coreceptor usage. Multicenter studies analyzing the correlations between the genotypic determination of HIV-1 tropism and clinical response to CCR5 antagonists are needed to validate this approach in clinical practice.

Plasma or PBMC samples can be used for determining HIV-1 tropism during primary infection. CXCR4-using viruses are rare during primary infection but increase the risk of disease progression.