Impact of Option B+ Combination Antiretroviral Therapy on Mother-to-Child Transmission of HIV-1, Maternal and Infant Virologic Responses to Combination Antiretroviral Therapy, and Maternal and Infant Mortality Rates: A 24-Month Prospective Follow-Up Study at a Primary Health Care Clinic, in Harare, Zimbabwe

We conducted a 24-month prospective follow-up study, at a primary health care clinic in Harare, Zimbabwe, to determine cumulative mother-to-child transmission of HIV-1 (MTCT) rate and the contributions of intrauterine (IU), intrapartum (IP), and postpartum (PP) to MTCT, as well as maternal and infant mortality rates in the era of Option B⁺ combination antiretroviral therapy (cART). Plasma for viral load (VL) quantitation was obtained from 475 mothers enrolled into the study. VL was quantified at enrolment and every 6 months thereafter up to 24 months using the Cepheid GeneXpert HIV-1 Quantitative test. Dried blood spots were collected from 453 infants at birth, 4–6 weeks, 3 months, and every 3 months thereafter up to 24 months. HIV-1 infant diagnosis was conducted using the Cepheid GeneXpert HIV-1 Qualitative test. Absolute, cumulative MTCT rates and mortality rate were calculated. Seven mothers (1.55%) transmitted HIV-1 infection to their infants by 24 months. Four infants (0.88%; 95% CI 0.26–2.33%), one infant (0.22%; 95% CI 0–1.4%), and two infants (0.44%; 95% CI 0.01–1.7%) were infected IU, IP, and PP, respectively. By 24 months, 88.94% of the mothers and 80% of the infants had undetectable VL. The maternal and infant mortality rates were 0.21% and 1.78%, respectively. In the first 24 months of life, IU transmission is the major route of MTCT. The cumulative MTCT rate of 1.55% and low maternal and infant mortality rates of 0.21% and 1.78%, respectively, contribute to growing evidence that Option B⁺ cART not only drastically reduces MTCT but also maternal and infant mortality.

Mother-to-child transmission of HIV-1 and infant mortality in the first six months of life, in the era of Option B Plus combination antiretroviral therapy

OBJECTIVES

The aim of this study was to determine the contributions of intrauterine (IU), intrapartum (IP), and postpartum (PP) transmission to mother-to-child transmission of HIV-1 (MTCT) and infant mortality in the first 6 months of life, in the era of Option B Plus combination antiretroviral therapy.

METHODS

Plasma for virus load (VL) quantitation was obtained from 451 women enrolled into the study. VL was quantified using the Cepheid GeneXpert HIV-1 quantitative test. Dried blood spots were collected from 453 infants at birth, 4-6 weeks, 3 months, and 6 months. HIV-1 infant diagnosis was conducted using the Cepheid GeneXpert HIV-1 qualitative test. Absolute and cumulative MTCT rates, and the mortality rate by 6 months were calculated.

RESULTS

Seven mothers (1.55%) had transmitted HIV-1 infection to their infants by 6 months. Four infants (0.88%, 95% confidence interval (CI) 0.26-2.33%) were infected IU, one infant (0.22%, 95% CI 0-1.4%) was infected IP, and two infants (0.44%, 95% CI 0.01-1.7%) were infected PP. The infant mortality rate was 0.88% (95% CI 0.26-2.33%).

CONCLUSIONS

In the first 6 months of life, in the era of Option B Plus combination antiretroviral therapy, IU transmission is the major route of MTCT. The cumulative MTCT rate of 1.55% in a breastfeeding population contributes to growing evidence that complete elimination of MTCT is possible.

Antimicrobial susceptibility patterns amongst group B streptococci from women in Harare, Zimbabwe

As part of a larger study of vaginal pathogens in women in Harare, we have examined the antimicrobial susceptibility patterns of 130 isolates of group B streptococci (GBS). These organisms are important because of their association with preterm labour, premature rupture of membranes and neonatal sepsis. All of the isolates in Harare were fully sensitive to beta-lactams, with an MIC(90) for ampicillin of 0.38 mg/l, but five isolates were resistant in vitro to erythromycin, and each of these had an MIC >4 mg/l. Seven isolates showed resistance to clindamycin. Some isolates showed an intermediate sensitivity to gentamicin, but the great majority were resistant to this antibiotic. Studies in developed countries have shown that an intervention strategy, using intrapartum chemoprophylaxis, is effective in reducing the incidence of complications of GBS colonization in pregnant women. Our data suggest that ampicillin would be a suitable antibiotic for use in an intervention programme of intrapartum chemoprophylaxis in Harare.

Bayesian network analysis of resistance pathways against HIV-1 protease inhibitors

Interpretation of Human Immunodeficiency Virus 1 (HIV-1) genotypic drug resistance is still a major challenge in the follow-up of antiviral therapy in infected patients. Because of the high degree of HIV-1 natural variation, complex interactions and stochastic behaviour of evolution, the role of resistance mutations is in many cases not well understood. Using Bayesian network learning of HIV-1 sequence data from diverse subtypes (A, B, C, F and G), we could determine the specific role of many resistance mutations against the protease inhibitors (PIs) nelfinavir (NFV), indinavir (IDV), and saquinavir (SQV). Such networks visualize relationships between treatment, selection of resistance mutations and presence of polymorphisms in a graphical way. The analysis identified 30N, 88S, and 90M for nelfinavir, 90M for saquinavir, and 82A/T and 46I/L for indinavir as most probable major resistance mutations. Moreover we found striking similarities for the role of many mutations against all of these drugs. For example, for all three inhibitors, we found that the novel mutation 89I was minor and associated with mutations at positions 90 and 71. Bayesian network learning provides an autonomous method to gain insight in the role of resistance mutations and the influence of HIV-1 natural variation. We successfully applied the method to three protease inhibitors. The analysis shows differences with current knowledge especially concerning resistance development in several non-B subtypes.

A pilot study to assess the immunologic and virologic efficacy of generic nevirapine, zidovudine and lamivudine in the treatment of HIV-1 infected women with pre-exposure to single dose nevirapine or short course zidovudine and their spouses in Chitungwiza, Zimbabwe

OBJECTIVE

A pilot study to assess effectiveness of generic Nevirapine (NVP)+Zidovudine (AZT)+Lamivudine (3TC) as potent antiretroviral therapy (ART) in women exposed to either SD NVP or short course (SC) AZT through participation in prevention of mother-to-child transmission of HIV-1 (pMTCT) interventions, and their spouses.

DESIGN

A pilot study of antiretroviral treatment of adults with AIDS.

SETTING

Primary health care clinics; Seke North and St Mary's in Chitungwiza, Zimbabwe.

SUBJECTS

Women with pre-exposure to SD NVP or SC AZT and their spouses with CD4 count < 200 cells/

INTERVENTIONS

Generic AZT/3TC twice daily plus NVP daily for the first 14 days and then twice a day thereafter, administered to the cohort.

MAIN OUTCOME MEASURES

The baseline median CD4 count for women and men was 128.5 and 119.0 cells/ microL respectively. The geomean virus load was similar for the women and men. At weeks 16, 24 and 48, 82.8%, 85.1% and 73.8% had < 400 copies/ml of HIV RNA respectively. Only at 16 weeks, was the proportion of women (75.9%) with undetectable virus significantly lower than that for men (93.9%), p = 0.031. Median CD4 count for both men and women increased significantly, p < 0.001. There were no significant differences in virologic responses between the women with pre-exposure to SD NVP and SC AZT. The mean adherence for women and men was similar, > 98%.

CONCLUSION

Women showed a significantly reduced response top ART relative to men only at 16. However, prior exposure to SD NVP for PMTCT was no more likely to negatively influence responses to ART than use of SC AZT.

Chlamydia trachomatis in symptomatic and asymptomatic men: detection in urine by enzyme immunoassay

BACKGROUND

Infection with Chlamydia trachomatis is known to be a common cause of urethritis and cervicitis. The standard methods of detection require the collection of intra-urethral and/or cervical swabs, which may be submitted for culture, antigen detection or nucleic acid amplification. The collection of swabs is suitable only within the context of a health care facility. Recent reports have indicated that antigen detection can be used with urine specimens, and because these can be self-collected, this may be particularly useful for the detection of asymptomatic carriage.

OBJECTIVE

To determine the sensitivity and specificity of urine antigen assays in the detection of chlamydial infection in men.

SETTING

Two groups of men were investigated; men with urethritis attending clinics or private practitioners, and healthy adult men enrolled into either urban or rural HIV prevention projects.

METHODS

Urine samples from men in both groups were collected and assayed for the presence of chlamydial antigen using a commercial enzyme immunoassay (EIA) kit. For symptomatic men an intra-urethral swab was also collected and assayed for antigen detection using a commercial EIA. For asymptomatic men, a ligase chain reaction was carried out on the same urine sample.

