Transmission of drug-resistant strains of HIV-1: unfortunate, but inevitable

Demonstration of sustained drug-resistant human immunodeficiency virus type 1 lineages circulating among treatment-naïve individuals

Transmission of human immunodeficiency virus (HIV) drug resistance is well-recognized and compromises response to first-line therapy. However, the population dynamics of transmitted resistance remains unclear, although previous models have assumed that such transmission reflects direct infection from treated individuals. We investigated whether population-based phylogenetic analyses would uncover lineages of resistant viruses circulating in untreated individuals. Through the phylogenetic analysis of 14,061 HIV type 1 (HIV-1) pol gene sequences generated in the United Kingdom from both treatment-naïve and -experienced individuals, we identified five treatment-independent viral clusters containing mutations conferring cross-resistance to antiretroviral drugs prescribed today in the United Kingdom. These viral lineages represent sustainable reservoirs of resistance among new HIV infections, independent of treatment. Dated phylogenies reconstructed through Bayesian Markov chain Monte Carlo inference indicated that these reservoirs originated between 1997 and 2003 and have persisted in the HIV-infected population for up to 8 years. Since our cohort does not represent all infected individuals within the United Kingdom, our results are likely to underestimate the number and size of the resistant reservoirs circulating among drug-naïve patients. The existence of sustained reservoirs of resistance in the absence of treatment has the capacity to threaten the long-term efficacy of antiretroviral therapy and suggests there is a limit to the decline of transmitted drug resistance. Given the current decrease in resistance transmitted from treated individuals, a greater proportion of resistance is likely to come from drug-naïve lineages. These findings provide new insights for the planning and management of treatment programs in resource-rich and developing countries.

Preliminary findings of an intervention integrating modified directly observed therapy and risk reduction counseling

Various interventions have been proposed to address these ongoing needs of HIV-positive patients as they encounter challenges with medication adherence and risk reduction. This report presents the findings of a study that pilots 'DAART+', an intervention that integrates modified directly observed therapy (MDOT), and risk reduction counseling for a population of marginally housed, substance-using persons. The pilot study intended to assess the feasibility of the intervention and to obtain data to assess the intervention's potential effectiveness. The preliminary data reveal that 83% of participants who completed the intervention (n=18) had undetectable viral load (VL) (VL< or =400 copies/mL) which represents a 2.15 log(10) decrease from baseline. Risk behaviors also changed modestly with self-reported increases in condom usage.

The epidemiological impact of antiretroviral use predicted by mathematical models: a review

This review summarises theoretical studies attempting to assess the population impact of antiretroviral therapy (ART) use on mortality and HIV incidence. We describe the key parameters that determine the impact of therapy, and argue that mathematical models of disease transmission are the natural framework within which to explore the interaction between antiviral use and the dynamics of an HIV epidemic. Our review focuses on the potential effects of ART in resource-poor settings. We discuss choice of model type and structure, the potential for risk behaviour change following widespread introduction of ART, the importance of the stage of HIV infection at which treatment is initiated, and the potential for spread of drug resistance. These issues are illustrated with results from models of HIV transmission. We demonstrate that HIV transmission models predicting the impact of ART use should incorporate a realistic progression through stages of HIV infection in order to capture the effect of the timing of treatment initiation on disease spread. The realism of existing models falls short of properly reproducing patterns of diagnosis timing, incorporating heterogeneity in sexual behaviour, and describing the evolution and transmission of drug resistance. The uncertainty surrounding certain effects of ART, such as changes in sexual behaviour and transmission of ART-resistant HIV strains, demands exploration of best and worst case scenarios in modelling, but this must be complemented by surveillance and behavioural surveys to quantify such effects in settings where ART is implemented.

