Richard Marlink

Barriers to Antiretroviral Adherence for Patients Living with HIV Infection and AIDS in Botswana

Background: Botswana has the highest rate of HIV infection in the world, estimated at 36% among the population aged 15‐49 years. To improve antiretroviral (ARV) treatment delivery, we conducted a cross‐sectional study of the social, cultural, and structural determinants of treatment adherence. Methods: We used both qualitative and quantitative research methodologies, including questionnaires and interviews with patients receiving ARV treatment and their health care providers to elicit principal barriers to adherence. Patient report and provider estimate of adherence (≥95% doses) were the primary outcomes. Results: One hundred nine patients and 60 health care providers were interviewed between January and July 2000; 54% of patients were adherent by self‐report, while 56% were adherent by provider assessment. Observed agreement between patients and providers was 68%. Principal barriers to adherence included financial constraints (44%), stigma (15%), travel/migration (10%), and side effects (9%). On the basis of logistic regression, if cost were removed as a barrier, adherence is predicted to increase from 54% to 74%. Conclusions: ARV adherence rates in this study were comparable with those seen in developed countries. As elsewhere, health care providers in Botswana were often unable to identify which patients adhere to their ARV regimens. The cost of ARV therapy was the most significant barrier to adherence.

Human Immunodeficiency Virus Type 1 Subtypes Differ in Disease Progression

At least 10 different genetic human immunodeficiency virus type 1 (HIV-1) subtypes (A-J) are responsible for the AIDS pandemic. Much of the understanding of HIV-1 disease progression derives from studies in the developed world where HIV infection is almost exclusively subtype B. This has led many to question whether the properties and consequences of HIV-1 infection can be generalized across subtypes that afflict the majority of infected persons in the developing world. From 1985 to 1997, a prospective study of registered female sex workers in Senegal tracked the introduction and spread of HIV-1 subtypes A, C, D, and G. In clinical follow-up, the AIDS-free survival curves differed by HIV-1 subtype. Women infected with a non-A subtype were 8 times more likely to develop AIDS than were those infected with subtype A (hazard ratio=8.23; P=. 009), the predominant subtype in the study. These data suggest that HIV-1 subtypes may differ in rates of progression to AIDS.

Association between Virus-Specific T-Cell Responses and Plasma Viral Load in Human Immunodeficiency Virus Type 1 Subtype C Infection

ABSTRACT Virus-specific T-cell immune responses are important in restraint of human immunodeficiency virus type 1 (HIV-1) replication and control of disease. Plasma viral load is a key determinant of disease progression and infectiousness in HIV infection. Although HIV-1 subtype C (HIV-1C) is the predominant virus in the AIDS epidemic worldwide, the relationship between HIV-1C-specific T-cell immune responses and plasma viral load has not been elucidated. In the present study we address (i) the association between the level of plasma viral load and virus-specific immune responses to different HIV-1C proteins and their subregions and (ii) the specifics of correlation between plasma viral load and T-cell responses within the major histocompatibility complex (MHC) class I HLA supertypes. Virus-specific immune responses in the natural course of HIV-1C infection were analyzed in the gamma interferon (IFN-γ)-enzyme-linked immunospot assay by using synthetic overlapping peptides corresponding to the HIV-1C consensus sequence. For Gag p24, a correlation was seen between better T-cell responses and lower plasma viral load. For Nef, an opposite trend was observed where a higher T-cell response was more likely to be associated with a higher viral load. At the level of the HLA supertypes, a lower viral load was associated with higher T-cell responses to Gag p24 within the HLA A2, A24, B27, and B58 supertypes, in contrast to the absence of such a correlation within the HLA B44 supertype. The present study demonstrated differential correlations (or trends to correlation) in various HIV-1C proteins, suggesting (i) an important role of the HIV-1C Gag p24-specific immune responses in control of viremia and (ii) more rapid viral escape from immune responses to Nef with no restraint of plasma viral load. Correlations between the level of IFN-γ-secreting T cells and viral load within the MHC class I HLA supertypes should be considered in HIV vaccine design and efficacy trials.

Five-year outcomes of initial patients treated in Botswana's National Antiretroviral Treatment Program

Background: Antiretroviral treatment (ART) initiatives have now been established in many sub-Saharan African countries showing early benefits. To date, few results are available concerning long-term clinical outcomes in these treatment programs. Methods: Response to ART is described in the first HIV-1C-infected adults enrolled in the Botswana Antiretroviral Treatment Program in 2002. Data analysis was conducted on available longitudinal data up to 1st April 2007. Results: Six hundred thirty-three severely immunodeficient patients with a median CD4+ cell count of 67 cells/μl were initiated on non-nucleoside reverse transcriptase inhibitor-based combination ART and followed for a median of 41.9 months. The median CD4+ cell count increases were 169, 302, and 337 cells/μl at 1, 3, and 5 years, respectively. The percentages of patients with a viral load of less than 400 copies/ml at 1, 3, and 5 years were 91.3, 90.1, and 98.3%, respectively. Seventy-five percent of patients did not miss a single, or missed only one, monthly ART pickup per year with a mean pickup rate of 92.5%. The Kaplan–Meier survival estimates [95% confidence interval (CI)] at 1, 3, and 5 years were 82.7% (81.2 and 84.3%), 79.3% (77.6 and 81.0%), and 79.0% (77.3 and 80.7%), respectively. At 6 months, the risk of treatment modification for anemia was 6.94% (5.9 and 8.0%) for cutaneous hypersensitivity reactions, 1.3% (0.8 and 1.7%), and 1.1% (0.7 and 1.6%) for hepatotoxicity. Conclusion: This initial group of adults on ART in Botswana had excellent sustained immunologic, virologic, and clinical outcomes for up to 5 years of follow-up with low mortality among those surviving into the second year of ART.

