Resistencia transmitida de VIH-1 en pacientes sin exposición a tratamiento antirretroviral: Guatemala / Transmitted HIV-1 resistance in patients without exposure to antiretroviral treatment: Guatemala / Resistência transmitida ao HIV-1 em pacientes sem exposição ao tratamento antirretroviral: Guatemala

El objetivo del estudio fue describir los niveles de resistencia transmitida de VIH-1 en adultos atendidos en Unidades de Atención Integral de Guatemala. El estudio incluyó registros de 185 pacientes adultos VIH-1 positivo, de reciente diagnóstico sin antecedente de uso de TAR, de noviembre del 2019 a noviembre del 2020. El análisis se realizó en el software DeepChek® v2.0, para la clasificación de la resistencia se siguió el algoritmo de Stanford HIVdb (v9.4 - 07/12/2022). Se encontró 18.4% (IC 95% 13.1 - 24.7%) de resistencia general a alguna familia de ARVs. Se evidenció 15.1% (IC 95% 10.3 - 21.1%) de resistencia individual a la familia de INNTR afectando principalmente a NVP y EFV; 2.2% (IC 95% 0.6 - 5.4%) de resistencia a INTR, mayormente a FTC/3TC; y 2.7% (IC 95% 0.9 - 6.2%) de resistencia intermedia y baja los IP NFV y LPV/r. Tres casos presentaron resistencia múltiple a los INTR + INNTR. Las mutaciones más frecuentemente encontradas fueron K103N (41.2%), M184V/I (8.8%) y M46I (5.9%). La elevada resistencia transmitida del VIH-1 en pacientes atendidos en distintas Unidades de Atención Integral del VIH, demuestra la importancia de analizar periódicamente la tendencia de la resistencia en personas que no han estado expuestas a ARVs, lo cual a su vez es un marcador indirecto de presencia de resistencia adquirida en el país, datos que evidencian la necesidad de acciones e intervenciones prontas y efectivas dado su impacto en la salud pública.

The objective of this study was to describe the levels of transmitted HIV-1 resistance in patients with a recent HIV diagnosis before starting ART, treated in Comprehensive Care Units in Guatemala during the years 2019 and 2020. The study included records of 185 HIV-positive adult patients, recently diagnosed with HIV without a history of ART use. The analysis was carried out in the DeepChek® v2.0 software, the Stanford HIVdb algorithm (v9.4 - 07/12/2022) was followed to classify resistance. 18.4% (95% CI 13.1 - 24.7%) of general resistance to some family of ARVs was found. There was evidence of 15.1% (95% CI 10.3 - 21.1%) of individual resistance to the NNRTI family, mainly affecting NVP and EFV; 2.2% (95% CI 0.6 - 5.4%) resistance to INTR, mostly to FTC/3TC; and 2.7% (95% CI 0.9 - 6.2%) of intermediate and low resistance IP NFV and LPV/r. Three cases presented multiple resistance to NRTIs + NNRTIs. The most frequently found mutations were K103N (41.2%), M184V/I (8.8%) and M46I (5.9%). The high transmitted resistance of HIV-1 in patients treated in different Comprehensive HIV Care Units demonstrates the importance of periodically analyzing the trend of resistance in people who have not been exposed to ARVs, which in turn is an indirect marker. of the presence of acquired resistance in the country, data that demonstrate the need for prompt and effective actions and interventions given its impact on public health.

O objetivo deste estudo foi descrever os níveis de resistência transmitida ao HIV-1 em adultos tratados em Unidades de Cuidados Integrais na Guatemala. O estudo incluiu prontuários de 185 pacientes adultos HIV-1 positivos, recentemente diagnosticados sem histórico de uso de TARV, no período de novembro de 2019 a novembro de 2020. A análise foi realizada no software DeepChek® v2.0, para classificação da resistência, O algoritmo Stanford HIVdb (v9.4 - 07/12/2022) foi seguido. Foi encontrada 18.4% (IC 95% 13.1 - 24.7%) de resistência geral a alguma família de ARVs. Houve evidência de 15.1% (IC 95% 10.3 - 21.1%) de resistência individual à família de NNRTI, afetando principalmente NVP e EFV; 2.2% (IC 95% 0.6 - 5.4%) resistência ao INTR, principalmente ao FTC/3TC; e 2.7% (IC 95% 0.9 - 6.2%) de resistência intermediária e baixa ao IP NFV e LPV/r. Três casos apresentaram resistência múltipla a NRTIs + NNRTIs. As mutações mais frequentemente encontradas foram K103N (41.2%), M184V/I (8.8%) e M46I (5.9%). A elevada resistência transmitida do HIV-1 em pacientes atendidos em diferentes Unidades de Cuidados Integrados ao HIV demonstra a importância de analisar periodicamente a tendência de resistência em pessoas que não foram expostas aos ARVs, o que por sua vez é um marcador indireto da presença de ARVs adquiridos. resistência no país, dados que demonstram a necessidade de ações e intervenções rápidas e eficazes dado o seu impacto na saúde pública.