Human immunodeficiency virus reservoir might be actively eradicated as residual malignant cells by cytotoxic chemotherapy

A unique characteristic of human immunodeficiency virus (HIV) infection is that the virus must incorporate its cDNA into the host genomic DNA for replication. Once the virus gets into the host genome and becomes a part of the host genetic materials, elimination of the virus without killing the infected cells is virtually impossible. The use of highly active antiretroviral therapy (HAART) can result in a substantial decline in viremia. However, HAART does not eradicate HIV. The progressive HIV infection will unavoidably rebound after a cessation of the treatment. Searching for a new combination therapeutic strategy with cytotoxic agents that eliminate or significantly reduce the HIV reservoir is a potential way for better control of the disease. Theoretically, the HIV reservoir can be gradually eradicated by long-term use of certain antimetabolic cytotoxic drugs coupled with proper activation of latently infected cells, if viral replication is completely blocked by antiretroviral chemotherapy to protect uninfected, susceptible cells.

Transmission of HIV-1 drug resistance

BACKGROUND

The use of highly-active anti-retroviral therapy (HAART) for treating HIV infections is increasing. Recent studies have demonstrated that HAART is improving both the length and quality of life in HIV-infected patients. Resistant strains of HIV arise when drug adherence is poor. This can lead to the transmission of drug-resistant strains of HIV to susceptible individuals. This can lead to suboptimal first-line therapy, if the resistance profile of the transmitted virus is unknown.

OBJECTIVES

To review the mechanisms of how drug resistance arises; the methods used to characterise drug resistance; the problems arising with compliance leading to the development of drug-resistant HIV strains; the evidence for the incidence, prevalence and trends in the transmission of resistant HIV strains in different risk groups; and the evidence of suboptimal response to first-line therapy where transmission of a resistant HIV strain has occurred. On the basis of this, a case is presented for the routine resistance testing of all newly diagnosed HIV-infected individuals.

STUDY DESIGN

Literature review.

RESULTS AND CONCLUSIONS

There is evidence, though limited at present, that transmission of drug-resistant HIV strains can lead to suboptimal response to first-line therapy in newly diagnosed HIV-infected individuals. As the use of HAART can only increase in the future, and compliance will always be a problem in such HAART-treated patients, baseline resistance testing should become a routine part of their management.

Epidemiological aspects of transmitted HIV drug resistance

Transmitted human immunodeficiency virus (HIV) resistance to antiretrovirals (i.e. resistance in antiretroviral naive patients) emerged during the 1990s as a potentially relevant public health problem. HIV variants resistant to all classes of approved antiretroviral agents have been identified in significant proportions antiretroviral naive patients, and this phenomenon appears as a potential threat to the effectiveness of highly active antiretroviral therapy. Available data from surveys conducted between 1996 and 2001 show the prevalence of drug resistance among newly HIV-infected individuals to range from 3%, to above 20% in North America, and from 5% to 15% in Europe. Increases in prevalence observed during the late 1990s in some studies are not confirmed by most recent data. Transmission of multidrug resistance still appears to be an uncommon occurrence. However, methodological heterogeneity and problems in study design make it difficult to compare results between different surveys and to draw firm conclusions from the results. There is a clear need to improve surveillance systems aimed at identifying patients at the time of primary infection and to standardize laboratory methods for the identification of genetic markers of resistance to be used for epidemiological purposes.

Predicting death from HIV/AIDS: a case-control study from Florida public HIV/AIDS clinics

BACKGROUND

After markedly decreasing for 3 years, HIV/AIDS mortality declined only slightly in 1999.

METHODS

The authors conducted a case-control study in four Florida urban public health HIV clinics to evaluate modifiable factors associated with HIV/AIDS mortality in a non-research setting. Structured chart review was conducted for 120 case-patients who died in 1999 and for 240 randomly selected control-patients. Risk factors associated with death in univariate analysis were entered into three conceptually related, matched logistic regression models.

RESULTS

In the final multivariate model, homelessness (adjusted odds ratio [AOR], 9.98; 95% confidence interval [CI], 2.34-42.5), Medicaid insurance (AOR, 3.10; 95% CI, 1.43-6.74), having a documented adherence problem (AOR, 3.50; 95% CI, 1.64-7.47), injection drug use (AOR, 2.46; 95% CI, 1.11-5.43), non-specific liver failure (AOR, 76.9; 95% CI, 6.79-870.9), interrupted highly active antiretroviral therapy (HAART) secondary to side effects (AOR, 4.00; 95% CI, 1.46-10.9), and not receiving HAART (AOR, 2.62; 95% CI, 1.03-6.68) were independent predictors of mortality.