Human immunodeficiency virus type 1 subtype C molecular phylogeny: consensus sequence for an AIDS vaccine design?

ABSTRACT An evolving dominance of human immunodeficiency virus type 1 subtype C (HIV-1C) in the AIDS epidemic has been associated with a high prevalence of HIV-1C infection in the southern African countries and with an expanding epidemic in India and China. Understanding the molecular phylogeny and genetic diversity of HIV-1C viruses may be important for the design and evaluation of an HIV vaccine for ultimate use in the developing world. In this study we analyzed the phylogenetic relationships (i) between 73 nonrecombinant HIV-1C near-full-length genome sequences, including 51 isolates from Botswana; (ii) between HIV-1C consensus sequences that represent different geographic subsets; and (iii) between specific isolates and consensus sequences. Based on the phylogenetic analyses of 73 near-full-length genomes, 16 “lineages” (a term that is used hereafter for discussion purposes and does not imply taxonomic standing) were identified within HIV-1C. The lineages were supported by high bootstrap values in maximum-parsimony and neighbor-joining analyses and were confirmed by the maximum-likelihood method. The nucleotide diversity between the 73 HIV-1C isolates (mean value of 8.93%; range, 2.9 to 11.7%) was significantly higher than the diversity of the samples to the consensus sequence (mean value of 4.86%; range, 3.3 to 7.2%, P < 0.0001). The translated amino acid distances to the consensus sequence were significantly lower than distances between samples within all HIV-1C proteins. The consensus sequences of HIV-1C proteins accompanied by amino acid frequencies were presented (that of Gag is presented in this work; those of Pol, Vif, Vpr, Tat, Rev, Vpu, Env, and Nef are presented elsewhere [http://www.aids.harvard.edu/lab_research/concensus_sequence.htm ]). Additionally, in the promoter region three NF-κB sites (GGGRNNYYCC) were identified within the consensus sequences of the entire set or any subset of HIV-1C isolates. This study suggests that the consensus sequence approach could overcome the high genetic diversity of HIV-1C and facilitate an AIDS vaccine design, particularly if the assumption that an HIV-1C antigen with a more extensive match to the circulating viruses is likely to be more efficacious is proven in efficacy trials.

Initial Response to Highly Active Antiretroviral Therapy in Hiv-1c-infected Adults in a Public Sector Treatment Program in Botswana

Objective:To describe the response to highly active antiretroviral treatment (HAART) in a public sector pilot antiretroviral (ARV) treatment program in Botswana. Methods:The response to HAART is described in adult HIV-infected ARV-naive patients initiating treatment from April 2001 to January 2002 at Princess Marina Hospital in Gaborone, Botswana. Patients had medical and laboratory evaluations before initiating ARV treatment and were followed longitudinally. For analysis, data were collected from charts and patient management records. Results:One hundred fifty-three ARV-naive patients initiated HAART. Most received didanosine plus stavudine (ddI + d4T) with efavirenz or nevirapine. The mean CD4+ cell count increase was 149 cells/mm3 at 24 weeks and 204 cells/mm3 at 48 weeks. The percentage of patients with an HIV-1 RNA level ≤400 copies/mL was 87.0% at 24 weeks and 78.8% at 48 weeks. The Kaplan-Meier 1-year survival estimate was 84.7% (79.0%, 90.8%), with a 3.2-fold increased risk (P = 0.004) of mortality among patients with a CD4+ cell count <50 cells/mm3. The 1-year Kaplan-Meier estimate of toxicity-related drug switches was 32.2% (20.3%, 40.4%). The most common toxicity was peripheral neuropathy, occurring more frequently in patients with a preexisting diagnosis of peripheral neuropathy and among those placed on ddI + d4T-containing regimens. Conclusions:An excellent response to HAART was observed among HIV-1C-infected patients, paralleling those seen elsewhere. Despite excellent responses, high rates of toxicity were observed for ddI + d4T-containing regimens.