RESULTS

The prevalence of chlamydial antigen in symptomatic men was 15% (39/257), and in asymptomatic men was 4% (15/349). The sensitivity and specificity of urine EIA for symptomatic men was 87% and 83% respectively. For asymptomatic men, the sensitivity of urine EIA was 86%, and the specificity was 100%.

CONCLUSION

Urine EIA is a relatively inexpensive method for the detection of chlamydial infections in men. The true specificity in symptomatic men may be higher, as the "gold standard" that we used may give false negative results. Antigen EIA for examination of urine specimens from community surveys of asymptomatic men may be particularly useful because of the low cost of assays, and because urine samples can be self-collected without discomfort to study subjects. The prevalence of C. trachomatis that we describe here is consistent with other studies of chlamydial epidemiology in Zimbabwe.

Characterization of the HIV-1 specific humoral immune response during highly active antiretroviral therapy (HAART)

Plasma samples from 19 patients were analyzed for HIV-1 directed humoral immune responses prior to and 1 year after initiation of HAART. Eight of the subjects were classified as virologic successes, defined by a >100-fold decrease in viral load (VL) over the 1-year study period and a final VL <500 copies/ml. The eleven HAART failures were defined as subjects with <10-fold decrease in VL. At study entry (before HAART), VL and CD4 counts were similar between the two groups. Humoral immune responses before therapy and after 1 year of therapy were measured by V3 peptide antibody binding titers and neutralization of HIV-1 MN and four subtype B clinical isolates. Before HAART, neutralizing antibody titers to the clinical isolates and HIV(MN), as well as HIV V3 envelope binding titers to several V3 peptides, were significantly higher among treatment successes compared with treatment failures. After 1 year on HAART, neutralization declined in titer and narrowed in specificity among the HAART successes. In contrast, a significant increase in both neutralizing titer and breadth was seen among HAART failures.

Associations of CCR5, CCR2, and stromal cell-derived factor 1 genotypes with human immunodeficiency virus disease progression in patients receiving nucleoside therapy

Genotype data for CCR5, CCR2, and stromal cell-derived factor 1 (SDF-1) were obtained from 354 human immunodeficiency virus type 1 (HIV-1)-positive subjects who were being treated with nucleosides. Associations with HIV-1 load, HIV syncytium-inducing (SI) phenotype, CD4 cell count, and disease progression were analyzed. No differences in HIV-1 load or CD4 cell count were observed between wild type (+) and variant genotypes. Changes from non-SI to SI viral phenotype were more frequent in heterozygotes with a 32-bp deletion (Delta32) in the CCR5 gene than in + homozygotes (40% vs. 7%; P=.01). In a multivariate analysis, heterozygous CCR5 Delta32 was associated with reduced hazard of progression (hazard ratio, 0.32; P=.02). Subjects homozygous for the SDF-1 3'A variant had more-rapid disease progression (P=.008). The SDF-1 homozygous 3'A variant was related to more-rapid disease progression, and CCR5 Delta32 was associated with reduced rates of hazard for disease progression in nucleoside-treated subjects.

Nelfinavir, efavirenz, or both after the failure of nucleoside treatment of HIV infection

BACKGROUND

The optimal antiretroviral treatment for patients who have human immunodeficiency virus (HIV) viremia despite treatment with nucleoside reverse-transcriptase inhibitors (nucleoside analogues) remains uncertain. We studied treatment with regimens that combined two nucleoside analogues, at least one of which was new, with the protease inhibitor nelfinavir, the nonnucleoside reverse-transcriptase inhibitor efavirenz, or both.

METHODS

The study included 195 patients who had been treated with nucleoside analogues only, and had a plasma HIV type 1 (HIV-1) RNA level of at least 500 copies per milliliter. Patients were randomly assigned to receive, in addition to two nucleoside analogues, nelfinavir, efavirenz, or nelfinavir plus efavirenz. The primary end point was a plasma HIV-1 RNA level of less than 500 copies per milliliter at week 16. A secondary end point was the composite of the HIV-1 RNA levels measured at weeks 40 and 48.

RESULTS

At week 16 and at weeks 40 and 48, the proportions of patients in whom a plasma HIV-1 RNA level of less than 500 copies per milliliter was achieved were, respectively, 81 percent and 74 percent in the nelfinavir-plus-efavirenz group, 69 percent and 60 percent in the efavirenz group, and 64 percent and 35 percent in the nelfinavir group. Quadruple therapy resulted in a higher rate of viral suppression in both the short term (P=0.03) and the long term (P=0.001) than did triple therapy with nelfinavir. Triple therapy with efavirenz conferred a higher rate of long-term suppression than triple therapy with nelfinavir (P=0.004). Quadruple therapy also achieved a higher rate of virologic suppression than triple therapy with efavirenz (P=0.008).

CONCLUSIONS

In HIV-infected patients previously treated with nucleoside analogues, treatment with nelfinavir plus efavirenz and at least one new nucleoside analogue achieves a higher rate of viral suppression than do regimens with nucleoside analogues and nelfinavir or efavirenz alone.

Genotypic correlates of a virologic response to stavudine after zidovudine monotherapy

Prior evidence suggests that resistance to zidovudine (ZDV) confers some degree of cross-resistance to stavudine (d4T), but no genotypic correlates of clinical d4T susceptibility and resistance exist. To identify the genotypic correlates of a virologic response to d4T, reverse transcriptase (RT) sequencing of archived plasma HIV isolates was performed on 31 subjects who received d4T monotherapy in the AIDS Clinical Trials Group 302 study, all of whom received more than 3 years of ZDV monotherapy. Baseline characteristics and all RT mutations were analyzed for impact on virologic suppression. Eight of 31 subjects (27%) achieved a virologic response of greater than 0.3 log reduction in plasma HIV RNA after 8 weeks of d4T. Responders were more likely to have lower median baseline viral loads (4.2 vs. 4.7; p =.01) and a trend toward fewer ZDV-associated mutations (median: 1 vs. 2; p =.09). No subject with greater than one ZDV mutation had a virologic response to d4T. Seven of the 8 responders had only a K70R mutation at baseline. We conclude that in patients with prior ZDV treatment, those with only one ZDV mutation, particularly at position 70, can still get reasonable virologic activity from d4T. Those with more mutations are not likely to have much benefit.

Virologic and CD4 cell response to zidovudine or zidovudine and lamivudine following didanosine treatment of human immunodeficiency virus infection

To optimize nucleoside reverse transcriptase inhibitor (nRTI) antiretroviral therapy, 137 subjects who had been treated with didanosine monotherapy for more than 3 years in the AIDS Clinical Trials Group (ACTG) 175 study were randomized to zidovudine and didanosine (dual therapy) or zidovudine, didanosine, and lamivudine (triple therapy). Evaluation of early (8 week) change in HIV plasma RNA demonstrated that addition of lamivudine and zidovudine provided significantly greater virologic suppression compared to the addition of zidovudine alone (mean decrease of 1.27 vs. 0.74 log(10) copies/ml, n = 108, p = 0.007). Both dual and triple therapy provided significant long-term decreases (from study entry to mean at Weeks 40 and 48) in HIV plasma RNA: 0.62 and 0.86 log(10) copies/ml, respectively (n = 110). However, the difference between treatments was not significant (p = 0.16). At 48 weeks, 26% of subjects starting study treatment had <500 copies/ml of plasma HIV RNA. The CD4 count response was greater at 4 weeks for triple versus dual therapy: a mean increase of 51 vs. 12 CD4 cells/ml(3) (n = 126, p = 0.039). The difference at Weeks 40 and 48 was not significant (a 22 cell increase vs. a 1 cell decrease, n = 129, p = 0.41). Zidovudine and didanosine treatment, with or without lamivudine, was well tolerated and only 2 of 137 (1.5%) of study participants developed an AIDS-defining event over 48 weeks.