CONCLUSIONS

In addition to medical and clinical indicators, several sociobehavioral-demographic factors remained important throughout the multivariate analysis. Improvement in care should include a focus on social circumstances of infected people. Special attention to the homeless, those with adherence problems, and those with liver disease is clearly indicated.

Rapid and sensitive oligonucleotide ligation assay for detection of mutations in human immunodeficiency virus type 1 associated with high-level resistance to protease inhibitors

A sensitive, specific, and high-throughput oligonucleotide ligation assay (OLA) for the detection of genotypic human immunodeficiency virus type 1 (HIV-1) resistance to Food and Drug Administration-approved protease inhibitors was developed and evaluated. This ligation-based assay uses differentially modified oligonucleotides specific for wild-type or mutant sequences, allowing sensitive and simple detection of both genotypes in a single well of a microtiter plate. Oligonucleotides were designed to detect primary mutations associated with high-level resistance to amprenavir, nelfinavir, indinavir, ritonavir, saquinavir, and lopinavir, including amino acid substitutions D30N, I50V, V82A/S/T, I84V, N88D, and L90M. Plasma HIV-1 RNA from 54 infected patients was amplified by reverse transcription-PCR and sequenced by using dideoxynucleotide chain terminators for evaluation of mutations associated with drug resistance. These same amplicons were genotyped by the OLA at positions 30, 50, 82, 88, 84, and 90 for a total of 312 codons. The sensitivity of detection of drug-resistant genotypes was 96.7% (87 of 90 mutant codons) in the OLA compared to 92.2% (83 of 90) in consensus sequencing, presumably due to the increased sensitivity of the OLA. The OLA detected genetic subpopulations more often than sequencing, detecting 30 mixtures of mutant and wild-type sequences and two mixtures of drug-resistant sequences compared to 15 detected by DNA sequencing. Reproducible and semiquantitative detection of the mutant and the wild-type genomes by the OLA was observed by analysis of wild-type and mutant plasmid mixtures containing as little as 5% of either genotype in a background of the opposite genome. This rapid, simple, economical, and highly sensitive assay provides a practical alternative to dideoxy sequencing for genotypic evaluation of HIV-1 resistance to antiretrovirals.

AIDS policy modeling for the 21st century: an overview of key issues

Decisions about HIV prevention and treatment programs are based on factors such as program costs and health benefits, social and ethical issues, and political considerations. AIDS policy models--that is, models that evaluate the monetary and non-monetary consequences of decisions about HIV/AIDS interventions--can play a role in helping policy makers make better decisions. This paper provides an overview of the key issues related to developing useful AIDS policy models. We highlight issues of importance for researchers in the field of AIDS policy modeling as well as for policy makers. These include geographic area, setting, target groups, interventions, affordability and effectiveness of interventions, type and time horizon of policy model, and type of economic analysis. This paper is not intended to be an exhaustive review of the AIDS policy modeling literature, although many papers from the literature are discussed as examples; rather, we aim to convey the composition, achievements, and challenges of AIDS policy modeling.

A new paradigm for HIV care: ethical and clinical considerations

Although dramatic advances in clinical treatment have greatly improved the lives of many people with HIV/AIDS, many other patients do not have information about or access to these treatments because of health care providers' presumptive judgments about patients' ability to adhere to medical regimens. The authors contend that with sufficient support and education most patients, even those with difficult social and medical problems, can be helped to initiate and maintain HIV treatment in accordance with current clinical standards. This commentary delineates a new paradigm for HIV care in which patients and providers collaborate on individualized plans to establish patients' readiness for treatment, ensure maintenance of treatment, and make use of the social services necessary to accomplish these goals. Providers have an ethical responsibility to do everything possible to see that patients who might benefit from new HIV treatments have a fair opportunity to do so, and health systems have a responsibility to facilitate this process. Substantial progress toward meeting these responsibilities can be made within the current health care environment.