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Introduction: ACTG A5288 was a strategy trial conducted in diverse populations from multiple continents of people living with HIV (PLWH) failing second-line protease inhibitor (PI)-based antiretroviral therapy (ART) from 10 low- and middle-income countries (LMICs). Participants resistant to lopinavir (LPV) and/or multiple nucleotide reverse transcriptase inhibitors started on third-line regimens that included raltegravir (RAL), darunavir/ritonavir (DRV/r) and/or etravirine (ETR) according to their resistance profiles. At 48 weeks, 87% of these participants achieved HIV-1 RNA ≤200 copies/ml. We report here long-term outcomes over 144 weeks., Methods: Study participants were enrolled from 2013 to 2015, prior to the availability of dolutegravir in LMICs. "Extended Follow-up" of the study started after the last participant enrolled had reached 48 weeks and included participants still on antiretroviral (ARV) regimens containing RAL, DRV/r and/or ETR at that time. RAL, DRV/r and ETR were provided for an additional 96 weeks (giving total follow-up of ≥144 weeks), with HIV-1 RNA measured at 48 and 96 weeks and CD4 count at 96 weeks after entry into Extended Follow-up. Proportion of participants with HIV-1 RNA ≤200 copies/ml was estimated every 24 weeks, using imputation if necessary to handle the different measurement schedule in Extended Follow-up; mean CD4 count changes were estimated using loess regression., Results and Discussion: Of 257 participants (38% females), at study entry, median CD4 count was 179 cells/mm 3 , and HIV-1 RNA was 4.6 log 10 copies/ml. Median follow-up was 168 weeks (IQR: 156-204); 15 (6%) participants were lost to follow-up and 9 (4%) died. 27/246 (11%), 26/246 (11%) and 13/92 (14%) of participants who started RAL, DRV/r and ETR, respectively, discontinued these drugs; only three due to adverse events. 87%, 86%, 83% and 80% of the participants had HIV-1 RNA ≤200 copies/ml at weeks 48, 96, 144 and 168 (95% CI at week 168: 74-85%), respectively. Mean increase from study entry in CD4 count at week 168 was 265 cells/mm 3 (95% CI 247-283)., Conclusions: Third-line regimens comprising of RAL, DRV/r and/or ETR were very well tolerated and had high rates of durable virologic suppression among PLWH in LMICs who were failing on second-line PI-based ART prior to the availability of dolutegravir., (© 2022 The Authors. Journal of the International AIDS Society published by John Wiley & Sons Ltd on behalf of the International AIDS Society.)

Background: Human immunodeficiency virus (HIV) drug resistance profiles are needed to optimize individual patient management and to develop treatment guidelines. Resistance profiles are not well defined among individuals on failing second-line antiretroviral therapy (ART) in low- and middle-income countries (LMIC)., Methods: Resistance genotypes were performed during screening for enrollment into a trial of third-line ART (AIDS Clinical Trials Group protocol 5288). Prior exposure to both nucleoside reverse transcriptase inhibitors (NRTIs) and non-NRTIs and confirmed virologic failure on a protease inhibitor-containing regimen were required. Associations of drug resistance with sex, age, treatment history, plasma HIV RNA, nadir CD4+T-cell count, HIV subtype, and country were investigated., Results: Plasma HIV genotypes were analyzed for 653 screened candidates; most had resistance (508 of 653; 78%) to 1 or more drugs. Genotypes from 133 (20%) showed resistance to at least 1 drug in a drug class, from 206 (32%) showed resistance to at least 1 drug in 2 drug classes, and from 169 (26%) showed resistance to at least 1 drug in all 3 commonly available drug classes. Susceptibility to at least 1 second-line regimen was preserved in 59%, as were susceptibility to etravirine (78%) and darunavir/ritonavir (97%). Susceptibility to a second-line regimen was significantly higher among women, younger individuals, those with higher nadir CD4+ T-cell counts, and those who had received lopinavir/ritonavir, but was lower among prior nevirapine recipients., Conclusions: Highly divergent HIV drug resistance profiles were observed among candidates screened for third-line ART in LMIC, ranging from no resistance to resistance to 3 drug classes. These findings underscore the need for access to resistance testing and newer antiretrovirals for the optimal management of third-line ART in LMIC., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Antiretroviral therapy (ART) management is challenging for individuals in resource-limited settings presenting for third-line treatment because of complex resistance patterns, partly due to reduced access to viral load monitoring. We aimed to evaluate use of newer antiretroviral drugs and contemporary management approaches, including population-based sequencing, to select appropriate antiretrovirals, plasma viral load monitoring, and interventions to improve adherence in individuals presenting with second-line viral failure., Methods: A5288 was a phase 4, third-line ART strategy study done at 19 urban sites in ten countries that enrolled adult participants with confirmed plasma HIV-1 RNA (viral load) of 1000 copies per mL or more after more than 24 weeks of protease inhibitor-based second-line ART. The primary objective was to use antiretrovirals (raltegravir, etravirine, and ritonavir-boosted darunavir) and diagnostic monitoring technologies, including viral load, genotyping, and adherence support to achieve viral load suppression (defined as ≤200 copies per mL) in 65% or more of participants. ART history and real-time drug resistance genotypes were used to assign participants to one of four cohorts: cohort A (no lopinavir resistance) stayed on second-line ART and cohorts B (B1, best available nucleoside reverse transcriptase inhibitors [NRTIs] plus ritonavir-boosted darunavir plus raltegravir; B2, ritonavir-boosted darunavir plus raltegravir plus etravirine; B3, ritonavir-boosted darunavir, raltegravir, and either tenofovir plus emtricitabine or tenofovir plus lamivudine), C (ritonavir-boosted darunavir plus raltegravir plus tenofovir-emtricitabine or tenofovir plus lamivudine), and D (best available NRTIs plus ritonavir-boosted darunavir plus raltegravir) were defined by increasing levels of resistance and received appropriate regimens, including new antiretrovirals. Participants in Cohort B without detectable hepatitis B surface antigen were assigned by blocked randomisation to cohorts B1 and B2, and those with detectable hepatitis B surface antigen were assigned to cohort B3. The trial is registered with ClinicalTrials.gov, number NCT01641367., Findings: From Jan 10, 2013, to Sept 10, 2015, 545 participants were enrolled. 287 (53%) were assigned to cohort A, 74 (14%) to B1, 72 (13%) to B2, eight (1%) to B3, 70 (13%) to C, and 34 (6%) to D. Overall, 349 (64%, 95% CI 60-68) participants achieved viral suppression at week 48, with proportions varying from 125 (44%) of 287 in cohort A to 65 (88%) of 74 in cohort B1, 63 (88%) of 72 in B2, eight (100%) of eight in B3, 63 (90%) of 70 in C, and 25 (74%) of 34 in D. Participants in cohort A remained on their second-line protease inhibitor, and had the most participants with grade 3 or higher adverse events (147 [51%])., Interpretation: Targeted real-time genotyping to select third-line ART can appropriately allocate more costly antiretrovirals to those with greater levels of HIV drug resistance., Funding: National Institutes of Health., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Limited viral load (VL) testing in human immunodeficiency virus (HIV) treatment programs in low-income countries often delays detection of treatment failure. The impact of remaining on failing protease inhibitor (PI)-containing regimens is unclear., Methods: We retrospectively tested VL in 2164 stored plasma samples from 386 patients randomized to receive lopinavir monotherapy (after initial raltegravir induction) in the Europe-Africa Research Network for Evaluation of Second-line Therapy (EARNEST) trial. Protease genotypic resistance testing was performed when VL >1000 copies/mL. We assessed evolution of PI resistance mutations from virological failure (confirmed VL >1000 copies/mL) until PI monotherapy discontinuation and examined associations using mixed-effects models., Results: Median post-failure follow-up (in 118 patients) was 68 (interquartile range, 48-88) weeks. At failure, 20% had intermediate/high-level resistance to lopinavir. At 40-48 weeks post-failure, 68% and 51% had intermediate/high-level resistance to lopinavir and atazanavir; 17% had intermediate-level resistance (none high) to darunavir. Common PI mutations were M46I, I54V, and V82A. On average, 1.7 (95% confidence interval 1.5-2.0) PI mutations developed per year; increasing after the first mutation; decreasing with subsequent mutations (P < .0001). VL changes were modest, mainly driven by nonadherence (P = .006) and PI mutation development (P = .0002); I47A was associated with a larger increase in VL than other mutations (P = .05)., Conclusions: Most patients develop intermediate/high-level lopinavir resistance within 1 year of ongoing viral replication on monotherapy but retain susceptibility to darunavir. Viral load increased slowly after failure, driven by non-adherence and PI mutation development., Clinical Trials Registration: NCT00988039., (© The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