Effect of lamivudine in HIV-infected persons with prior exposure to zidovudine/didanosine or zidovudine/zalcitabine

Nucleoside analog-based regimens remain an integral component of combination therapy for use in both antiretroviral treatment-naive and experienced HIV-infected patients. To further define treatment responses to new antiretroviral therapy in patients with long-term experience to dual nucleoside analog therapy (zidovudine [ZDV] plus didanosine [ddI] or ZDV plus zalcitabine [ddC]), 325 subjects derived from the AIDS Clinical Trials Group (ACTG) 175 trial were randomized to three different combination regimens: (1) continuation of ZDV + ddI or ZDV + ddC (continuation arm), (2) addition of 3TC to ZDV + ddI or ZDV + ddC (addition arm), or (3) a switch to ZDV + 3TC therapy (switch arm). Both the addition and switch arms sustained significantly greater short-term (baseline to week 4) mean CD4+ cell count increases compared with the continuation arm (+36, +28 versus -4 cells/mm3; p = 0.012) and long-term CD4+ cell count responses (baseline to weeks 40/48: +32, +19 versus -9 cells/mm3; p = 0.003). Superior short-term (baseline to week 8) mean decreases in plasma HIV RNA (p < 0.001) were achieved by both the addition and switch arms (0.53 log10 and 0.54 log10 copies/ml, respectively) compared with the continuation arm (0.13 copies/ml) whereas no differences in long-term virologic suppression were observed (p = 0.30). At week 48, no differences were observed in the proportions of subjects who had HIV RNA levels below 500 copies/mL: 18% of subjects in each treatment arm (3-way p = 1.0). Overall, the treatments were well tolerated and only nine subjects (3%) died or developed one or more AIDS-defining events. While this study confirms the intrinsic antiretroviral activity of 3TC, only modest marker changes and limited short-term viral suppression are seen with incremental addition of the drug. The current approach of using 3TC in maximally suppressive regimens is preferred.

Differences between women and men in adverse events and CD4+ responses to nucleoside analogue therapy for HIV infection. The Aids Clinical Trials Group 175 Team

OBJECTIVE

To prospectively examine differences in baseline characteristics and study outcomes between HIV-infected women and men during a clinical trial of nucleoside analogue therapy.

METHODS

ACTG 175 randomized HIV-infected patients with CD4+ counts between 200 and 500 cells/mm3 to one of four nucleoside analogue regimens: zidovudine (ZDV), didanosine (ddI), ZDV + ddI, or ZDV + zalcitabine (ddC). Differences in time to first dose modification, voluntary withdrawal, development of toxicity and symptomatology, and AIDS progression were compared by gender.

RESULTS

The study included 438 women and 2029 men. Baseline values of HIV RNA plasma concentrations were significantly lower for women (0.3 log10) than men in a subset of patients in whom assays were taken and this difference persisted after adjustment for CD4+ count. Women reported reducing dosage and discontinue ddI-containing regimens more frequently than men did; adjustment for weight did not completely explain this difference. Women were at lower risk than men for progression to a study endpoint (19% of women versus 24% of men; p <.0001). Among those antiretroviral-naive study subjects receiving ZDV, men were four times more likely to progress to a study endpoint than women.

CONCLUSIONS

Differences in pretreatment characteristics and on study experiences were demonstrated between women and men enrolled in this clinical trial. The suggestion of a gender difference in response to ZDV monotherapy by antiretroviral-naive study subjects and the lower baseline values for HIV RNA in women compared with those in men provides evidence for gender differences in the relationship between virus replication, CD4+ decline, and responses to nucleoside analogue therapy.

Virologic and CD4+ cell responses to new nucleoside regimens: switching to stavudine or adding lamivudine after prolonged zidovudine treatment of human immunodeficiency virus infection. ACTG 302 Study Team. AIDS Clinical Trials Group

Clinical benefit of zidovudine alone in the treatment of HIV infection wanes after several years, with decreasing CD4+ cell numbers and increasing HIV RNA in plasma. To develop treatment strategies following prolonged zidovudine treatment, 92 subjects from the AIDS Clinical Trials Group (ACTG) 175 study after a median of 3.6 years of zidovudine monotherapy were randomized to treatment with stavudine or zidovudine and lamivudine. Evaluation of long-term changes, the average of 40- and 48-week HIV plasma RNA, demonstrated that lamivudine and zidovudine provided significantly greater virologic suppression compared with stavudine (mean decrease 0.70 versus 0.18 1og10 copies/ml,p = 0.003). Twenty-nine percent of zidovudine plus lamivudine recipients had HIV RNA levels below 500 copies per milliliter at 48 weeks as compared with 4% of stavudine recipients (p = 0.02). Both regimens significantly increased CD4+ cell numbers, the means of weeks 40 and 48 rose to 49 and 36 CD4+ cells per cubic millimeter among zidovudine plus lamivudine and stavudine recipients, respectively. Treatments were well tolerated and only 3 of 92 subjects died or developed AIDS within 48 weeks. In zidovudine-experienced subjects, addition of lamivudine resulted in significantly decreased plasma HIV RNA levels at 48 weeks compared with treatment with stavudine alone.

HIV type 1 envelope subtype C sequences from recent seroconverters in Zimbabwe

HIV-1 envelope sequence patterns have implications for virus cell tropism and for the development of an effective vaccine. To identify the sequence characteristics of recently transmitted HIV-1 isolates in southern Africa, we sequenced the V3-V5 envelope regions of 24 male seroconverters in Harare, Zimbabwe. Each of the sequences clustered with previously reported subtype C isolates and there was a mean 17% intersequence pairwise genetic distance between the Zimbabwean isolates. Three isolates were syncytium inducing (SI). One of the SI isolates had an unusual GIGK crown and a deletion at codon 23; one had the codon 23 deletion alone; and one had a high net positive charge in the V3 loop. The extensive genetic diversity within the envelope of subtype C HIV-1 isolates must be considered in vaccine development. Further analysis of subtype C SI isolates and site-directed mutagenesis experiments are required to determine the molecular basis of SI activity in global HIV-1 isolates.

Report of sexually transmitted diseases by HIV infected men during follow up: time to target the HIV infected?

OBJECTIVES

To compare the rate of self reported sexually transmitted diseases (STDs) among HIV infected men with men who remained HIV negative during follow up of a Harare male factory cohort.

METHODS

Male factory workers were offered enrolment and behavioural data were collected at entry then every 6 months, along with HIV testing. Self report of STDs was used to calculate incidence per 100 person years. Cox proportional hazards models examined independent risk factors for STDs, with hazard ratios (HRs).

RESULTS

At entry 20% of men were HIV infected and 11% reported STDs in the previous year. A total of 2777 (82%) of 3383 men enrolled were followed at least once. Compared with men who remained HIV negative, seroconverters had the highest incidence of STDs (16.8 per 100 person years; IRR = 3.3, 95% CI = 2.5-4.3); men enrolled HIV positive also reported higher STD incidence (14.5 per 100 person years, IRR = 2.8; 95% CI 2.3-5.5). Among HIV positive men, the only independent risk factor for report of urethral discharge was history of multiple partners (HR = 10, 95% CI 1.4-73.2).

CONCLUSION

HIV positive men reported threefold higher incidence of STDs than HIV negative men, many related to high risk sexual behaviour.

Adherence as a particular issue with protease inhibitors

Suboptimal therapeutic doses of HIV protease inhibitors lead to the emergence of drug resistance and reduced drug efficacy. It is imperative, then, that patients and clinicians alike are fully educated about the importance of patients taking all the pills in these new, admittedly complex, antiretroviral regimens. With protease inhibitors especially, missing doses and/or taking drug holidays or partial doses will mean the rapid emergence of HIV isolates that are resistant to these drugs.

Both serum HIV type 1 RNA levels and CD4+ lymphocyte counts predict clinical outcome in HIV type 1-infected subjects with 200 to 500 CD4+ cells per cubic millimeter. AIDS Clinical Trials Group Study 175 Virology Study Team

To evaluate HIV-1 RNA and CD4+ cell responses to therapy as predictors of clinical progression and to evaluate levels and trends of these markers prior to clinical failure, HIV-1 RNA measurements were retrospectively obtained on subjects who progressed to AIDS or death and a random sample of subjects who did not. Samples were taken from AIDS Clinical Trials Group Study 175, a randomized trial comparing nucleoside analog therapies in subjects with CD4+ cell counts of between 200 and 500 cells/mm3. HIV-1 RNA and CD4+ cell count independently predicted clinical progression. Risk of subsequent progression is best captured by the change to the last measured value for CD4+ cell count and the area under the curve minus baseline, a measure of viral replication over time, for HIV-1 RNA. Subjects who failed had lower CD4+ cell counts, greater rates of CD4+ cell decline, and higher HIV-1 RNA levels, but not greater rates of HIV-1 RNA increase than subjects who did not. Subjects who maintained more than 200 CD4+ cells/mm3 and fewer than 10,000 copies of HIV-1 RNA per milliliter had low risk of progression. During the first few months of therapy, treatments are best monitored by regular HIV-1 RNA and less frequent CD4+ cell measurements. Thereafter, both markers should be monitored on a similar schedule to identify rapidly declining CD4+ cell counts, or adverse levels of either. These results further delineate the prognostic significance of HIV-1 RNA and CD4+ cell count and should help to better define their utility in the practice setting.

Efavirenz- and adefovir dipivoxil-based salvage therapy in highly treatment-experienced patients: clinical and genotypic predictors of virologic response

OBJECTIVE

To determine the impact of prior nonnucleoside reverse transcriptase inhibitor (NNRTI) therapy, genotypic resistance, and other variables on response to efavirenz (EFV)- and adefovir dipivoxil (ADV)-based salvage therapy.