Antiretroviral drugs saquinavir and ritonavir reduce inhibitory concentration values of itraconazole against Histoplasma capsulatum strains in vitro

Abstract Recent studies have shown that some drugs that are not routinely used to treat fungal infections have antifungal activity, such as protease inhibitor antiretroviral drugs. This study investigated the in vitro susceptibility of Histoplasma capsulatum var. capsulatum to saquinavir and ritonavir, and its combination with the antifungal itraconazole. The susceptibility assay was performed according to Clinical and Laboratory Standards Institute guidelines. All strains were inhibited by the protease inhibitor antiretroviral drugs. Saquinavir showed minimum inhibitory concentrations ranging from 0.125 to 1 μg mL−1 for both phases, and ritonavir presented minimum inhibitory concentrations ranging from 0.0312 to 4 μg mL−1and from 0.0625 to 1 μg mL−1 for filamentous and yeast phase, respectively. Concerning the antifungal itraconazole, the minimum inhibitory concentration values ranged from 0.0019 to 0.125 μg mL−1 and from 0.0039 to 0.0312 μg mL−1 for the filamentous and yeast phase, respectively. The combination of saquinavir or ritonavir with itraconazole was synergistic against H. capsulatum, with a significant reduction in the minimum inhibitory concentrations of both drugs against the strains (p < 0.05). These data show an important in vitro synergy between protease inhibitors and itraconazole against the fungus H. capsulatum.

Seroconversión frente a primovacunación reforzada contra hepatitis B en niños con cáncer / Seroconversion in response to a reinforced primary hepatitis B vaccination in children with cancer

Introducción: La respuesta inmune a los antígenos de las vacunas está disminuida en los niños con cáncer. El objetivo de este estudio fue evaluar la seroconversión frente a vacuna ADN recombinante contra hepatitis B al momento del inicio de la quimioterapia y/o remisión en niños con cáncer. Pacientes y método: Estudio prospectivo, bicéntrico, controlado, no aleatorizado de niños con diagnóstico reciente de cáncer pareados con niños sanos. Los casos fueron vacunados a tiempo 0, 1 y 6 meses, a dosis de 20 y 40 μg si eran < ó > 10 años, respectivamente, con vacuna ADN recombinante contra hepatitis B, en el momento del diagnóstico en el caso de los tumores sólidos y luego de la remisión en el caso de los tumores hematológicos. El grupo control recibió el mismo esquema, con dosis de 10 o 20 μg respectivamente. Se midieron anticuerpos séricos anti-HBs a los 2, 8 y 12 meses posvacunación. Seroconversión se definió como títulos anti-HBs > 10 mUI/ml al octavo mes. Resultados: Un total de 78 niños con cáncer y 25 controles fueron evaluados con títulos anti-HBs al octavo mes. La tasa de seroconversión fue de 26,9%, en niños con cáncer, sin diferencia por edad, género ni tipo de tumor (p = 0,13; 0,29; y 0,44, respectivamente), y de 100% en el grupo control (p < 0,0001, comparado con los niños con cáncer). En el seguimiento a los 12 meses solo el 31,9% de los niños con cáncer presentaba títulos anti-HBs > 10 mUI/ml. Conclusiones: La vacunación contra hepatitis B con vacuna ADN recombinante, con esquema reforzado de 3 dosis, en el momento del inicio de la quimioterapia y/o remisión provee una respuesta inmune insuficiente en la mayoría de los niños con cáncer. En esta población debieran evaluarse vacunas de tercera generación, con adyuvantes más inmunogénicos, esquemas reforzados a los 0, 1, 2 y 6 meses, medición de títulos de anticuerpos al octavo y duodécimo mes, eventual uso de refuerzos y reevaluación de inmunogenicidad si correspondiese.