To screen for drug resistance and possible treatment with Dolutegravir (DTG) in treatment-naive patients and those experiencing virologic failure during first-, second-, and third-line combined antiretroviral therapy (cART) in Uganda. Samples from 417 patients in Uganda were analyzed for predicted drug resistance upon failing a first- (N = 158), second- (N = 121), or third-line [all 51 involving Raltegravir (RAL)] treatment regimen. HIV-1 pol gene was amplified and sequenced from plasma samples. Drug susceptibility was interpreted using the Stanford HIV database algorithm and SCUEAL was used for HIV-1 subtyping. Frequency of resistance to nucleoside reverse transcriptase inhibitors (NRTIs) (95%) and non-NRTI (NNRTI, 96%) was high in first-line treatment failures. Despite lack of NNRTI-based treatment for years, NNRTI resistance remained stable in 55% of patients failing second-line or third-line treatment, and was also at 10% in treatment-naive Ugandans. DTG resistance (n = 366) was not observed in treatment-naive individuals or individuals failing first- and second-line cART, and only found in two patients failing third-line cART, while 47% of the latter had RAL- and Elvitegravir-resistant HIV-1. Secondary mutations associated with DTG resistance were found in 2%-10% of patients failing third-line cART. Of 14 drugs currently available for cART in Uganda, resistance was readily observed to all antiretroviral drugs (except for DTG) in Ugandan patients failing first-, second-, or even third-line treatment regimens. The high NNRTI resistance in first-line treatment in Uganda even among treatment-naive patients calls for the use of DTG to reach the UNAIDS 90:90:90 goals.

In the majority of cases, human immunodeficiency virus type 1 (HIV-1) infection is transmitted through sexual intercourse. A single founder virus in the blood of the newly infected donor emerges from a genetic bottleneck, while in rarer instances multiple viruses are responsible for systemic infection. We sought to characterize the sequence diversity at early infection, between two distinct anatomical sites; the female reproductive tract vs. systemic compartment. We recruited 72 women from Uganda and Zimbabwe within seven months of HIV-1 infection. Using next generation deep sequencing, we analyzed the total genetic diversity within the C2-V3-C3 envelope region of HIV-1 isolated from the female genital tract at early infection and compared this to the diversity of HIV-1 in plasma. We then compared intra-patient viral diversity in matched cervical and blood samples with three or seven months post infection. Genetic analysis of the C2-V3-C3 region of HIV-1 env revealed that early HIV-1 isolates within blood displayed a more homogeneous genotype (mean 1.67 clones, range 1-5 clones) than clones in the female genital tract (mean 5.7 clones, range 3-10 clones) (p<0.0001). The higher env diversity observed within the genital tract compared to plasma was independent of HIV-1 subtype (A, C and D). Our analysis of early mucosal infections in women revealed high HIV-1 diversity in the vaginal tract but few transmitted clones in the blood. These novel in vivo finding suggest a possible mucosal sieve effect, leading to the establishment of a homogenous systemic infection.

Background: Thymidine analogs, namely AZT (Zidovudine or Retrovir™) and d4T (Stavudine or Zerit™) are antiretroviral drugs still employed in over 75% of first line combination antiretroviral therapy (cART) in Kampala, Uganda despite aversion to prescribing these drugs for cART in high income countries due in part to adverse events. For this study, we explored how the continued use of these thymidine analogs in cART could impact emergence of drug resistance and impact on future treatment success in Uganda, a low-income country., Methods: We examined the drug resistance genotypes by Sanger sequencing of 262 HIV-infected patients failing a first line combined antiretroviral treatment containing either AZT or d4T, which represents approximately 5% of the patients at the Joint Clinical Research Center receiving a AZT or d4T containing treatment. Next generation sequencing (DEEPGEN™HIV) and multiplex oligonucleotide ligation assays (AfriPOLA) were then performed on a subset of patient samples to detect low frequency drug resistant mutations. CD4 cell counts, viral RNA loads, and treatment changes were analyzed in a cohort of treatment success and failures., Results: Over 80% of patients failing first line AZT/d4T-containing cART had predicted drug resistance to 3TC (Lamivudine) and non-nucleoside RT inhibitors (NNRTIs) in the treatment regimen but only 45% had resistance AZT/d4T associated resistance mutations (TAMs). TAMs were however detected at low frequency within the patients HIV quasispecies (1-20%) in 21 of 34 individuals who were failing first-line AZT-containing cART and lacked TAMs by Sanger. Due to lack of TAMs by Sanger, AZT was typically maintained in second-line therapies and these patients had a low frequency of subsequent virologic success., Conclusions: Our findings suggest that continued use of AZT and d4T in first-line treatment in low-to-middle income countries may lead to misdiagnosis of HIV-1 drug resistance and possibly enhance a succession of second- and third-line treatment failures.