DESIGN

Retrospective clinical cohort study.

SETTING

One university and one community-based HIV clinic.

STUDY SUBJECTS

All 33 patients who were coenrolled in both the EFV and ADV expanded access programs.

INTERVENTIONS

Patients received EFV 600 mg/day and ADV 120 mg/day in addition to other antiretroviral agents.

OUTCOME MEASURE

HIV viral load (<500 copies/ml) at 12 and 24 weeks.

RESULTS

10 of 33 (30%) patients at 12 weeks and 8 of 33 (24%) patients at 24 weeks had viral loads <500 copies/ml. Prior NNRTI use and a history of any NNRTI-associated mutations predicted failure. Patients with Y181C or G190A single mutations had an initial greater magnitude of viral load suppression than those with K103N, but this advantage was short lived. No one with any NNRTI mutations responded with a viral load <500 copies/ml at 12 or 24 weeks.

CONCLUSIONS

EFV/ADV-based salvage yielded viral load suppression at 24 weeks in 42% (8 of 19) of patients who were highly NRTI and protease inhibitor experienced but NNRTI naive. NNRTI-experienced study subjects had a poor response regardless of the specific NNRTI resistance mutation they harbored.

Antiretroviral therapy in adults: updated recommendations of the International AIDS Society-USA Panel

OBJECTIVE

To update recommendations for antiretroviral therapy for adult human immunodeficiency virus type 1 (HIV-1) infection, based on new information and drugs that are available.

PARTICIPANTS

A 17-member international physician panel with antiretroviral research and HIV patient care experience initially convened by the International AIDS Society-USA in December 1995.

EVIDENCE

Available clinical and basic science data including phase 3 controlled trials; data on clinical, virologic, and immunologic end points; research conference reports; HIV pathogenesis data; and panel expert opinion. Recommendations were limited to therapies available (US Food and Drug Administration approved) in 1999.

CONSENSUS PROCESS

The panel assesses new research reports and interim results and regularly meets to consider how the new data affect therapy recommendations. Recommendations are updated via full-panel consensus. Guidelines are presented as recommendations if the supporting evidence warrants routine use in the particular situation and as considerations if data are preliminary or incomplete but suggestive.

CONCLUSIONS

The availability of new antiretroviral drugs has expanded treatment choices. The importance of adherence, emerging long-term complications of therapy, recognition and management of antiretroviral failure, and new monitoring tools are addressed. Optimal care requires individualized management and ongoing attention to relevant scientific and clinical information in the field.

Delayed-type hypersensitivity to recombinant HIV envelope glycoprotein (rgp160) after immunization with homologous antigen

Delayed-type hypersensitivity (DTH) responses to intradermal recombinant HIV envelope glycoprotein (rgp160) may assess cell-mediated immune responses to HIV envelope. In three studies, DTH and lymphocyte proliferation responses to rgp160 were obtained in a total of 106 HIV-seropositive subjects with CD4+ counts >400 cells/mm3. Several subjects participated in more than one study. Before immunization, DTH responses were seen in 5 of 56 (9%) of HIV-infected study subjects. After immunization with an alum-adjuvanted experimental rgp160 vaccine, DTH responses were seen in 46 of 52 (89%). Using in vitro lymphocyte proliferation activity (LPA) to rgp160 as an indication of cellular immune response, skin testing has a sensitivity of 0.75 (95% confidence Interval [CI], 0.59-0.88) and a specificity of 0.84 (95% CI, 0.72-0.92). Biopsy samples of skin that had tested positive confirmed the presence of a DTH reaction with a predominance of CD4+ T cells in the perivascular, inflammatory infiltrate. Skin testing before and after immunization with candidate AIDS vaccines could provide a simple method in the field to assess new cell mediated immune responses.

Syphilis serology and HIV infection in Harare, Zimbabwe

OBJECTIVE

To determine the reliability of serological tests in detecting syphilis in a factory worker cohort and examine the impact of concurrent HIV infection on serological tests for syphilis.

METHOD

Reactions to non-treponemal and treponemal antigens were tested using sera from a cohort of 3401 factory workers in Harare, Zimbabwe. The participants consented to regular testing for syphilis, by VDRL, and HIV using two ELISAs. All sera from men who were VDRL positive, and a random sample of VDRL negative sera, were tested by RPR, TPHA, and where appropriate FTA-Abs. From the results, men were defined as having no syphilis, active syphilis, incident syphilis, historic syphilis, or giving biological false positive reactions.

RESULTS

709 sera were examined from 580 men. There were 78 cases of active syphilis in the cohort, giving a prevalence of 2.3%, and the seroincidence was 0.25 per 100 person years of follow up. The prevalence of HIV in the cohort was 19.8%. There was a strong association between syphilis, whether active, incident or historic, and HIV seropositivity. With both HIV positive and negative sera the negative predictive values of VDRL and RPR were > 99.9% while the positive predictive value for VDRL (30%) was lower than for RPR (39%). Biological false positive reactions were detected in 0.5% of the cohort, with in most cases a transient rise in VDRL titres up to < 1/16. Higher false positive titres occurred in five men, each of whom was HIV positive.

CONCLUSIONS

The VDRL is reliable in detecting possible cases of syphilis even in a community with a high prevalence of heterosexually transmitted HIV. There is need, however, for confirmatory tests. The prevalence of syphilis in this cohort is very low in comparison with other countries in southern Africa, but is consistent with recent data from Harare. Despite a strong association between syphilis and HIV it was clear that syphilis could not be counted as a major factor fueling the HIV epidemic in Zimbabwe.

The contribution of assay variation and biological variation to the total variability of plasma HIV-1 RNA measurements. The Women Infant Transmission Study Clinics. Virology Quality Assurance Program

OBJECTIVES

To assess the specific contributions of assay variation and biological variation to the total variation of plasma HIV-1 RNA measured by the Roche Monitor assay and the extent to which batch assays reduced both assay variability and total variability compared with real-time determinations.

DESIGN

A retrospective analysis of data obtained from three trials conducted by the Adult and Pediatric AIDS Clinical Trials Groups (ATCG), the Women and Infants Transmission Study (WITS) and the NIAID-sponsored Virology Quality Assurance Program.

METHODS

Within-subject variation was assessed from stored, serially collected plasma samples from 663 subjects enrolled in the ACTG and WITS studies. Interassay and intra-assay variation were estimated from two of the clinical trials and 22 laboratories that participated in a quality assurance program and were used to estimate the effect of real-time testing on total variation.

RESULTS

The total variation (standard deviation) from a random effects model was 0.26 log10 RNA copies/ml. The estimated interassay variation was 0.08 log10 and intra-assay variation was 0.12 log10 RNA copies/ml. Biological variation accounted for 56-80% of total variation. The effect of real-time testing compared with batch testing was minimal.

CONCLUSION

Our estimates of total within-subject HIV-1 RNA variation support the current recommendation to obtain at least two specimens, preferably obtained less than 2 weeks apart, for viral RNA measurement before starting therapy. The major contribution of biological variation to the total variation supports the use of real-time HIV-1 RNA assays, provided that consistent specimen collection procedures are followed and acceptable assay proficiency is maintained.

Serum level of maternal human immunodeficiency virus (HIV) RNA, infant mortality, and vertical transmission of HIV in Zimbabwe

Maternal human immunodeficiency virus (HIV) RNA load, vertical transmission of subtype C HIV, and infant mortality were examined in 251 HIV-seropositive women and their infants in Zimbabwe. Demographic characteristics, health and medical histories, serum HIV RNA loads, and CD4+ lymphocyte counts for mothers were examined by logistic regression analysis to determine significant risk factors and their odds ratios for transmission and infant mortality. Tenfold (1 log10) incremental increases in maternal HIV RNA were associated with a 1.9-fold increase (95% confidence interval [CI], 1.2-2.9) in transmission and a 2.1-fold increase (95% CI, 1.3-3.5) in infant mortality (P<.01). Maternal CD4 cell counts and demographic and medical characteristics were not significant predictors of transmission. However, maternal CD4 cell counts below the median (400/mm3) were significantly associated with infant mortality (P=. 035, Fisher's exact test). The maternal level of serum HIV is an important determinant of vertical transmission and infant mortality in subtype C infection in Zimbabwe.

