Effect of Genotypic Resistance on the Virological Response to Highly Active Antiretroviral Therapy in Cerebrospinal Fluid

Paired plasma and cerebrospinal fluid (CSF) specimens drawn from 15 HIV-infected patients with neurological disease before and after a median 6-week duration of highly active antiretroviral therapy (HAART) were studied to assess the short-term virological response of CSF and whether this can be predicted on the basis of baseline resistance mutations. After treatment, the median plasma and CSF viral load (VL) decreased by, respectively, 2.08 log₁₀ (p = 0.0001) and 0.91 log₁₀ copies/ml (p = 0.007) in comparison with baseline. A plasma virological response was observed in all but one patient, whereas the posttreatment CSF VL increased, remained unchanged, or decreased at a substantial lower rate than in plasma of six "CSF non/slow responders" (40%). Direct sequencing of baseline specimens showed that none of these patients had reverse transcriptase (RT) or primary protease resistance mutations in the CSF alone, but two had RT mutations conferring high-level resistance to drugs included in the HAART regimen in both CSF and plasma. The other four patients had no RT or primary protease resistance mutations. There was no significant difference in the nucleotide diversity of the CSF and plasma RT sequences, baseline plasma or CSF VL, the CSF-to-plasma VL ratio, the number of CSF cells, the CD4⁺ cell counts, or the history of antiretroviral treatment between the CSF non-slow responders and the other patients. During this short-term follow-up and despite a plasma response, a significant proportion of HAART-treated patients with neurological symptoms showed a slow or absent CSF response. Most of these cases were not associated with the presence of resistant HIV strains in the CSF.