Objective: To determine drug resistance mutation (DRM) patterns in a large cohort of patients failing nonnucleoside reverse transcriptase inhibitor (NNRTI)-based first-line antiretroviral therapy regimens in programs without routine viral load (VL) monitoring and to examine intersubtype differences in DRMs., Design: Sequences from 787 adults/adolescents who failed an NNRTI-based first-line regimen in 13 clinics in Uganda, Kenya, Zimbabwe, and Malawi were analyzed. Multivariable logistic regression was used to determine the association between specific DRMs and Stanford intermediate-/high-level resistance and factors including REGA subtype, first-line antiretroviral therapy drugs, CD4, and VL at failure., Results: The median first-line treatment duration was 4 years (interquartile range 30-43 months); 42% of participants had VL ≥100,000 copies/mL and 63% participants had CD4 <100 cells/mm. Viral subtype distribution was A1 (40%; Uganda and Kenya), C (31%; Zimbabwe and Malawi), and D (25%; Uganda and Kenya), and recombinant/unclassified (5%). In general, DRMs were more common in subtype-C than in subtype-A and/or subtype-D (nucleoside reverse transcriptase inhibitor mutations K65R and Q151M; NNRTI mutations E138A, V106M, Y181C, K101E, and H221Y). The presence of tenofovir resistance was similar between subtypes [P (adjusted) = 0.32], but resistance to zidovudine, abacavir, etravirine, or rilpivirine was more common in subtype-C than in subtype-D/subtype-A [P (adjusted) < 0.02]., Conclusions: Non-B subtypes differ in DRMs at first-line failure, which impacts on residual nucleoside reverse transcriptase inhibitor and NNRTI susceptibility. In particular, higher rates of etravirine and rilpivirine resistance in subtype-C may limit their potential utility in salvage regimens.

Introduction: Long-term natural history cohorts of HIV-1 in the absence of treatment provide the best measure of virulence by different viral subtypes., Methods: Newly HIV infected Ugandan and Zimbabwean women (N=303) were recruited and monitored for clinical, social, behavioral, immunological and viral parameters for 3 to 9.5years., Results: Ugandan and Zimbabwean women infected with HIV-1 subtype C had 2.5-fold slower rates of CD4 T-cell declines and higher frequencies of long-term non-progression than those infected with subtype A or D (GEE model, P<0.001), a difference not associated with any other clinical parameters. Relative replicative fitness and entry efficiency of HIV-1 variants directly correlated with virulence in the patients, subtype D>A>C (P<0.001, ANOVA)., Discussion: HIV-1 subtype C was less virulent than either A or D in humans; the latter being the most virulent. Longer periods of asymptomatic HIV-1 subtype C could explain the continued expansion and dominance of subtype C in the global epidemic., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives: To determine the impact of HIV-1 subtype on treatment outcomes and the emergence of drug resistance in the resource limited setting of Kampala, Uganda., Design: The Joint Clinical Research Centre (JCRC) in Kampala, Uganda has provided over 2000 drug-resistant genotypes (DRGs) over the past 10 years as standard of care for patients failing therapy and 1403 from treatment-naive and experienced patients over the past 10 years have been analyzed for this study., Method: Viral loads, CD4 cell count, treatment histories and other relevant clinical data was compared with the infecting HIV-1 subtype and DRGs of Ugandan patients failing treatment., Results: Patients failing HAART with DRGs (n = 937) were more frequently infected with subtype D than expected on the basis of the subtype distribution in the treatment-naive population (n = 655) in Kampala (P < 0.001). Higher proportions of treatment failures among subtype D-infected patients were driven by resistance to nucleoside reverse transcriptase inhibitors (NRTI) (P < 0.0002) more than to non-NRTIs (P > 0.04) or protease inhibitors., Conclusion: Higher rates of treatment failure among subtype D as compared with subtype A-infected Ugandans was analogous to the faster disease progression in subtype D-infected patients. The mechanism(s) by which drug resistance may emerge faster in subtype D HIV-1 may relate to higher replicative fitness and increased propensity for a CXCR4 tropism.

We sought to determine the pattern of resistance-associated mutations (RAMs) among HIV-1-infected children failing first-line antiretroviral therapy (ART) and ascertain their response to second-line regimens in 48 weeks of follow-up. The design involved a cohort study within an HIV care program. We studied records of 142 children on ART with virological failure to first-line ART and switched to second-line ART with prior genotypic resistance testing. The pattern of RAMs was determined in frequency runs and the factors associated with accumulation of≥3 thymidine analogue mutations (TAMs) and K103N were determined using multivariate logistic models. Changes in weight, height, CD4, and viral load at weeks 24 and 48 after switch to second-line therapy were determined using descriptive statistics. The children were mean age 10.9±4.6 years and 55.6% were male. The commonest nucleoside reverse transcriptase inhibitor (NRTI) RAM was M184V in 129/142 (90.8%) children. TAMs,≥3 TAMs, 69 insertion complex, K65R/N, and Q151M were observed in 43.0%, 10.6%, 18.3%, 2.8%, and 2.1% of the children, respectively. The commonest nonnucleoside reverse transcriptase inhibitor (NNRTI) RAM was K103N in 72/142 (50.7%) children. The starting ART regimen was associated with accumulation of both≥3 TAMs (p=0.046) and K103N (p<0.0001), while a history of poor adherence was associated with K103N accumulation (p=0.0388). After 24 weeks and 48 weeks of follow-up on lopinavir-ritonavir based second-line ART, 86/108 (79.6%) and 84.5% (87/103) of the children had viral loads<400 copies/ml, respectively. The mean CD4 absolute count increased by 173 cells/μl and 267cells/μl at weeks 24 and 48, respectively. Increments were also observed in mean weight (1.6 kg and 4.3 kg) and height (1.8 cm and 5.8 cm) at weeks 24 and 48, respectively. Multiple RAMs were observed among HIV-1-infected children with virological failure on first-line ART with M184V and K103N most frequent. The children responded favorably to boosted PI-based second-line ART.