Primary subtype C HIV-1 infection in Harare, Zimbabwe

Heterosexual transmission of HIV-1 is widespread in Southern Africa. Heteroduplex mobility assays (HMA) and phylogenetic analyses of V3-V5 envelope (env) gene sequences demonstrate that subtype C predominates in Zimbabwe. To elucidate factors contributing to the epidemic in Zimbabwe, clinical and virologic characteristics of recently acquired subtype C HIV-1 infection among 21 men and 1 woman were determined. In 12 of 19 men providing clinical histories, a sexually transmitted infection preceded serologic evidence of HIV-1, and 14 of 19 men complained of rash or fever before seroconversion. Quantitative p24 antigen levels, reverse transcriptase activity, and HIV RNA levels of 22 viral isolates correlated with in vitro infectivity in peripheral blood mononuclear cells (p < .05). Biologic phenotype assessed in MT-2 cells demonstrated that 3 of 22 isolates (14%) were syncytia inducing (SI) and the remaining 19 nonsyncytium inducing (NSI). Early growth of virus in culture was associated with increased plasma HIV RNA levels, decreased CD4 cell levels, and SI virus. Recent subtype C HIV-1 infection through heterosexual transmission in Zimbabwe demonstrated clinical and virologic features consistent with reports of seroconversion to subtype B viruses.

Detection of Kaposi's sarcoma-associated herpesvirus in peripheral blood cells in human immunodeficiency virus infection: association with Kaposi's sarcoma, CD4 cell count, and HIV RNA levels

Kaposi's sarcoma-associated herpesvirus (KSHV) DNA, consistently found in Kaposi's sarcoma (KS) tissues, was sought in peripheral blood mononuclear cells (PBMCs) of HIV-infected individuals. To determine quantitative relationships between the presence of KSHV DNA in PBMCs, CD4 cell counts, plasma HIV RNA levels, and the development of KS, we designed a cross-sectional study of prospectively collected PBMC samples from ongoing cohort studies. PBMCs were collected from 142 HIV-seropositive individuals in California, 7 of whom had a clinical diagnosis of KS. KSHV sequences were detected in extracted PBMC DNA by nested polymerase chain amplification using two nonoverlapping primer sets. KSHV DNA was detected in PBMCs of 5 of 7 (71%) subjects with KS and in 18 of 135 (13%) HIV-infected subjects without KS. Among HIV-seropositive individuals without KS, detection of KSHV was more common in men than women (19 versus 4%, p = 0.01) and was associated with lower mean CD4 percent (14.8 versus 20.7% CD4 cells, p = 0.03), lower mean CD4 cell count (244 versus 334 CD4 cells/microl, p = 0.05), and higher geometric mean plasma HIV RNA (4.83 versus 4.03 1og10 copies/ml, p = 0.0002). Semiquantitative analysis found 5 to 15,625 copies of KSHV per microgram of PBMC DNA with increased plasma HIV RNA levels and a trend toward increased subsequent development of KS in subjects with higher KSHV loads. The association of the presence of KSHV DNA in PBMCs with lower CD4 cell counts and higher plasma HIV RNA provides evidence of a relationship between immunosuppression, HIV replication, and KSHV expression.

Neuromuscular function in HIV infection: analysis of a placebo-controlled combination antiretroviral trial. AIDS Clinical Group 175/801 Study Team

OBJECTIVE

To determine the frequency of peripheral neuropathy and myopathy in HIV-infected subjects enrolled in a combination antiretroviral treatment trial.

DESIGN AND METHODS

AIDS Clinical Trial Group (ACTG) protocol 175 was a multicenter, double-blind, placebo-controlled, clinical trial. A total of 2467 subjects were randomized to one of four single or combination regimens, containing zidovudine (ZDV), didanosine (ddl), zalcitabine (ddC), and their respective placebos. Site investigators reported peripheral neuropathy, and the diagnosis of distal symmetrical neuropathy (DSP) was established by the study authors. Myalgia, muscle weakness and creatine phosphokinase (CPK) were prospectively assessed in a subset of the antiretroviral-naive cohort (n = 1067).

RESULTS

Of 222 site diagnoses of neuropathy, 109 (49%) were DSP. There was a significant difference between treatment arms for rate of DSP and time to first grade 2 or higher DSP (ZDV-ddC, 6%; ZDV, 4%; ZDV-ddl, 4%; ddl, 3%; P = 0.029). Age and Karnofsky score were significant predictors of DSP. Fifty-six (54%) out of 104 patients with DSP remained on study medication at full (n = 29) or reduced (n = 27) dose within 6 months of developing neuropathy. There was no significant difference between treatment arms in the rate of myalgia or muscle weakness. The median CPK of subjects on ZDV-ddC was significantly higher than other study treatments, although CPK levels did not correlate with symptoms of myopathy. Only six subjects were diagnosed with myopathy during the study (one ZDV-ddl, one ZDV-ddC, and four ddl).

CONCLUSIONS

DSP and myopathy may occur with current dosing regimens of combination antiretroviral therapy, and should be diagnosed using stringent criteria. ZDV-ddC was associated with the highest rate of DSP, although features of myopathy were not significantly different between treatment regimens.

A 6-basepair insert in the reverse transcriptase gene of human immunodeficiency virus type 1 confers resistance to multiple nucleoside inhibitors

While many point mutations in the HIV-1 reverse transcriptase (RT) confer resistance to antiretroviral drugs, inserts or deletions in this gene have not been previously characterized. In this report, 14 RT inhibitor-treated patients were found to have HIV-1 strains possessing a 6-basepair insert between codons 69 and 70 of the RT gene. Known drug resistance mutations were also observed in these strains, with T215Y appearing in all strains. Genotypic analysis indicated that the inserts had substantial nucleotide variability that resulted in relatively restricted sets of amino acid sequences. Linkage of patients' treatment histories with longitudinal sequencing data showed that insert strains appeared during drug regimens containing ddI or ddC, with prior or concurrent AZT treatment. Drug susceptibility tests of recombinant patient isolates showed reduced susceptibility to nearly all nucleoside RT inhibitors. Site- directed mutagenesis studies confirmed the role of the inserts alone in conferring reduced susceptibility to most RT inhibitors. The addition of AZT-associated drug resistance mutations further increased the range and magnitude of resistance. These results establish that inserts, like point mutations, are selected in vivo during antiretroviral therapy and provide resistance to multiple nucleoside analogs.

Estimating HIV incidence from age-specific prevalence data: comparison with concurrent cohort estimates in a study of male factory workers, Harare, Zimbabwe

OBJECTIVE

To compare HIV incidence estimates from cross-sectional age-specific prevalence data with concurrent cohort estimates and to examine the sensitivity of the estimates to changes in age-categorization and survivorship assumptions.

METHODS

Two previously described methods of estimating HIV incidence from cross-sectional prevalence data - the cumulative incidence and survival (CIS) and constant prevalence (CP) methods - are applied using data from a study of male factory workers in Harare, Zimbabwe. The methods are applied under two alternative groupings of the HIV prevalence data and under alternative survivorship assumptions: (a) Weibull distribution providing the best fit to the HIV prevalence data using the CIS method; (b) Weibull distribution matching data from an HIV natural history cohort study in Uganda; and (c) survivorship pattern as in (b) with survival periods reducing with increasing age at infection. Age-specific, age-standardized and cumulative HIV incidence estimates are calculated. The results are compared with concurrent longitudinal estimates from 3 years of follow-up of the Harare cohort (1993-1995).

RESULTS

Age-standardized HIV incidence was estimated at 2.02 per 100 man years (95% CI, 1.57-2.47) in the cohort study. There was evidence of recent variability in HIV incidence in these data. Estimates from the cross-sectional methods ranged from 1.98 to 2.74 per 100 man years and were sensitive to changes in age-categorization of the HIV prevalence data and changes in survivorship assumptions. The cross-sectional estimates were higher at central ages and lower at older ages than the cohort estimates. The age-specific estimates from the CIS method were less sensitive to changes in age grouping than those from the CP method.

CONCLUSIONS

HIV incidence remains high in Harare. Incidence estimates broadly consistent with cohort estimates can be obtained from single-round cross-sectional HIV prevalence data in established epidemics - even when the underlying assumption of stable endemic prevalence is not fully met. Estimates based on cross-sectional surveys should therefore be explored when reliable longitudinal estimates cannot be obtained. More data on post-HIV infection survivorship distributions in sub-Saharan Africa would facilitate the improvement of estimates of incidence based on cross-sectional surveys.

Antiretroviral therapy for HIV infection in 1998: updated recommendations of the International AIDS Society-USA Panel

OBJECTIVE

To provide recommendations for antiretroviral therapy based on information available in mid-1998.

PARTICIPANTS

An international panel of physicians with expertise in antiretroviral research and care of patients with human immunodeficiency virus (HIV) infection, first convened by the International AIDS Society-USA in December 1995.

EVIDENCE

The panel reviewed available clinical and basic science study results (including phase 3 controlled trials; clinical, virologic, and immunologic end point data; data presented at research conferences; and studies of HIV pathophysiology); opinions of panel members were also considered. Recommendations were limited to drugs available in mid-1998.