Introduction: Immune response against vaccine antigens may be impaired in children with cancer. The aim of this study was to evaluate the seroconversion response against hepatitis B vaccination (HBV) at the time of chemotherapy onset and/or remission in children with cancer. Patients and method: Prospective, two-centre, controlled, non-randomised study conducted on children recently diagnosed with cancer, paired with healthy subjects. Cases received HBV at time 0, 1 and 6 months with DNA recombinant HBV at a dose of 20 and 40 μg if < or > than 10 years of age, respectively, at the time of diagnosis for solids tumours and after the remission in case of haematological tumours. Controls received the same schedule, but at of 10 and 20 μg doses, respectively. HBs antibodies were measured in serum samples obtained at 2, 8 and 12 months post-vaccination. Protective titres were defined as > 10 mIU/ml at 8th month of follow up. Results: A total of 78 children with cancer and 25 healthy controls were analysed at month 8th of follow up. Seroconversion rates in the cancer group reached 26.9%, with no differences by age, gender or type of tumour (P = .13, .29, and .44, respectively). Control group seroconversion was 100% at the 8th month, with P < .0001 compared with the cancer group. At month 12 of follow up, just 31.9% of children with cancer achieved anti-HBs antibodies > 10 mIU/ml. Conclusions: Vaccination against hepatitis B with three doses of DNA recombinant vaccine at an increased concentration, administrated at the time of onset of chemotherapy and/or remission provided an insufficient immune response in a majority of children with cancer. More immunogenic vaccines should be evaluated in this special population, such as a third generation, with more immunogenic adjuvants, enhanced schedules at 0, 1, 2, 6 month, evaluation of antibody titres at month 8 and 12 h to evaluate the need for further booster doses.

¿Es posible que se genere resistencia al dolutegravir cuando se utiliza este agente en el tratamiento de primera línea? / Is resistance to Dolutegravirpossible when this drug is used in first-line therapy?

Dolutegravir (DTG) es un inhibidor de la integrasa del VIH aprobado recientemente como tratamiento por la FDA (Food and Drug Administration) en los Estados Unidos. Utilizado como parte de un tratamiento de primera línea, DTG es el único tratamiento antirretroviral frente al cual no se ha seleccionado resistencia en la clínica. Nuestra teoría es que esto se debe al prolongado tiempo de unión del DTG a la enzima integrasa así como a una capacidad de replicación muy disminuida por parte de los virus que podrían volverse resistentes al DTG. Además, conjeturamos que DTG podría ser utilizado en estrategias que apunten a la erradicación del VIH...

Dolutegravir (DTG) is an HIV integrase inhibitor that was recently approved for therapy by the Food and Drug Administration in the United States. When used as part of First-line therapy, DTG is the only HIV drug that has not selected for resistance mutations in the clinic. We believe that this is due to the long binding time of DTG to the integrase enzyme as well as greatly diminished replication capacity on the parte of viruses that might become resistant to DTG. We further speculatethat DTG might be able to be used in strategies aimed at HIV eradication...

In vivo assessment of antiretroviral therapy-associated side effects

Antiretroviral therapy has been associated with side effects, either from the drug itself or in conjunction with the effects of human immunodeficiency virus infection. Here, we evaluated the side effects of the protease inhibitor (PI) indinavir in hamsters consuming a normal or high-fat diet. Indinavir treatment increased the hamster death rate and resulted in an increase in triglyceride, cholesterol and glucose serum levels and a reduction in anti-oxLDL auto-antibodies. The treatment led to histopathological alterations of the kidney and the heart. These results suggest that hamsters are an interesting model for the study of the side effects of antiretroviral drugs, such as PIs.

Antiretroviral activity of protease inhibitors against Toxoplasma gondii / Terapia antiretroviral de inibidores da protease contra Toxoplasma gondii

The introduction of highly active antiretroviral therapy (HAART) has caused a marked reduction in the occurrence and severity of parasitic infections, including the toxoplasmic encephalitis (TE). These changes have been attributed to the restoration of cell-mediated immunity. This study was developed to examine the activity of six antiretroviral protease inhibitors (API) on Toxoplasma gondii tachyzoites. The six API showed anti-Toxoplasma activity, with IC50 value between 1.4 and 6.6 µg/mL. Further studies at the molecular level should be performed to clarify if the use of API could be beneficial or not for AIDS patients with TE.