Background: Antiretroviral therapy (ART) is indicated during tuberculosis treatment in patients infected with human immunodeficiency virus type 1 (HIV-1), but the timing for the initiation of ART when tuberculosis is diagnosed in patients with various levels of immune compromise is not known., Methods: We conducted an open-label, randomized study comparing earlier ART (within 2 weeks after the initiation of treatment for tuberculosis) with later ART (between 8 and 12 weeks after the initiation of treatment for tuberculosis) in HIV-1 infected patients with CD4+ T-cell counts of less than 250 per cubic millimeter and suspected tuberculosis. The primary end point was the proportion of patients who survived and did not have a new (previously undiagnosed) acquired immunodeficiency syndrome (AIDS)-defining illness at 48 weeks., Results: A total of 809 patients with a median baseline CD4+ T-cell count of 77 per cubic millimeter and an HIV-1 RNA level of 5.43 log(10) copies per milliliter were enrolled. In the earlier-ART group, 12.9% of patients had a new AIDS-defining illness or died by 48 weeks, as compared with 16.1% in the later-ART group (95% confidence interval [CI], -1.8 to 8.1; P=0.45). Among patients with screening CD4+ T-cell counts of less than 50 per cubic millimeter, 15.5% of patients in the earlier-ART group versus 26.6% in the later-ART group had a new AIDS-defining illness or died (95% CI, 1.5 to 20.5; P=0.02). Tuberculosis-associated immune reconstitution inflammatory syndrome was more common with earlier ART than with later ART (11% vs. 5%, P=0.002). The rate of viral suppression at 48 weeks was 74% and did not differ between the groups (P=0.38)., Conclusions: Overall, earlier ART did not reduce the rate of new AIDS-defining illness and death, as compared with later ART. In persons with CD4+ T-cell counts of less than 50 per cubic millimeter, earlier ART was associated with a lower rate of new AIDS-defining illnesses and death. (Funded by the National Institutes of Health and others; ACTG A5221 ClinicalTrials.gov number, NCT00108862.).

Background: Triple nucleoside reverse transcriptase inhibitor regimens have advantages as first-line antiretroviral therapy (ART), avoiding hepatotoxicity and interactions with anti-tuberculosis therapy, and sparing two drug classes for second-line ART. Concerns exist about virological potency; efficacy has not been assessed in Africa., Methods: A safety trial comparing nevirapine with abacavir was conducted in two Ugandan Development of Antiretroviral Therapy in Africa (DART) centres: 600 symptomatic antiretroviral-naïve HIV-infected adults with CD4 counts <200 cells/microL were randomized to zidovudine/lamivudine plus abacavir or nevirapine (placebo-controlled to 24-week primary toxicity endpoint, and then open-label). Documented World Health Organization (WHO) stage 4 events were independently reviewed and plasma HIV-1 RNA assayed retrospectively. Exploratory efficacy analyses are intention-to-treat., Results: The median pre-ART CD4 count was 99 cells/microL, and the median pre-ART viral load was 284 600 HIV-1 RNA copies/mL. A total of 563 participants (94%) completed 48 weeks of follow-up, 25 (4%) died and 12 (2%) were lost to follow-up. The randomized drug was substituted in 21 participants (7%) receiving abacavir vs. 34 (11%) receiving nevirapine (P=0.09). At 48 weeks, 62% of participants receiving abacavir vs. 77% of those receiving nevirapine had viral loads <50 copies/mL (P<0.001), and mean CD4 count increases from baseline were +147 vs. +173 cells/microL, respectively (P=0.006). Nine participants (3%) receiving abacavir vs. 16 (5%) receiving nevirapine died [hazard ratio (HR) 0.55; 95% confidence interval (CI) 0.24-1.25; P=0.15]; 20 receiving abacavir vs. 32 receiving nevirapine developed new or recurrent WHO 4 events or died (HR=0.60; 95% CI 0.34-1.05; P=0.07) and 48 receiving abacavir vs. 68 receiving nevirapine developed new or recurrent WHO 3 or 4 events or died (HR=0.67; 95% CI 0.46-0.96; P=0.03). Seventy-one participants (24%) receiving abacavir experienced 91 grade 4 adverse events compared with 130 events in 109 participants (36%) on nevirapine (P<0.001)., Conclusions: The clear virological/immunological superiority of nevirapine over abacavir was not reflected in clinical outcomes over 48 weeks. The inability of CD4 cell count/viral load to predict initial clinical treatment efficacy is unexplained and requires further evaluation.

Background: No data on once-daily dosing of nucleoside analogues in African children currently exist. We compared the pharmacokinetics (PK) of once- versus twice-daily lamivudine and abacavir treatment using the World Health Organization recommended weight band dosing of scored adult tablets., Methods: HIV type-1 (HIV-1)-infected Ugandan children aged 3-12 years receiving antiretroviral therapy that included lamivudine and abacavir twice daily (total 150+300 mg, 225+450 mg and 225/300+600 mg daily for 12-<20, 20-<25 and ≥25 kg, respectively) were enrolled in a crossover study. Plasma PK sampling (at 0, 1, 2, 4, 6, 8 and 12 h after observed morning intake) was performed for the twice-daily regimen at steady-state. Children were then switched to once-daily treatment with PK sampling repeated 4 weeks later (with an additional 24 h sample). Acceptability questionnaires were completed at both time points. Daily area under the curve (AUC(0-24)) and maximum concentrations (C(max)) were compared by geometric mean ratios (GMRs)., Results: A total of 41 HIV-1-infected children (median age of 7 years) and n=23, n=14 and n=4 in 12-<20, 20-<25 and ≥25 kg weight bands, respectively, were enrolled. Mean AUC(0-24) was 13.0 and 12.0 mg•h/l for once- and twice-daily lamivudine (GMR 1.09, 90% confidence intervals [CI] 0.98-1.20) and 15.3 and 15.6 mg•h/l for once- and twice-daily abacavir (GMR 0.98, 90% CI 0.89-1.08), respectively, with no difference in 3-6 versus 7-12 year olds. C(max) was 76% (lamivudine) and 64% (abacavir) higher on once-daily regimens. For both children and caregivers, once-daily dosing of lamivudine plus abacavir was highly acceptable and strongly preferred over twice-daily., Conclusions: In children aged 3-12 years, AUC(0-24) of lamivudine and abacavir were bioequivalent on once- and twice-daily regimens. Once-daily dosing of abacavir and lamivudine could provide an alternative dosing strategy for HIV-1-infected children, with high acceptability and strong preference suggesting the potential for improved adherence.