CONSENSUS PROCESS

Panel members monitor new clinical research reports and interim results. The full panel meets regularly to discuss how the new information may change treatment recommendations. Updated recommendations are developed through consensus of the entire panel at each stage of development.

CONCLUSIONS

Accumulating data from clinical and pathogenesis studies continue to support early institution of potent antiretroviral therapy in patients with HIV infection. A variety of combination regimens show potency, expanding choices for initial regimens for individual patients. Plasma HIV RNA assays with increased sensitivity are important in monitoring therapeutic response; however, more data are needed to determine precisely the HIV RNA levels that define treatment failure. Long-term adverse drug effects are beginning to emerge, requiring ongoing attention. Some issues regarding optimal long-term approaches to antiretroviral management are unresolved. The increased complexity in HIV management requires ongoing monitoring of new data for optimal treatment of HIV infection.

HIV-1 reverse transcriptase codon 215 mutation in plasma RNA: immunologic and virologic responses to zidovudine. The AIDS Clinical Trials Group Study 175 Virology Team

Treatment of HIV infection with zidovudine (ZDV) may select for changes in the genetic sequence of the viral reverse transcriptase (RT) that imparts drug resistance. The presence of a 2-bp mutation at codon 215 of RT (from threonine to phenylalanine or tyrosine) was assessed in plasma viral RNA in 85 subjects treated with ZDV in the AIDS Clinical Trials Group (ACTG) 175 virology substudy. Median CD4 cell numbers, HIV plasma RNA levels, and infectious titers of virus were significantly different over 56 weeks of treatment among 58 subjects with the wild-type threonine at codon 215 virus at study entry compared with the 27 subjects with mutations to phenylalanine or tyrosine (MUT) virus. Thirty percent (13 of 44 subjects) with wild-type virus at study entry developed a new codon 215 mutation. Genotypic resistance at codon 215 in plasma HIV RNA is associated with the subsequent immunologic and virologic failure of ZDV monotherapy in subjects with 200 to 500 CD4 cells/mm3.

Variability and prognostic values of virologic and CD4 cell measures in human immunodeficiency virus type 1-infected patients with 200-500 CD4 cells/mm(3) (ACTG 175). AIDS Clinical Trials Group Protocol 175 Team

Virologic measurements are increasingly used to evaluate prognosis and treatment responses in human immunodeficiency virus (HIV) type 1 infection. Markers of HIV-1 replication, including infectious HIV-1 titer from peripheral blood mononuclear cells, serum HIV-1 p24 antigen, plasma HIV-1 RNA, CD4 cell numbers, and viral syncytium-inducing (SI) phenotype, were determined in 391 virology substudy participants in AIDS Clinical Trials Group study 175. The subjects had 200-500 CD4 cells/mm3. All markers of viral replication significantly correlated with one another and were inversely related to CD4 cell number. Disease progression to an AIDS-defining event or death or loss of >50% of CD4 cells was associated with infectious HIV-1 titer (P < .001), HIV-1 RNA (P < .001), and HIV-1 p24 antigen (P = .007). In multivariate proportional hazards models, p24 antigen was never significant when HIV-1 RNA level was included. In a model containing infectious HIV-1 titer (P = .038), HIV-1 RNA (P < .001), SI phenotype (P < .001), and CD4 cell number (P = .18), only the virologic parameters remained significantly associated with progression.

Changes in virologic markers as predictors of CD4 cell decline and progression of disease in human immunodeficiency virus type 1-infected adults treated with nucleosides. AIDS Clinical Trials Group Protocol 175 Team

The associations of CD4 cell count, plasma human immunodeficiency virus (HIV) type 1 RNA, infectious HIV titer in peripheral blood mononuclear cells, immune complex-disrupted (ICD) p24 antigen, and MT-2 assays with measures of disease progression after drug treatment were assessed in a subset of patients enrolled in AIDS Clinical Trials Group Study 175. Baseline plasma RNA levels and changes in RNA values at weeks 8 or 56 were more important predictors of disease progression than were baseline or changes in CD4 cell counts. Each 10-fold lower HIV RNA concentration at baseline and each 10-fold decrease in HIV RNA between baseline and week 8 was associated with increases of 49-61 CD4 cells/mm3 at weeks 56 and 104. In multivariate analyses, neither baseline values nor changes in infectious HIV titer nor ICD p24 antigen concentrations were associated with long-term changes in CD4 cell count. Plasma HIV-1 RNA appears to be the best predictor of long-term CD4 cell count responses and disease progression.

Polymerase chain reaction detection of Haemophilus ducreyi DNA

OBJECTIVES

To develop a polymerase chain reaction (PCR) method to detect Haemophilus ducreyi DNA in cultured isolates and clinical material.

METHODS

Primers specific to the H ducreyi 16s rRNA gene were synthesised. PCR conditions were optimised and products were verified by restriction endonuclease digestion and agarose gel electrophoresis.

RESULTS

The method was able to detect all 28 H ducreyi strains tested; specificity was demonstrated using lysates of 12 related organisms. Applied to clinical samples from genital ulcer swabs obtained in Harare, Zimbabwe, H ducreyi DNA was detected in repeated assays in 35 clinical samples.

CONCLUSION

PCR amplification using primers from the 16s rRNA gene may be a useful alternative to culture for the detection of H ducreyi and the diagnosis of chancroid.

Use of changes in plasma levels of human immunodeficiency virus type 1 RNA to assess the clinical benefit of antiretroviral therapy

Data from 1330 human immunodeficiency virus type 1 (HIV-1)-infected patients enrolled in seven antiretroviral treatment trials were analyzed to characterize the clinical benefit of treatment-mediated reductions in plasma HIV-1 RNA levels. The risk of a new AIDS-defining event or death was reduced proportionally to the magnitude of the reduction of the HIV-1 RNA level during the first 6 months of therapy. Pretherapy HIV-1 RNA levels were prognostic independently of on-therapy levels. In addition, the reduction in risk associated with any given reduction of the level of HIV-1 RNA did not vary by pretherapy level. Having either a reduction in HIV-1 RNA level or an increase in CD4+ lymphocyte count, or both, was associated with a delay in clinical disease progression. This indicates that patient prognosis should be assessed using both HIV-1 RNA and CD4+ lymphocyte responses to therapy.

Meta-analysis of five randomized controlled trials comparing continuation of zidovudine versus switching to didanosine in HIV-infected individuals

A meta-analysis of the original data from 2411 patients in the ACTG 116A, ACTG116B/117, ACTG175, BMS010 and CTN002 trials was conducted to improve the estimate of the effect of switching from zidovudine to didanosine on rates of clinical progression, to better quantify the rates of neurological events (including AIDS dementia and peripheral neuropathy) and to examine the effects of switching from zidovudine to didanosine among women and racial subgroups. In total, 1012 patients received zidovudine therapy, 557 received high-dose didanosine and 842 received didanosine. The median duration of follow-up was 15 months. Ninety-one percent of patients were male, 78% were white, mean age was 36.5 years. The median CD4 count was 195 cells/mm3 (range: 0-762) and the median duration of prior zidovudine therapy was 14 months (range: 0.1-94). There were 336 deaths and 686 new AIDS-defining illnesses (ADIs) or deaths. After stratification by study and adjusting for baseline CD4 count and presence of an AIDS diagnosis prior to baseline, the relative risks of death associated with switching from zidovudine to high-dose didanosine or to didanosine were 0.94 (P = 0.64) and 0.77 (P = 0.07), respectively. The relative risks of a new ADI or death associated with switching from zidovudine to high-dose didanosine and didanosine were 0.78 (P = 0.01) and 0.66 (P = 0.0001), respectively. There were 21 documented cases of AIDS dementia complex (ADC) during the entire follow-up period. The rates per 100 person years of follow-up were 0.70, 0.65 and 0.41 for the zidovudine, high-dose didanosine and didanosine arms, respectively. There were no significant differences in risks of ADC between treatment arms (zidovudine versus high-dose didanosine: P = 0.30, zidovudine versus didanosine: P = 0.97, didanosine versus high-dose didanosine: P = 0.41). Our data confirm a clinical benefit and CD4 increase associated with a switch from zidovudine to didanosine therapy. No statistical differences were detected between doses of didanosine with respect to survival or progression to a new ADI or death. Furthermore, there was no statistical difference in the frequency of ADC between treatment arms.