Magnitude and Frequency of Cytotoxic T-Lymphocyte Responses: Identification of Immunodominant Regions of Human Immunodeficiency Virus Type 1 Subtype C

ABSTRACT A systematic analysis of immune responses on a population level is critical for a human immunodeficiency virus type 1 (HIV-1) vaccine design. Our studies in Botswana on (i) molecular analysis of the HIV-1 subtype C (HIV-1C) epidemic, (ii) frequencies of major histocompatibility complex class I HLA types, and (iii) cytotoxic T-lymphocyte (CTL) responses in the course of natural infection allowed us to address HIV-1C-specific immune responses on a population level. We analyzed the magnitude and frequency of the gamma interferon ELISPOT-based CTL responses and translated them into normalized cumulative CTL responses. The introduction of population-based cumulative CTL responses reflected both (i) essentials of the predominant virus circulating locally in Botswana and (ii) specificities of the genetic background of the Botswana population, and it allowed the identification of immunodominant regions across the entire HIV-1C. The most robust and vigorous immune responses were found within the HIV-1C proteins Gag p24, Vpr, Tat, and Nef. In addition, moderately strong responses were scattered across Gag p24, Pol reverse transcriptase and integrase, Vif, Tat, Env gp120 and gp41, and Nef. Assuming that at least some of the immune responses are protective, these identified immunodominant regions could be utilized in designing an HIV vaccine candidate for the population of southern Africa. Targeting multiple immunodominant regions should improve the overall vaccine immunogenicity in the local population and minimize viral escape from immune recognition. Furthermore, the analysis of HIV-1C-specific immune responses on a population level represents a comprehensive systematic approach in HIV vaccine design and should be considered for other HIV-1 subtypes and/or different geographic areas.

Identification of Human Immunodeficiency Virus Type 1 Subtype C Gag-, Tat-, Rev-, and Nef-Specific Elispot-Based Cytotoxic T-Lymphocyte Responses for AIDS Vaccine Design

ABSTRACT The most severe human immunodeficiency virus type 1 (HIV-1) epidemic is occurring in southern Africa. It is caused by HIV-1 subtype C (HIV-1C). In this study we present the identification and analysis of cumulative cytotoxic T-lymphocyte (CTL) responses in the southern African country of Botswana. CTLs were shown to be an important component of the immune response to control HIV-1 infection. The definition of optimal and dominant epitopes across the HIV-1C genome that are targeted by CTL is critical for vaccine design. The characteristics of the predominant virus that causes the HIV-1 epidemic in a certain geographic area and also the genetic background of the population, through the distribution of common HLA class I alleles, might impact dominant CTL responses in the vaccinee and in the general population. The enzyme-linked immunospot (Elispot) gamma interferon assay has recently been shown to be a reliable tool to map optimal CTL epitopes, correlating well with other methods, such as intracellular staining, tetramer staining, and the classical chromium release assay. Using Elispot with overlapping synthetic peptides across Gag, Tat, Rev, and Nef, we analyzed HIV-1C-specific CTL responses of HIV-1-infected blood donors. Profiles of cumulative Elispot-based CTL responses combined with diversity and sequence consensus data provide an additional characterization of immunodominant regions across the HIV-1C genome. Results of the study suggest that the construction of a poly-epitope subtype-specific HIV-1 vaccine that includes multiple copies of immunodominant CTL epitopes across the viral genome, derived from predominant HIV-1 viruses, might be a logical approach to the design of a vaccine against AIDS.

Effects of HIV-related stigma among an early sample of patients receiving antiretroviral therapy in Botswana

Abstract Botswana, with its estimated HIV prevalence of 37%, instituted a policy of universal access to antiretroviral therapy (ART) in 2002. Initial enrolment lagged behind expectations, with a shortfall in voluntary testing that observers have attributed to HIV-related stigma – although there are no published data on stigma among HIV-positive individuals in Botswana. We interviewed 112 patients receiving ART in 2000, finding evidence of pervasive stigma in patterns of disclosure, social sequelae, and delays in HIV testing. Ninety-four percent of patients reported keeping their HIV status secret from their community, while 69% withheld this information even from their family. Twenty-seven percent of patients said that they feared loss of employment as a result of their HIV status. Forty percent of patients reported that they delayed getting tested for HIV; of these, 51% cited fear of a positive test result as the primary reason for delay in seeking treatment, which was often due to HIV-related stigma. These findings suggest that success of large-scale national ART programmes will require initiatives targeting stigma and its social, economic and political correlates.

Lessons from the second Aids virus, Hiv-2

Although the clinical signs and symptoms of human immunodeficiency virus (HIV)-2 are similar to those associated with HIV-1 infection, the former virus has a markedly lower perinatal transmission rate and heterosexual infectivity potential. An ongoing cohort study in Senegal, where the disease was first encountered a decade ago, of 136 HIV-2-infected women found an overall incidence of acquired immunodeficiency syndrome of only 0.18/100 person-years in 548 person-years of observation. Moreover, the rate of developing an abnormal CD4 lymphocyte count from the time of infection onward was 1%/year for HIV-2 infected women compared to 10% for HIV-1. In vitro studies of HIV-2 have shown reduced cell killing, less syncytia formation, and slower viral replication compared to HIV-1. It remains unclear whether viral features alone account for the long clinical latency period and different transmission dynamics of HIV-2. An interesting early finding of the Senegalese study is that partial protection from HIV-1 exists in those already infected with HIV-2. Further delineation of the mechanisms involved in this seeming protective effect should be a high research priority given the potential for prevention of the more virulent HIV-1 strain.