We set out to investigate whether there are clinically significant consequences when children with perinatal exposure to single-dose nevirapine are initiated on a nonnucleoside reverse transcriptase inhibitor (NNRTI) containing a highly active antiretroviral therapy (HAART) regimen. We carried out a chart and database review of 104 HIV-infected children, who had initiated HAART with an NNRTI at JCRC and were less than or equal to 5 years of age, 35 (33.7%) of whom had prior exposure to perinatal single-dose nevirapine. We studied the viral load and CD4 percentage at baseline, at week 24, and at week 48 after the start of HAART in children exposed and not exposed to perinatal single-dose nevirapine, as well as the results of genotypic resistance testing done for the children who had failed to achieve virologic suppression on HAART. At weeks 24 and 48 after initiating HAART, children not exposed to single-dose nevirapine were 3.28 times [OR = 3.28, 95% CI: (1.37 to 9.20), p = 0.0167] and 3.47 times [OR = 3.47, 95% CI: (1.28 to 9.37), p = 0.0091] more likely to achieve virologic suppression compared to children exposed to single-dose nevirapine, respectively. However, the CD4 cell response at weeks 24 and 48 was not worse in the children exposed to single-dose nevirapine. In 10 children with perinatal exposure to single-dose nevirapine, NNRTI resistance mutations, mostly K103N, Y181C, and G109A, were identified. HIV-infected children with perinatal exposure to single-dose nevirapine are less likely to achieve short-term virologic suppression when started on an NNRTI-containing regimen, when compared to those who were not exposed to it, probably because the exposure predisposes them to developing NNRTI resistance mutations.

Background: This study aimed to determine the extent of viral resistance over time among non-clade B HIV type-1-infected patients in Uganda who were maintained on first-line highly active antiretroviral therapy (HAART) following virological failure., Methods: Genotyping was performed on 16 patients with virological failure who were enrolled in an open-label randomized clinical trial of short-cycle treatment interruption., Results: All patients receiving efavirenz-containing HAART had > or =1 efavirenz resistance mutation develop during follow-up. The majority (13/15, 86%) developed lamivudine resistance during follow-up, but no thymidine analogue mutations (TAMs) developed during a median duration of virological failure of 325.5 days., Conclusions: Genotype resistance to both efavirenz and lamivudine developed early during the course of treatment after virological failure. TAMs did not emerge early despite moderate exposure time to thymidine analogues during virological failure.

The levels of IgG determined by ELISA may have limited relevance in human immunodeficiency virus (HIV)-infected adults because of non-functional antibodies. 58 HIV-1-infected and 29 HIV-uninfected Ugandan adults were immunized with conjugate vaccine (CV) followed by polysaccharide vaccine (PV) after a 2-month interval, and the opsonophagocytic killing (OPK) titers against serotype 4 or 14 pneumococcal strains as well as the levels of serotype-specific IgG in sera were determined. Significant increases were found in the OPK titers and IgG levels for both serotypes after CV vaccination irrespective of HIV status. Increases in IgG levels and OPK titers were largely dependent on the CD4(+) cell counts, except for increases in the IgG levels for serotype 4. The proportions with serum OPK titer equal to or greater than 8 were 0-4.3% for serotype 4 and 26.7-42.9% for serotype 14 before vaccination, but the proportions increased up to 43.3-86.2% for serotype 4 and 63.3-96.6% for serotype 14 in all three groups 2 months after CV vaccination. The serum OPK titers remained at levels higher than the pre-vaccination level for at least 8 months after CV vaccination. A single dose of CV could afford some protective immunity in HIV-infected African adults before the introduction of antiretroviral therapy.

Background: To estimate HIV incidence several methods have been used to discriminate recent HIV infections from long-standing infections using a single serum sample., Objective: To evaluate the performance of the anti-HIV avidity index (AI) for identifying recent HIV infections in individuals with a known date of seroconversion from Uganda, where the predominant HIV subtypes are A and D., Study Design: We selected 149 repository serum samples from Ugandan HIV-positive individuals and evaluated the AI. Specimens collected < or =6 months after seroconversion were considered as recent infections, and those collected >6 months as long-standing infections. All specimens were serotyped using a V3 peptide enzyme immunoassay., Results: The mean AI was 0.55+/-0.21 among the 108 patients with recent infections and 0.93+/-0.14 among the 41 samples from long-standing infections (p<0.0001). The AI test showed a sensitivity of 85.2% and a specificity of 85.4% at a cutoff of 0.80. No significant association was observed between serotype and the misclassification of samples by AI., Conclusions: The AI, which is inexpensive and easy-to-perform, can be useful in identifying recent HIV infections in countries where HIV-1 non-B subtypes are prevalent.

This study explores the levels of NVP and AZT resistance mutations in untreated, NVP- or AZT-treated mother-infant pairs in Uganda. PCR-amplified reverse transcriptase (RT) gene fragments derived from PBMC samples of 85 mothers (10 AZT treated, 35 NVP treated, and 40 untreated) and their 52 infected infants (5 AZT, 9 NVP, and 38 untreated) were classified as subtype A (59%), D (29%), C (3%), and recombinant forms (9%) by population sequencing. Only 16% of the NVP-treated infected mothers and infants harbored either the K103N or the Y181C at 6 weeks postdelivery. The majority of these samples (n = 107) were then analyzed using a radiolabeled oligonucleotide ligation assay (OLA) specific for K70R, K103N, and Y181C, using nonstandard bases to accommodate sequence heterogeneity. By OLA, 43% of the NVP-treated group had K103N and/or Y181C mutations in their HIV-1 population, using >0.6% cutoff based on a comparative clonal analysis of clinical isolates. Surprisingly, an equal fraction of the untreated and NVP-treated mother-infant group had the K103N mutation in their HIV-1 population in the range of 0.6-5%. These findings suggest a relatively high frequency of K103N mutation in the drug-naive, subtype A and D infected Ugandan population as compared to the very low frequency of the Y181C and K70R mutation (<0.6%). The prevalence of the K103N mutations may be related to its low fitness cost and high genetic stability. The persistence of these mutations may reduce the effectiveness of subsequent NVP use in treatment or prevention of perinatal transmission.