Divergent transcriptional regulation among expanding human immunodeficiency virus type 1 subtypes

The current AIDS pandemic represents the uneven spread of multiple genetically related subtypes (A to J) of human immunodeficiency virus type 1 (HIV-1). Notably, HIV-1 E in southeast Asia and HIV-1 C in sub-Saharan Africa are expanding faster and are likely of greater global significance than the HIV-1 B subtype prevalent in the United States and Europe. While many studies have focused on genetic variation among structural genes, we chose to conduct a comparative analysis of the long terminal repeats of HIV-1 E and HIV-1 C isolates and report subtype-specific differences in enhancer copy numbers and sequences, as well as divergent activation in response to the cellular transcriptional activators Rel-p65 and NFATc and viral Tat. This study is the first to identify functional distinctions in promoter architecture between HIV-1 subtypes and raises the possibility that regulatory divergence among the subtypes of HIV-1 has occurred. Divergent transcriptional regulation may explain some of the epidemiologically observed differences in transmission and pathogenesis and underscores the need for further comparative analysis of HIV-1 regulation.

Sequence and drug susceptibility of subtype C reverse transcriptase from human immunodeficiency virus type 1 seroconverters in Zimbabwe

Naturally occurring human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) variability has implications for the success of antiretroviral therapy. We determined the sequence of the polymerase-coding region of RT from virus isolates from 12 Zimbabwean individuals recently infected with HIV-1. The 12 RT sequences differed from the consensus B RT sequence at 10.5% of nucleotides and 5.8% of amino acids. Susceptibility testing of five isolates to zidovudine, didanosine, lamivudine, and nevirapine demonstrated susceptibilities similar to those of wild-type subtype B isolates. Phylogenetic analysis of 40 HIV-1 RT sequences, including the 12 Zimbabwean subtype C sequences, 11 subtype B sequences, and the 17 remaining published non-subtype B sequences showed sufficient intrasubtype RT sequence variation to differentiate subtype A, B, C, and D isolates. Five recently reported subtype C RT sequences from India grouped with the Zimbabwean subtype C sequences but had significantly less intraisolate sequence variation. Both intra- and intersubtype RT comparisons were notable for extraordinarily high ratios of synonymous to nonsynonymous differences. Although substitutions in the HIV-1 RT gene are limited by functional constraints, variation between RT sequences demonstrates phylogenetic relationships that parallel env and gag gene variation.

Antiretroviral therapy for HIV infection in 1997. Updated recommendations of the International AIDS Society-USA panel

OBJECTIVE

To provide current recommendations for antiretroviral therapy for human immunodeficiency virus (HIV) disease.

PARTICIPANTS

The original International AIDS Society-USA 13-member panel representing international expertise in antiretroviral research and care of patients with HIV infection.

EVIDENCE

The following were considered: Newly available clinical and basic science study results, including phase 3 controlled trials; clinical, virological, and immunologic end-point data; interim analyses of studies presented at national and international research conferences; studies of HIV pathophysiology; and expert opinions of panel members. Recommendations were limited to the drugs available in mid 1997.

PROCESS

The full panel met on a regular basis (July 1996, September 1996, November 1996, January 1997, and April 1997) since the publication of its initial recommendations in mid 1996 to review new research reports and interim results. The panel discussed whether and how new information changed its initial recommendations. The recommendations contained herein were determined by group consensus.

CONCLUSIONS

New data have provided a stronger rationale for earlier initiation of more aggressive therapy than previously recommended and reinforce the importance of careful selection of initial drug regimen for each patient for optimal long-term clinical benefit and adherence. The plasma viral load is a crucial element of clinical management for assessing prognosis and the effectiveness of therapy, and such testing must be done properly. Treatment failure is most readily indicated by a rising plasma HIV RNA level and should be confirmed prior to a change of treatment. Therapeutic approaches must be updated as new data, particularly on the long-term clinical effect of aggressive antiretroviral treatment, continue to emerge.

Antiretroviral therapy for human immunodeficiency virus infection in 1997

It has become clear that the acquired immunodeficiency syndrome follows continuous replication of the human immunodeficiency virus (HIV) and a decrease in immune capability, most obviously a decline in the number of CD4 lymphocytes. An understanding of key elements in the infectious life cycle of HIV has led to the development of potent antiretroviral drugs selectively targeting unique reverse transcriptase and protease enzymes of the virus. Completed clinical trials have shown that antiretroviral therapy for HIV infection, begun early, reduces viral replication and reverses the decline in CD4 lymphocyte numbers. Recent studies of combination therapies have shown that decreases in plasma HIV viremia to low levels and sustained increases in CD4 cell numbers are associated with longer survival. Potent combination regimens including protease inhibitors and non-nucleoside reverse transcriptase inhibitors suppress detectable viral replication and have demonstrated clinical benefits in patients with advanced disease. Progress in antiretroviral therapy and methods to monitor responses to treatment are providing new hope in the treatment of HIV infection.

An evaluation of dipstick-dot immunoassay in the detection of antibodies to HIV-1 and 2 in Zimbabwe

There is a need, in many developing countries, for simple and inexpensive HIV serology tests for use at the district level of health care. The Programme for Appropriate Technology in Health has developed a simple dipstick ELISA to detect antibodies to HIV-1 and 2, at a cost considerably lower than current ELISAs, which requires no specialized washing or reading equipment. In order to evaluate this dipstick under local conditions we used a panel of 546 sera selected from frozen stocks maintained by the Zimbabwe AIDS Prevention Project in Harare, Zimbabwe. Prior to storage, the sera had been tested by Abbott recombinant peptide HIV-1 and 2 ELISA and Enzygnost synthetic peptide HIV-1 and 2 ELISA. The panel included sera that were positive by both (including symptomatics and asymptomatics), negative by both, and sera showing discrepant test results. The panel was not representative of a "normal' batch of sera in Zimbabwe, and in particular included an abnormally high number of sera showing discrepant results. Thawed sera were retested using the Abbott recombinant peptide HIV-1 and 2 ELISA and concurrently with the synthetic peptide ICL-Dipstick ELISA. Both the sensitivity and specificity of the ICL Dipstick exceeded 99% when using sera that were positive or negative in all 3 plate ELISAs as the gold standard. When using sera that gave discrepant results between the two pre-storage ELISAs, most results with the ICL Dipstick concurred with findings from other test systems, including Western blot and p24 antigen detection. Considering the accuracy, low cost and case of operation of the ICL Dipstick ELISA, this test can be recommended for use for the rapid detection of antibodies to HIV at district level in developing countries.

Antimicrobial resistance in gonococci isolated from patients and from commercial sex workers in Harare, Zimbabwe

The objective is to compare antibiotic resistance amongst gonococci isolated from different patient groups in Harare, Zimbabwe. Antimicrobial susceptibilities of Neisseria. gonorrhoeae were determined by disc sensitivity tests. The MICs for penicillin, kanamycin, ceftriaxone, norfloxacin and ciprofloxacin were determined using E-test strips. There were 147 isolates from symptomatic men, 47 isolates from symptomatic women, 29 isolates from asymptomatic women and 41 isolates from female commercial sex workers. A total of 119 (45%) isolates were PPNG and 23 (16%) non-PPNG isolates had a penicillin MIC > 0.64 mg/l. Over 90% of isolates were resistant to TMP/SMX and 16% were resistant to tetracycline. Resistance was uncommon against kanamycin (6%), erythromycin (2%) or ceftriaxone ( < 1%). For kanamycin, the MIC90 was 32 mg/l, for ceftriaxone the MIC90 was < 0.032 mg/l for non-PPNG and < 0.064 mg/l for PPNG. For norfloxacin and ciprofloxacin the MIC90 was < 0.064 mg/l for both PPNG and non-PPNG. Isolates from the commercial sex workers showed a significantly increased prevalence of PPNG, of penicillin-tolerant non-PPNG and of tetracycline resistance. Four of the 41 isolates from sex workers showed multiple resistance (to penicillin, TMP/SMX, tetracycline and kanamycin) compared to 1/223 isolates from other groups (OR = 24.0). Antimicrobial resistance is common amongst gonococci in Harare, especially with isolates from commercial sex workers. In order for STD treatment to be implemented as an effective strategy in HIV control, continued monitoring of resistance patterns is essential.

Risk factors for HIV infection at enrollment in an urban male factory cohort in Harare, Zimbabwe

Between March 1993 and March 1995, volunteers at 40 Harare factories were interviewed regarding sociodemographic characteristics and behavior; HIV serostatus was also determined. Among 2,691 men enrolled, HIV prevalence was 19.4%. Prevalence rose 2-fold with each year of age in young men (< 23 years). In a multivariate logistic model that included sociodemographic and behavioral variables, compared with those between 25 and 44 years, both younger men (OR = 0.51) and older men (OR = 0.49) were less likely to be HIV positive. In addition, marriage (OR = 2.01), history of sexually transmitted disease (STD) (genital ulcer, OR = 4.93, urethral discharge OR = 1.75), multiple partners (OR = 1.58), cash payment for sex (OR = 2.55) and condom use (OR = 1.35) were all independent risk factors for HIV infection. Home ownership conferred lower risk. Self-reported condom use was seen as a marker of correct personal risk assessment men who used condoms reported more risk behavior and had a higher prevalence of HIV, either because condom use was not consistent or because infection occurred prior to adoption of condoms. This study confirms established risk factors in a general population sample not selected for high risk of HIV infection. It suggests rapid acquisition of infection among young men and the importance of marriage (and separation of spouses) as correlates of HIV infection.