La introducción de la terapia antirretroviral de alta efectividad ha causada una marcada reducción en la ocurrencia y curso clínico de las infecciones parasitarias, incluyendo la toxoplasmosis encefálica (TE). Estos cambios han sido atribuidos a la restauración celular. Este estudio fue desarrollado para examinar la actividad de seis inhibidores de proteasas antirretrovirales (IPA) sobre taquizoitos de Toxoplasma gondii. Los seis IPA mostraron actividad anti-Toxoplasma, con valores de CI50 entre 1.4 y 6.6 µg/mL. Futuros estudios a nivel molecular deben ser realizados, los cuales podrán delucidar si el uso de IPA pudiera beneficiar o no a los pacientes que sufren de TE.

Prevalence and patterns of HIV transmitted drug resistance in Guatemala / Prevalencia y patrones de farmacorresistencia transmitida del VIH en Guatemala

Objective. To assess human immunodeficiency virus (HIV) diversity and the prevalence of transmitted drug resistance (TDR) in Guatemala. Methods. One hundred forty-five antiretroviral treatment-naïve patients referred to the Roosevelt Hospital in Guatemala City were enrolled from October 2010 to March 2011. Plasma HIV pol sequences were obtained and TDR was assessed with the Stanford algorithm and the World Health Organization (WHO) TDR surveillance mutation list. Results. HIV subtype B was highly prevalent in Guatemala (96.6%, 140/145), and a 2.8% (4/145) prevalence of BF1 recombinants and 0.7% (1/145) prevalence of subtype C viruses were found. TDR prevalence for the study period was 8.3% (12/145) with the Stanford database algorithm (score > 15) and the WHO TDR surveillance mutation list. Most TDR cases were associated with non-nucleoside reverse transcriptase inhibitors (NNRTIs) (83.3%, 10/12); a low prevalence of nucleoside reverse transcriptase inhibitors and protease inhibitors was observed in the cohort (< 1% for both families). Low selection of antiretroviral drug resistance mutations was found, except for NNRTI-associated mutations. Major NNRTI mutations such as K101E, K103N, and E138K showed higher frequencies than expected in ART-naïve populations. Higher literacy was associated with a greater risk of TDR (odds ratio 4.14, P = 0.0264). Conclusions. This study represents one of the first efforts to describe HIV diversity and TDR prevalence and trends in Guatemala. TDR prevalence in Guatemala was at the intermediate level. Most TDR cases were associated with NNRTIs. Further and continuous TDR surveillance is necessary to gain more in-depth knowledge about TDR spread and trends in Guatemala and to optimize treatment outcomes in the country.

Objetivo. Evaluar la diversidad del virus de la inmunodeficiencia humana (VIH) y la prevalencia de la farmacorresistencia transmitida en Guatemala. Métodos. Entre octubre del 2010 y marzo del 2011 se incluyeron en el estudio 145 pacientes no tratados anteriormente con antirretrovirales, derivados al Hospital Roosevelt en la Ciudad de Guatemala. Se obtuvieron las secuencias pol a partir del VIH plasmático y se evaluó la farmacorresistencia transmitida con el algoritmo de Stanford y la lista de mutaciones para la vigilancia de la farmacorresistencia transmitida de la Organización Mundial de la Salud (OMS). Resultados. El subtipo B del VIH fue sumamente prevalente en Guatemala (96,6%, 140/145), y se encontró una prevalencia de formas recombinantes BF1 de 2,8% (4/145) y una prevalencia del subtipo C del virus de 0,7% (1/145). La prevalencia de la farmacorresistencia transmitida durante el período de estudio fue de 8,3% (12/145) según el algoritmo de la base de datos de Stanford (puntuación > 15) y la lista de mutaciones para la vigilancia de la farmacorresistencia transmitida de la OMS. En la mayoría de los casos, la farmacorresistencia transmitida se asoció con los inhibidores de la transcriptasa inversa no análogos de nucleósidos (ITINN) (83,3%, 10/12); en la cohorte se observó una baja prevalencia asociada con los inhibidores de la transcriptasa inversa análogos de nucleósidos y con los inhibidores de la proteasa (< 1% para ambas familias de fármacos). Se encontró una baja selección de mutaciones causantes de farmacorresistencia debidas a los antirretrovirales, excepto en las mutaciones asociadas a los ITINN. Las mutaciones importantes relacionadas con los ITINN, como K101E, K103N y E138K, mostraron frecuencias más elevadas que las esperadas en las poblaciones vírgenes de tratamiento antirretroviral. En las personas con un nivel de escolaridad más elevado se encontró un mayor riesgo de farmacorresistencia transmitida (razón de posibilidades 4,14; P = 0,0264). Conclusiones. Este estudio representa uno de los primeros intentos de describir la diversidad del VIH, y la prevalencia de la farmacorresistencia transmitida y sus tendencias en Guatemala. La prevalencia de la farmacorresistencia transmitida en Guatemala presentó un nivel intermedio y en la mayoría de los casos se asoció con los ITINN. Se necesita una vigilancia más intensa y sostenida de la farmacorresistencia transmitida para conocer más exhaustivamente su grado de diseminación y sus tendencias en Guatemala, al igual que para optimizar los resultados del tratamiento antirretroviral en el país.