IL-10-producing T cells have been shown to inhibit Ag-specific CD8+ T cell responses, and may play a role in the immune dysregulation observed in HIV-1 infection. We characterized the Gag-specific IL-10 responses by CD8+ T cells in HIV-1-positive volunteers from Uganda. HIV-specific IL-10 responses were detected in 32 of 61 (52.4%) antiretroviral naive and 2 of 15 (13.3%) volunteers with a complete virologic response on antiretroviral therapy (< 400 copies/ml). The frequency of HIV-specific IL-10-positive cells was significantly higher in volunteers with advanced disease (CD4+ T cell count <200 cells/mm3; p = 0.0004), and correlated positively with plasma HIV RNA (r = 0.43, p = 0.0004). Interestingly, the frequency of Gag-specific CD107a/b-, but not IFN-gamma-, positive cells was significantly lower in individuals with detectable IL-10-positive CD8+ T cells (p = 0.004). Gag-specific IL-10-positive CD8+ T cells demonstrated a pattern of surface memory marker expression that is distinct compared with CD107a/b- and IFN-gamma-positive CD8+ T cell populations (p < 0.0001). Our study describes a distinct population of IL-10-positive CD8+ T cells that may play a role in HIV-associated immune dysfunction.

Impaired virus-specific immune responses have previously been observed with Schistosoma mansoni coinfection. We characterized Gag-specific responses in HIV-1-positive Ugandans with and without S. mansoni coinfection. We observed no significant difference in the frequency of IFN-gamma CD8+ T cells between the two groups. Interestingly, expression of CD107, a marker for cytolytic activity, was significantly lower in volunteers with S. mansoni coinfection compared with those with HIV-1 infection alone (p = 0.002). In contrast, the frequency of IL-10-positive Gag-specific CD8+ T cell responses was higher in volunteers with S. mansoni coinfection (p = 0.004). Analysis of human CMV-specific CD8+ T cell responses in the same individuals failed to reveal a similar pattern of altered CD107 and IL-10 expression. Our results suggest that S. mansoni coinfection is associated with decreased Gag-specific CD8+ cytolytic T cell responses and increased number of Gag-specific IL-10 positive CD8+ T cells. Our findings may have important implications toward the implementation of HIV preventive and therapeutic programs in Africa.

Human immunodeficiency virus (HIV) or AIDS is currently the leading cause of death in Uganda, with at least three HIV clades (subtypes) accounting for most new infections. Whether an effective vaccine formulated on viruses from a single clade will be able to protect against infection from other local clades remains unresolved. We examined the T-cell immune responses from a cohort of HIV-seropositive individuals in Uganda with predominantly clade A and D infections. Surprisingly, we observed similar frequencies of cross-clade T-cell responses to the gag, env, and nef regions. Our data suggest that the level of viral sequence variability between distinct HIV strains does not predict the degree of cross-clade responses. High sequence homologies were also observed between consensus peptides and sequences from viral isolates, supporting the use of consensus amino acid sequences to identify immunogenic regions in studies of large populations.

Human immunodeficiency virus type 1 (HIV-1) isolates derived from HIV-infected, treatment-naive Ugandan infants were propagated and tested for sensitivity to antiretroviral (ARV) drugs. Although most subtype A and D isolates displayed inhibition profiles similar to those of subtype B strains, a subtype D isolate identified as D14-UG displayed high-level resistance to nevirapine in peripheral blood mononuclear cell cultures (>2,000-fold) and in MT4 cell cultures ( approximately 800-fold) but weaker resistance to delavirdine ( approximately 13-fold) and efavirenz ( approximately 8-fold) in MT4 cell cultures. To investigate the possible mechanism for this resistance to nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs), the RT coding region in pol was sequenced and compared to the consensus RT sequence of NNRTI-resistant and NNRTI-sensitive subtype A, B, and D HIV-1 isolates. D14-UG did not contain the classic amino acid substitutions conferring NNRTI resistance (e.g., Y181C, K103N, and G190A) but did have some putative sites associated with drug resistance, I135L, T139V, and V245T. Wild-type and mutated protease-RT genes from D14-UG and an NNRTI-sensitive subtype D isolate from Uganda (D13-UG) were cloned into pNL4-3 to produce recombinant viruses and to determine the effects of the mutations on susceptibility to ARV drugs, specifically, NNRTIs. The results showed that I135L and/or V245T mutations can confer high-level resistance to nevirapine and delavirdine as well as low level cross-resistance to efavirenz. Finally, ex vivo fitness analyses suggested that NNRTI-resistant sites 135L and 245T in wild-type isolate D14-UG may reduce RT fitness but do not have an impact on the fitness of the primary HIV-1 isolate.

This study examined the emergence and prevalence of drug-resistant mutations in reverse transcriptase and protease coding regions in human immunodeficiency virus type 1 (HIV-1)-infected Ugandans treated with antiretroviral drugs (ARV). Genotypic resistance testing was performed on 50 and 16 participants who were enrolled in a cross-sectional and longitudinal observational cohort, respectively. The majority of the 113 HIV-1 PR-RT sequences were classified as subtypes A and D. Drug resistance mutations were prevalent in 52% of ARV-experienced individuals, and 17 of 27 ARV-resistant isolates had three mutations or more in reverse transcriptase. Resistance mutations in protease were less prevalent but only 17 of the 50 patients were receiving a protease inhibitor upon sample collection. Mutations conferring drug resistance were also selected in 3 of 16 participants in the longitudinal cohort, i.e., less than 8 months after the initiation of ARV treatment. Rapid emergence of ARV resistance was associated with poor adherence to treatment regimens, which was related to treatment costs. ARV resistance did, however, appear at a slightly higher prevalence in HIV-1 subtype D (21 of 33) than subtype A (7 of 25) infected individuals. Overall, this observational study suggests that ARV-resistant HIV-1 isolates are emerging rapidly in ARV-treated individual in Uganda and possibly other developing countries.