A trial comparing nucleoside monotherapy with combination therapy in HIV-infected adults with CD4 cell counts from 200 to 500 per cubic millimeter. AIDS Clinical Trials Group Study 175 Study Team

BACKGROUND

This double-blind study evaluated treatment with either a single nucleoside or two nucleosides in adults infected with human immunodeficiency virus type 1 (HIV-1) whose CD4 cell counts were from 200 to 500 per cubic millimeter.

METHODS

We randomly assigned 2467 HIV-1--infected patients (43 percent without prior antiretroviral treatment) to one of four daily regimens: 600 mg of zidovudine; 600 mg of zidovudine plus 400 mg of didanosine; 600 mg of zidovudine plus 2.25 mg of zalcitabine; or 400 mg of didanosine. The primary end point was a > or = 50 percent decline in the CD4 cell count, development of the acquired immunodeficiency syndrome (AIDS), or death.

RESULTS

Progression to the primary end point was more frequent with zidovudine alone (32 percent) than with zidovudine plus didanosine (18 percent; relative hazard ratio, 0.50; P<0.001), zidovudine plus zalcitabine (20 percent; relative hazard ratio, 0.54; P<0.001), or didanosine alone (22 percent; relative hazard ratio, 0.61; P<0.001). The relative hazard ratios for progression to an AIDS-defining event or death were 0.64 (P=0.005) for zidovudine plus didanosine, as compared with zidovudine alone, 0.77 (P=0.085) for zidovudine plus zalcitabine, and 0.69 (P=0.019) for didanosine alone. The relative hazard ratios for death were 0.55 (P=0.008), 0.71 (P=0.10), and 0.51 (P=0.003), respectively. For zidovudine plus zalcitabine, the benefits were limited to those without previous treatment.

CONCLUSIONS

Treatment with zidovudine plus didanosine, zidovudine plus zalcitabine, or didanosine alone slows the progression of HIV disease and is superior to treatment with zidovudine alone. Antiretroviral therapy can improve survival in patients with 200 to 500 CD4 cells per cubic millimeter.

The relation of virologic and immunologic markers to clinical outcomes after nucleoside therapy in HIV-infected adults with 200 to 500 CD4 cells per cubic millimeter. AIDS Clinical Trials Group Study 175 Virology Study Team

BACKGROUND

We studied measures of human immunodeficiency virus (HIV) replication, the viral phenotype, and immune function (CD4 cell counts) and the relation of changes in these indicators to clinical outcomes in a subgroup of patients in a controlled trial of early antiretroviral treatment for HIV, the AIDS Clinical Trials Group Study 175.

METHODS

The 391 subjects, each of whom entered the study with a single screening CD4 cell count of 200 to 500 per cubic millimeter, were randomly assigned to receive zidovudine alone, didanosine alone, zidovudine plus didanosine, or zidovudine plus zalcitabine. Plasma concentrations of HIV RNA were assessed in 366 subjects, and viral isolates from 332 subjects were assayed for the presence of the syncytium-inducing phenotype.

RESULTS

After eight weeks, the mean (+/-SE) decrease from base line in the concentration of HIV RNA, expressed as the change in the base 10 log of the number of copies per milliliter, was 0.26+/-0.06 for patients treated with zidovudine alone, 0.65+/-0.07 for didanosine alone, 0.93+/-0.10 for zidovudine plus didanosine, and 0.89+/-0.06 for zidovudine plus zalcitabine (P<0.001 for each of the pairwise comparisons with zidovudine alone). Multivariate proportional-hazards models showed that higher base-line concentrations of plasma HIV RNA, less suppression of plasma HIV RNA by treatment, and the presence of the syncytium-inducing phenotype were significantly associated with an increased risk of progression to the acquired immunodeficiency syndrome and death. After adjustment for these measures of viral replication and for the viral phenotype, CD4 cell counts were not significant predictors of clinical outcome.

CONCLUSIONS

Both the risk of the progression of HIV disease and the efficacy of antiretroviral therapy are strongly associated with the plasma level of HIV RNA and with the viral phenotype. The changes in the plasma concentration of HIV RNA predict the changes in CD4 cell counts and survival after treatment with reverse-transcriptase inhibitors.

Antiretroviral therapy for HIV infection in 1996. Recommendations of an international panel. International AIDS Society-USA

OBJECTIVE

To provide clinical recommendations for antiretroviral therapy for human immunodeficiency virus (HIV) disease with currently (mid 1996) available drugs. When to start therapy, what to start with, when to change, and what to change to were addressed.

PARTICIPANTS

A 13-member panel representing international expertise in antiretroviral research and HIV patient care was selected by the international AIDS Society-USA.

EVIDENCE

Available clinical and basic science data, including phase 3 controlled trials, clinical endpoint data, virologic and immunologic endpoint data, interim analyses, studies of HIV pathophysiology, and expert opinions of panel members were considered. Recommendations were limited to drugs available in mid 1996.

PROCESS

For each question posed, 1 or more member(s) reviewed and presented available data. Recommendations were determined by group consensus (January 1996); revisions as warranted by new data were incorporated by group consensus (February-May 1996).

CONCLUSIONS

Recent data on HIV pathogenesis, methods to determine plasma HIV RNA, clinical trial data, and availability of new drugs point to the need for new approaches to treatment. Therapy is recommended based on CD4+ cell count, plasma HIV RNA level, or clinical status. Preferred initial drug regimens include nucleoside combinations; at present protease inhibitors are probably best reserved for patients at higher progression risk. For treatment failure or drug intolerance, subsequent regimen considerations include reasons for changing therapy, available drug options, disease stage, underlying conditions, and concomitant medication(s). Therapy for primary (acute) infection, high-risk exposures to HIV, and maternal-to-fetal transmission are also addressed. Therapeutic approaches need to be updated as new data continue to emerge.

Polyethylene glycol-modified interleukin-2 and thymosin alpha 1 in human immunodeficiency virus type 1 infection

The safety and antiviral effects of polyethylene glycolated interleukin-2 (PEG-IL-2) and thymosin alpha 1 in addition to zidovudine were studied in 12 human immunodeficiency virus (HIV)-infected subjects with 50-250 CD4 T cells/mm3. PEG-IL-2 was administered by intravenous infusions every 2 weeks at 10(6) IU/m2 for 20 weeks. Thymosin alpha 1 was administered subcutaneously at 400 microgram/m2 after four doses of PEG-IL-2, escalating to 1600 microgram/m2 weekly for an additional 2 months. Significant elevations of CD4 T cell numbers of 30%-40% were seen after PEG-IL-2 infusions, but no additional increase in CD4 cell count was observed with thymosin alpha 1. Virologic monitoring by polymerase chain reaction quantitation of proviral DNA and plasma RNA and p24 antigen assays showed no evidence of increased HIV activation during PEG-IL-2 or thymosin alpha 1 therapy. Patients tolerated both PEG-IL-2 and thymosin alpha 1 without significant toxicities.

Drug resistance and heterogeneous long-term virologic responses of human immunodeficiency virus type 1-infected subjects to zidovudine and didanosine combination therapy. The AIDS Clinical Trials Group 143 Virology Team

Plasma human immunodeficiency virus (HIV) type 1 RNA levels, CD4 lymphocyte changes, and drug resistance were studied in HIV-infected patients with 200-500 CD4 lymphocytes/microL who received zidovudine and didanosine combination therapy for 2 years. Among 35 patients, 10 had sustained and 16 had transient > 10-fold reductions in HIV RNA: 9 did not have 10-fold HIV RNA reductions. Only patients with sustained HIV suppression maintained increased CD4 cell counts for 2 years (370 to 501 cells/microL; P = .006). Patients with transient HIV suppression were more likely to develop drug-resistant HIV strains (12/16 vs. 5/19, P = .01) and reverse transcriptase (RT) mutations (4.5 vs. 2.5/strain; P = .02) than were patients with sustained or no HIV suppression. Zidovudine resistance occurred with RT mutations at codons 41, 67, 70, 215, and 219. Multidrug resistance occurred with mutations at codons 62, 75, 77, 116, and 151. Mutations occurred at codons 60, 68, 118, 210, and 228 in > or = 4 patients each. Heterogeneity exists among individual virologic responses to zidovudine and didanosine combination therapy. HIV resistance mechanisms during combination therapy appear more complex than reported with monotherapy.