HIV transmitted drug resistance in adult and pediatric populations in Panama / Farmacorresistencia transmitida del VIH en poblaciones adultas y pediátricas en Panamá

Objetivo. Investigar la prevalencia de farmacorresistencia transmitida del VIH en adultos en Panamá mediante un estudio del umbral modificado de la Organización Mundial de la Salud (OMS) e investigar las tasas de resistencia inicial en lactantesseropositivos para el VIH en Panamá.Métodos. En el Instituto Conmemorativo Gorgas, en 47 adultos seropositivos al VIH se efectuó la genotipificación de las mutaciones asociadas con la farmacorresistencia transmitida en los genes de la transcriptasa inversa y la proteasa del VIH-1, según las directrices del estudio umbral de la OMS, modificadas para incluir a las personas ≤ 26 años de edad. Las tasas de prevalencia de las mutaciones farmacorresistentes contra tres clases de fármacos antirretroviral —inhibidores de la transcriptasa inversaanálogos de nucleósidos, inhibidores de la transcriptasa inversa no análogos de nucleósidos e inhibidores de la proteasa— se clasificaron en bajas (< 5,0%), moderadas (5,0%–15,0%) o altas (> 15,0%). También se llevó a cabo genotipificación y se calcularonlas tasas de prevalencia de las mutaciones causantes de farmacorresistencia en 25 lactantes.Resultados. En los adultos de Panamá la farmacorresistencia transmitida fue moderada: 6 de 47 adultos seropositivos para el VIH presentaron una o más mutacionesasociadas con farmacorresistencia transmitida. Las mutaciones farmacorresitentes de transmisión horizontal fueron moderadas para los inhibidores de la transcriptasainversa análogos de nucleósidos y los inhibidores de la transcriptasa inversa no análogos de nucleósidos, y bajas para los inhibidores de la proteasa. En Panamá la transmisiónvertical del VIH ha disminuido en el período 2002–2007, pero la prevalenciade la farmacorresistencia del VIH transmitida por vía vertical es moderada (12,0%) y está surgiendo como un problema debido a la cobertura antirretroviral incompletadurante el embarazo...

Objective. To investigate the prevalence of transmitted drug-resistant HIV among adults in Panama by using a modified World Health Organization Threshold Survey (WHO-TS) and to investigate rates of initial resistance among HIV-positive infants in Panama.Methods. At the Gorgas Memorial Institute, 47 HIV-positive adults were genotyped for mutations associated with transmitted drug resistance (TDR) in the reverse transcriptase andprotease genes of HIV-1, according to WHO-TS guidelines, modified to include patients ≤ 26 years old. Prevalence rates for drug-resistance mutations against three classes of antiretroviraldrugs—nucleoside analog reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors—were calculated as low (< 5.0%), moderate (5.0%–15.0%), and high (> 15.0%). Twenty-five infant patients were also genotyped and prevalence rates for drug-resistance mutations were calculated. Results. TDR among Panamanian adults was moderate: 6 of 47 HIV-positive adultsshowed one or more mutations associated with TDR. Horizontal TDR mutations were moderate for NRTIs and NNRTIs and low for protease inhibitors. Vertical transmission of HIV inPanama has decreased for 2002–2007, but vertical HIV TDR prevalence is moderate (12.0%) and is emerging as a problem due to incomplete antiretroviral coverage in pregnancy. Conclusions. The prevalence of HIV TDR indicated by this study, combined with knownrates of HIV infection in Panama, suggests more extensive surveys are needed to identify risk factors associated with transmission of HIV drug resistance. Specific WHO-TS guidelines for monitoring vertical transmission of drug-resistant HIV should be established.

