Low incidence of genotypic and phenotypic resistance in paediatric HIV-infected patients on long-term first-line antiretroviral triple therapy

Virologic and immunologic response to antiretroviral therapy and predictors of HIV type 1 drug resistance in children receiving treatment in Abidjan, Côte d'Ivoire

We describe changes in HIV-1 viral load, CD4+ T cell percentage, and incidence of drug resistance and factors associated with drug resistance for 134 children receiving antiretroviral therapy (ART) for approximately 1 year in Abidjan. Between August 1998 and September 2003, ART was initiated for 395 HIV-infected children ages 0-15 years in the Côte d'Ivoire national drug access initiative. All 1-year samples with detectable HIV RNA >1000 copies/ml were tested for HIV-1 drug resistance and changes in viral load and CD4+ T cell counts were also determined. At treatment initiation, 80% of children had CD4+ T cell percentages <15% and a median viral RNA load of 5.6 log copies/ml. The median age at treatment initiation was 7 years with only 25% of patients less than 4 years of age. Of the 134 children receiving therapy, 72 (54%) had undetectable viral load. The estimated 1-year viral load decline was 1.9 log10 copies/ml and the CD4+ T cell percentage increase was 10.9%. The estimated 1-year cumulative probability for developing any class of drug resistance was 0.44 (95% CI, 0.35, 0.53). In a multivariate analysis, the magnitude of virologic response to therapy was inversely associated with development of drug resistance. Children with less CD4+ T cell rise from baseline values and the use of dual therapy were also associated with the development of drug resistance. Guidelines are needed for the treatment of pediatric HIV infection in Africa in order to minimize the occurrence of drug resistance and enhance better virologic, immunologic, and clinical outcomes.

Genotypic resistance and HIV-1 subtype in Brazilian children on dual and triple combination therapy

BACKGROUND

Antiretroviral therapy is provided by the Brazilian Ministry of Health to eligible HIV-infected individuals. Based on clinical and immunological classification, the Brazilian guidelines recommend dual or triple therapy for children. However, the development of drug-resistant strains or poor adherence to therapy could impact the efficacy of this approach.

OBJECTIVES

We examined relationships between RNA levels, CD4+ T-cell counts, treatment history, and the prevalence of drug-resistant variants in a cohort of HIV-1-infected children in Rio de Janeiro, Brazil.

STUDY DESIGN

Direct sequencing of reverse transcriptase and protease genes from plasma was performed. Virologic and CD4+ T-cell counts responses to therapy were assessed by changes in HIV-1 RNA levels and CD4+ T-cell counts from baseline.

RESULTS

Thirty-seven patients were receiving dual therapy and 38 were on triple therapy at enrollment, segregated by antiretroviral history. Both groups had a higher increase in CD4+ T cell counts and a lower viral load in pre-treatment antiretroviral-naïve subjects. Notably, there was a direct correlation between the higher frequencies of drug-resistance mutations and cross-resistance with previous usage of antiretroviral (ARV) therapy in both groups. Non-B subtypes isolates were found in 21.3% of samples. A smaller increase in CD4+ T cell counts was found between non-B subtypes when compared to B-subtypes.

CONCLUSIONS

These results suggest that less immunological recovery and a higher number of mutations related to drug resistance were associated with previous usage of ARV and consequent higher time under drug selective pressure in these HIV-infected Brazilian children. These facts suggest the preferential use of triple drug combination as first line regimen in children.

Testing genotypic and phenotypic resistance in human immunodeficiency virus type 1 isolates of clade B and other clades from children failing antiretroviral therapy

The emergence of resistance to antiretroviral drugs is a major obstacle to the successful treatment of human immunodeficiency virus type 1 (HIV-1)-infected patients. In this work, we correlate clinical and virological trends such as viral load (VL) and CD4 counts to genotypic and phenotypic antiretroviral (ARV) resistance profiles of HIV-1 isolates from the B and non-B subtypes found in vertically infected children failing ARV therapy. Plasma samples were collected from 52 vertically HIV-1-infected children failing different ARV therapies. Samples underwent HIV-1 pol sequencing and phenotyping and were clustered into subtypes by phylogenetic analysis. Clinical data from each patient were analyzed together with the resistance (genotypic and phenotypic) data obtained. Thirty-five samples were from subtype B, 10 samples were non-B (subtypes A, C, and F), and 7 were mosaic samples. There was no significant difference concerning treatment data between B and non-B clades. Prevalence of known drug resistance mutations revealed slightly significant differences among B and non-B subtypes: L10I, 21 and 64%, K20R, 13 and 43%, M36I, 34 and 100%, L63P, 76 and 36%, A71V/T, 24 and 0%, and V77I, 32 and 0%, respectively, in the protease (0.0001 </= P </= 0.0886), and D67N, 38 and 8%, K70R, 33 and 0%, R211K, 49 and 85%, and K219Q/E, 31 and 0%, respectively, in the reverse transcriptase (0.0256 </= P </= 0.0704). Significant differences were found only in secondary resistance mutations and did not reflect significant phenotypic variation between clade B and non-B.

Antiretroviral drug resistance among HIV-1 infected children failing treatment

High levels of HIV-1 replication occur following perinatal infection and antiretroviral drugs may not fully suppress viral load during the early years of childhood. Adherence to treatment may also be difficult among children. These two factors will contribute to development of drug resistance but limited paediatric data are available. This study has, therefore, evaluated the prevalence of drug resistance among children and assessed the contribution of adherence to failing therapy. Samples from 26 children who had experienced virological failure to antiretroviral therapy were tested for drug resistance using the Visible Genetics TRUGENE trade mark HIV-1 genotyping assay. HIV-1 subtype was determined using a peptide-based EIA and drug adherence determined by physician assessment. Twenty-four children were black African, 23 of whom were infected with a non-B subtype. HIV RNA sequence data was obtained for 21 of the 26 children; at treatment failure resistance mutations were detected in the protease gene of 7 (33%) and the reverse transcriptase gene of 19 (90%). A lower proportion of children had evidence of drug resistance at nadir and no resistance mutations were detected prior to treatment. Genotypic resistance was common in those treated with lamivudine (10/11, 91%), nevirapine (6/8, 75%), and zidovudine (7/11, 64%). The prevalence of mutations was lower among those receiving other nucleoside reverse transcriptase inhibitors and protease inhibitors. In 50% of children, drug adherence was >90%. Antiretroviral drug resistance was common among this group of children failing therapy, the majority of whom were infected with non-B subtypes of HIV-1. As adherence to treatment was low in 50%, this was likely to be an important contributory factor.