During the past year, a group has argued that unsafe injections are a major if not the main mode of HIV-1 transmission in sub-Saharan Africa. We review the main arguments used to question the epidemiological interpretations on the lead role of unsafe sex in HIV-1 transmission, and conclude there is no compelling evidence that unsafe injections are a predominant mode of HIV-1 transmission in sub-Saharan Africa. Conversely, though there is a clear need to eliminate all unsafe injections, epidemiological evidence indicates that sexual transmission continues to be by far the major mode of spread of HIV-1 in the region. Increased efforts are needed to reduce sexual transmission of HIV-1.

In the first preventative human immunodeficiency virus (HIV) vaccine study to be carried out in Africa, 40 HIV-seronegative Ugandan volunteers were randomly assigned to receive a canarypox vector containing HIV-1 clade B (env and gag-pro) antigens (ALVAC-HIV; n = 20), control vector containing the rabies virus glycoprotein G gene (n = 10), or saline placebo (n = 10). Cytotoxic T lymphocyte activity against target cells expressing clade A, B, and D antigens was assessed using standard chromium-release and confirmatory interferon-gamma enzyme-linked immunospot (ELISPOT) assays. Neutralizing antibody responses to cell line-adapted strains and primary isolates in all 3 clades were also tested. Twenty percent of vaccine recipients generated detectable cytolytic responses to either Gag or Env, and 45% had vaccine-induced HIV-specific CD8(+) T cell responses, as measured by the ELISPOT assay. In contrast, only 5% of the control group had vaccine-specific responses. Neutralizing antibodies against primary and laboratory-adapted HIV-1 clade B strains were seen in 10% and 15% of vaccine recipients, respectively, but responses against clades A and D were not detected. Although the immunogenicity of this clade B-based vaccine was low, ALVAC-HIV elicited CD8(+) T cell responses with detectable cross-activity against clade A and D antigens in a significant proportion of vaccine recipients.

Tuberculosis (TB) enhances HIV-1 replication and the progression to AIDS in dually infected patients. We employed pleural TB as a model to understand the interaction of the host with HIV-1 during active TB, at sites of Mycobacterium tuberculosis (MTB) infection. HIV-1 replication was enhanced both in the cellular (pleural compared with blood mononuclear cells) and acellular (pleural fluid compared with plasma) compartments of the pleural space. Several potential mechanisms for expansion of HIV-1 in situ were found, including augmentation in expression of tumor necrosis factor (TNF)-alpha and the HIV-1 noninhibitory beta-chemokine (MCP-1), low presence of HIV-1 inhibitory beta-chemokines (MIP-1 alpha, MIP-1 beta, and RANTES [regulated on activation, normal T expressed and secreted]), and upregulation in expression of the HIV-1 coreceptor, CCR5, by pleural fluid mononuclear cells. Thus, at sites of MTB infection, conditions are propitious both for transcriptional activation of HIV-1 in latently infected mononuclear cells, and facilitation of viral infection of newly recruited cells. These mechanisms may contribute to enhanced viral burden and dissemination during TB infection.

Objective: To characterize HIV-1 phenotypic resistance patterns and genotypic mutations among patients taking antiretroviral medications in Uganda., Methods: We reviewed charts and retrieved archived plasma specimens from patients at an AIDS specialty center in Uganda where antiretroviral therapy has been used since 1996. Phenotypic and genotypic resistance testing was done on specimens associated with a viral load of 1000 copies/ml., Results: Resistance testing of specimens was completed for 16 patients. Among 11 specimens collected before initiation of antiretroviral therapy, no phenotypic resistance or primary genotypic mutations were found. Among 8 patients taking lamivudine, phenotypic resistance was found for 9 (90%) of 10 specimens and was associated with an M184V mutation in all nine cases. Among 12 patients taking zidovudine, no phenotypic resistance and few primary mutations were found. For 6 patients who were receiving protease inhibitors, we observed no phenotypic resistance and only one primary genotypic mutation associated with resistance., Conclusions: The absence of apparent resistance among samples collected before antiretroviral therapy supports the notion that a similar approach to selection of antiretroviral therapy can generally be used against non-B subtypes. A genotypic marker of antiretroviral resistance to lamivudine in HIV-1 subtypes A, C, and D was similar to those in subtype B infections. These results suggest that the methods used for monitoring for the emergence of drug resistance in antiretroviral programs in Africa may be similar to those used in developed settings.

Active TB in HIV-1-infected subjects is associated with increased HIV-1-related immunodeficiency and mortality. We assessed plasma viral load in HIV-1-infected patients with pulmonary TB (HIV/TB) and non-TB symptomatic HIV-1-infected patients (HIV). HIV-1 load was higher in HIV/TB compared with HIV at higher CD4 counts (> 500/microl) (P < 0.01), but not at lower CD4 counts (< 500/microl). We also evaluated the status of HIV-1 gene expression in peripheral blood mononuclear cells (PBMC) and serum from HIV/TB and CD4-matched healthy HIV-infected patients (HIV/C) by reverse transcriptase-polymerase chain reaction over a range of CD4 (> 900/microl to < 200/microl). HIV-1 RNA in serum and PBMC correlated to one another, and both were markedly higher in HIV/TB compared with HIV/C with higher CD4 counts. Also, during a longitudinal study of anti-tuberculous chemoprophylaxis in HIV-1-infected patients, 10 subjects who developed TB had serologies before, at the time, and after the diagnosis of TB. These HIV/TB patients had an increase in viral load (average 2.5-fold) at the time of diagnosis of TB (P < 0.05). Overall, these data indicate that the transcriptional activity of HIV-1 is enhanced in HIV-1-infected patients with active TB, especially during early HIV-1 disease. As TB often is an early HIV-1 opportunistic infection, it may particularly favour early viral replication and dissemination, and therefore contribute to progression of HIV-1 disease.

The first prophylactic human immunodeficiency virus type 1 (HIV-1) vaccine trial in Africa, with a clade B immunogen, is currently under way in Uganda, in a region where clades A and D are endemic. The use of a B clade vaccine is based on anticipated cross-recognition of endemic strains of HIV-1 in Uganda, but, in fact, little is known about the cytotoxic T lymphocyte (CTL) responses in that region. Seventeen HIV-1-infected volunteers from Kampala, Uganda, were studied to determine the immune responses elicited by natural infection with local HIV-1 strains. Despite the presence of broad cross-clade recognition, the CTL responses to the infecting viral clade were highest in most people. Recognition of nonendemic clade B antigens was similar to that of the coendemic local clade, and, in some instances, cross-recognition of clade B was greater. Nevertheless, the degree of cross-clade cellular responses we observed lends justification to the use of clade B-based immunogens in the current phase 1 vaccine trial in Uganda.