Analysis of resistance testing in South Trinidad / Análisis de prueba de resistencia en Trinidad Sur

The introduction of antiretroviral therapy in Trinidad and Tobago in the 1980s has resulted in a decrease in mortality of HIV-infected persons. Poor adherence to antiretroviral therapy (ART) has resulted in the development of multidrug resistant HIV. Resistance testing done on 40 samples showed that 64.8% of patients had K103 mutation, 75.6% of patients had M184 mutations and 62% of patients showed resistance to tenofovir suggesting that the K65R mutation was highly likely to be present. There was reduced activity to the protease inhibitors; no resistance was found to the protease inhibitor, darunavir. Thus, there is a need for salvage therapy to be introduced which will result in virologic suppression and potentially stop the spread of multidrug resistant HIV. Darunavir, a new generation protease inhibitor, is an essential part of salvage therapy and needs to be introduced into the national formulary.

La introducción de la terapia antiretroviral en Trinidad y Tobago en la década de 1980, ha producido una disminución en la mortalidad de personas infectadas por el VIH. La adhesión pobre a la terapia antiretroviral (TAR) ha conducido al desarrollo de una variedad de VIH resistente a las multidrogas. Las pruebas de resistencia realizadas a 40 muestras mostró que el 64.8% de los pacientes tenían mutación K103, 75.6% de los pacientes tenían mutaciones M184, y 62% de pacientes mostraron resistencia al tenofovir, lo que indica una alta probabilidad de mutación K65R. Había actividad reducida respecto a los inhibidores de la proteasa; mientras que no se halló ninguna resistencia en el inhibidor de la protease, darunavir. Así, hay necesidad de introducir una terapia de salvamento qué produzca una supresión virológica y potencialmente detenga la diseminación del VIH resistente a las multidrogas. El darunavir - inhibidor de nueva generación frente a la proteasa -es una parte fundamental de la terapia de salvamento y necesita ser introducido en el formulario nacional.

Oral candidiasis in HIV+ patients under treatment with protease inhibitors

The purpose of this work was to evaluate the influence of Protease Inhibitors (PI) on the occurrence of oral candidiasis in 111 HIV+ patients under PI therapy (Group A). The controls consisted of 56 patients that were not using PI drugs (Group B) and 26 patients that were not using any drugs for HIV therapy (Group C). The patient's cd4 cell counts were taken in account for the correlations. One hundred and ninety three patients were evaluated. The PI did not affect the prevalence of oral candidiasis (p = 0.158) or the frequency of C. albicans isolates (p = 0.133). Patients with lower cd4 cell counts showed a higher frequency of C. albicans isolates (p = 0.046) and a greater occurrence of oral candidiasis (p = 0.036).

Obstacles to successful antiretroviral treatment of HIV-1 infection: problems & perspectives.

Mutations in human immunodeficiency virus type 1 (HIV-1) are a major impediment to successful highly active antiretroviral therapy (HAART) and the design of anti-HIV vaccines. Although HAART has made long-term suppression of HIV a reality, drug resistance, drug toxicity, drug penetration, adherence to therapy, low levels of continued viral replication in cellular reservoirs and augmentation of host immune responses are some of the most important challenges that remain to be sorted out. Continuing viral replication in the face of HAART leads to the accumulation of drug resistance mutations, increase in viral loads and eventual disease progression. Patients who fail therapy have minimal options for their clinical management. Therefore, a clear understanding of the pathogenesis of drug-resistant HIV-1, and all of the issues that influence the success of HAART is urgently needed. In the present article, we discuss various obstacles to HIV therapy, and provide perspectives relating to these issues that are critical in determining the success or failure of HAART.