To describe the clinical response to antituberculosis therapy in HIV-1 disease, 49 HIV-1 positive Ugandan adults (mean age 29.4 years; 68% men) with active pulmonary tuberculosis (PTB) were studied in a trial of rifampicin containing short-course antituberculosisis regimens. At presentation, 18 patients were PPD non-reactors (PPD skin test induration < 2mm), ten patients (20%) had non-cavitary lung disease. The mean CD4 lymphocyte count at presentation was 339/microliters (+/- SD 275). Among patients with abnormal baseline clinical values, the median time to resolution of fever, weight gain of 10%, increase of haemoglobin to 10g/dl and of Karnofsky performance score (KPS) to 80 occurred before sputum smear and culture conversion. Short-term survival was associated with: baseline lymphocytes < 1200/microliters, (Odds ratio (OR) 17.5), CD4+ lymphocytes < 200/microliters (OR 9.8), cavitary lung disease, (OR 0.6), atypical chest radiograph, (OR 6.7), and PPD non-reactivity, (OR 13.5), PPD non-reactivity and non-cavitary disease were associated with significantly lower CD4 lymphocyte counts. Affordable serial measurements parallel the response to therapy and predict survival in HIV-associated PTB.

Between July and October 1993, 570 19- to 22-year-old volunteers were screened for HIV-1, with a resulting seroprevalence rate of 18.3% (95% CI: 14.0%, 22.6%). A cohort of 249 HIV-1-noninfected military recruits in the Ugandan Peoples' Defense Forces was followed prospectively for up to 18 months to document rates of HIV-1 seroprevalence, seroconversion, and knowledge and attitudes related to vaccine acceptability. The HIV-1 seroincidence rate was 3.56 per 100 person-years (95% CI: 1.49, 5.62) over 309 person-years of observation. At the 3- and 12-month visits, subjects were interviewed on issues of acceptance and knowledge about vaccines, including anti-HIV vaccines in particular. More than 90% believe that HIV vaccines will not cause HIV infection, and if offered, 88% report that they would take the vaccine if they were not already infected. Nonvaccine prevention methods were considered less reliable; monogamy and condom use were considered effective by only 33.5% and 69.3% of the cohort respectively. After completing the vaccine acceptability questionnaire at the 12-month visit, subjects were offered an approved polyvalent meningococcal vaccine as an indicator of general vaccine acceptance. All subjects reported receiving at least one previous vaccination, and 95% willingly accepted the meningococcal vaccination. The Ugandan military is a stable population at substantial risk for HIV-1 infection and may be a suitable population for vaccine efficacy trials.

Little sequence information is available for human immunodeficiency virus type 1 (HIV-1) vif genes of African origin. Here we describe 37 new complete vif genes of 18 AIDS patients from Uganda and show that vif has a high in vivo genetic variability. vif proviral DNA sequences of peripheral blood cells were determined by direct sequencing of PCR products. Only 52% of the deduced Vif amino acids were absolutely conserved; when Vif sequences previously analysed were considered, only 32% of the Vif consensus sequence comprised conserved and as such possibly functionally important motifs. The high inter-individual vif variability was in contrast to a very low intra-individual variability. One patient carried a vif gene with a stable C-terminal deletion, but N-terminal truncations were not found in patients' predominant vif sequences. The vif genes analysed comprised subtypes A, D and an A/D mosaic. Phylogenetic analyses additionally showed that HIV- 1 in Uganda has spread across the boundaries of ethnic groups.

Setting: This pilot study was conducted at the Joint Clinical Research Centre (JCRC) in Kampala, Uganda, where tuberculosis (TB) is an epidemic health problem aggravated by the HIV-1 pandemic., Objective: To evaluate the feasibility of a larger phase III trial utilizing rifabutin as a substitute for rifampicin in short-course therapy for pulmonary TB., Design: Single-blind randomized trial in 50 patients with new onset smear- and culture-positive pulmonary tuberculosis and HIV-1 infection. Comparison of daily, intermittently supervised 6-month treatment regimens of rifabutin versus rifampicin, together with isoniazid, ethambutol and pyrazinamide., Results: Rifabutin- and rifampicin-containing regimens had comparable efficiency. However, rifabutin-treated patients had significantly more rapid clearance of acid-fast bacilli from sputum at 2 months (P < 0.05, Fisher exact test) and over the entire study period (P < 0.05, logrank test) than rifampicin-treated patients. The presence of cavitary disease was associated with a longer sputum conversion time for patients treated with either regimen. No major adverse events requiring dosage reduction or withdrawal of any study medication were seen in either treatment group. Mean absolute peripheral blood CD4 T lymphocyte counts increased by 28% from week 0 to week 12 in all subjects (334-427/microliters, respectively). An unexpected finding was the isolation of Mycobacterium africanum from 49% of the sputum cultures. This is the first report indicating a high prevalence of M. africanum in human TB in Uganda., Conclusion: Short-course antituberculosis regimens containing rifabutin or rifampicin are both safe and efficacious in the treatment of HIV-1 associated tuberculosis. Rifabutin-containing regimens were associated with earlier sputum smear and culture conversion.

Synthetic peptides comprising the predicted principal neutralizing determinant (PND) in new African and North American HIV-1 clones were tested in ELISA for reactivity with ninety six serum samples from asymptomatic donors in six selected localities in Uganda. Irrespective of the geographical origin of the samples, the majority of the test sera cross-reacted at high intensities with the peptides derived from the North American clone, BRT3.6 (Group B), the Ugandan clone, CUG045, (Group C), and the Romanian clone, FRMA (Group F). The frequency of reactivity of the peptides from BRT3.6, CUG045, and FRMA were within the ranges of 57-100%, 50-100%, and 57-100%, respectively, for the sera collected from these disparate localities. In contrast to these findings, the V3 peptides derived from the other Ugandan isolates showed a more restricted pattern of reactivity with the same serum samples: AUG06c (1-63%), DUG23c (2%), and DUG044 (38-87%). The results from ELISA inhibition assay indicated that the V3 peptide from BRT 3.6, CUG045, and FRMA express closely related antigenic specificities quite distinct from those in AUG06c and DUG044. The residues comprising the PND in BRT 3.6, CUG045, and FRMA appear to be well conserved in the HIV-1 subtypes prevalent in the selected Ugandan locales.