Progressive multifocal leukoencephalopathy in a patient post allo-HCT successfully treated with JC virus specific donor lymphocytes.

BACKGROUND: Progressive multifocal leukoencephalopathy is a demyelinating CNS disorder. Reactivation of John Cunningham virus leads to oligodendrocyte infection with lysis and consequent axonal loss due to demyelination. Patients usually present with confusion and seizures. Late diagnosis and lack of adequate therapy options persistently result in permanent impairment of brain functions. Due to profound T cell depletion, impairment of T-cell function and potent immunosuppressive factors, allogeneic hematopoietic cell transplantation recipients are at high risk for JCV reactivation. To date, PML is almost universally fatal when occurring after allo-HCT. METHODS: To optimize therapy specificity, we enriched JCV specific T-cells out of the donor T-cell repertoire from the HLA-identical, anti-JCV-antibody positive family stem cell donor by unstimulated peripheral apheresis [1]. For this, we selected T cells responsive to five JCV peptide libraries via the Cytokine Capture System technology. It enables the enrichment of JCV specific T cells via identification of stimulus-induced interferon gamma secretion. RESULTS: Despite low frequencies of responsive T cells, we succeeded in generating a product containing 20 000 JCV reactive T cells ready for patient infusion. The adoptive cell transfer was performed without complication. Consequently, the clinical course stabilized and the patient slowly went into remission of PML with JCV negative CSF and containment of PML lesion expansion. CONCLUSION: We report for the first time feasibility of generating T cells with possible anti-JCV activity from a seropositive family donor, a variation of virus specific T-cell therapies suitable for the post allo transplant setting. We also present the unusual case for successful treatment of PML after allo-HCT via virus specific T-cell therapy.

The phosphoprotein genes of measles viruses from subacute sclerosing panencephalitis cases encode functional as well as non-functional proteins and display reduced editing.

Products expressed from the second (P/V/C) gene are important in replication and abrogating innate immune responses during acute measles virus (MV) infection. Thirteen clone sets were derived from the P/V/C genes of measles virus (MV) RNA extracted from brains of a unique collection of seven cases of subacute sclerosing panencephalitis (SSPE) caused by persistent MV in the central nervous system (CNS). Whether these functions are fully maintained when MV replicates in the CNS has not been previously determined. Co-transcriptional editing of the P mRNAs by non-template insertion of guanine (G) nucleotides, which generates mRNAs encoding the viral V protein, occurs much less frequently (9%) in the SSPE derived samples than during the acute infection (30-50%). Thus it is likely that less V protein, which is involved in combatting the innate immune response, is produced. The P genes in MV from SSPE cases were not altered by biased hypermutation but exhibited a high degree of variation within each case. Most but not all SSPE derived phospho-(P) proteins were functional in mini genome replication/transcription assays. An eight amino acid truncation of the carboxyl-terminus made the P protein non-functional while the insertion of an additional glycine residue by insertion of G nucleotides at the editing site had no effect on protein function.

Prevalence of hepatitis B virus infection among health care workers in a tertiary hospital in Tanzania.

BACKGROUND: Sub-Saharan Africa has a high prevalence of hepatitis B virus (HBV) infections. Health care workers (HCWs) are at high risk of contracting HBV infection through their occupation. Vaccination of HCWs against HBV is standard practice in many countries, but is often not implemented in resource-poor settings. We aimed with this cross-sectional study to determine HBV prevalence, HCW vaccination status, and the risk factors for HCWs contracting HBV infection in Tanzania. METHODS: We enrolled 600 HCWs from a tertiary Tanzanian hospital. Their demographics, medical histories, HBV vaccination details and risk factors for contracting blood-borne infections were collected using a standardized questionnaire. Serum samples were tested for HBV and hepatitis C virus (HCV) markers by ELISA techniques, PCR and an anti-HBs rapid test. HCWs were divided in two subgroups: those at risk of contracting HBV (rHCW 79.2%) via exposure to potentially infectious materials, and those considered not at risk of contracting HBV (nrHCW, 20.8%). RESULTS: The overall prevalence of chronic HBV infection (HBsAg+, anti-HBc+, anti-HBs-) was 7.0% (42/598). Chronic HBV infection was found in 7.4% of rHCW versus 5.6% of nrHCW (p-value = 0.484). HCWs susceptible to HBV (HBsAg-, anti-HBc-, anti-HBs-) comprised 31.3%. HBV immunity achieved either by healed HBV infection (HBsAg-, anti-HBc+, anti-HBs+) or by vaccination (HBsAg-, anti-HBc-, anti-HBs+) comprised 36.5% and 20.2%, respectively. 4.8% of participants had indeterminate results (HBsAg-, anti-HBc+, anti-HBc-IgM-, anti-HBs-). Only 77.1% of HCWs who received a full vaccination course had an anti-HBs titer >10 ml/U. An anti-HBs point-of-care test was 80.7% sensitive and 96.9% specific. There was a significantly higher risk for contracting HBV (anti-HBc+) among those HCW at occupational risk (rHCW) of older age (odds ratios (OR) in rHCW 3.297, p < 0.0001 vs. nrHCW 1.385, p = 0.606) and among those HCW being employed more than 11 years (OR 2.51, p < 0.0001***). HCV prevalence was low (HCV antibodies 1.2% and HCV-RNA 0.3%). CONCLUSIONS: Chronic HBV infection is common among Tanzanian HCWs. One third of HCWs were susceptible to HBV infection, highlighting the need for vaccination. Due to high prevalence of naturally acquired immunity against HBV pre-testing might be a useful tool to identify susceptible individuals.

Low trough levels of tipranavir in a combination antiretroviral therapy of tipranavir/ritonavir and tenofovir require therapeutic drug monitoring.

The new non-peptidic protease inhibitor tipranavir is used boosted with ritonavir in a 500/200 mg bid scheme. Multiple drug interactions are described for both drugs because of their different action in CYP450 3A4 and p-glycoprotein. In this retrospective analysis of 22 patients during therapy with tipranavir/ritonavir (TPV) 500 mg/200 mg bid, we found significantly decreased TPV-trough levels in combination with tenofovir (15.32+/-5.22 microg/ml) in comparison to TPV trough levels without tenofovir (20.21+/-14.87 microg/ml). Therapeutic drug monitoring of TPV is recommended.

Therapy of interferon-induced depression in chronic hepatitis C with citalopram: a randomised, double-blind, placebo-controlled study.

BACKGROUND: Interferon-induced depression represents a major complication in antiviral treatment of chronic hepatitis C virus (HCV) infection. AIM: To evaluate in a placebo-controlled study the efficacy of a selective serotonin reuptake inhibitor (SSRI) in HCV patients on antiviral therapy with interferon-associated depression. METHODS: 100 HCV outpatients were included in a randomised, double-blind, placebo-controlled study. During interferon therapy (peginterferon alpha-2b plus ribavirin), depression was monitored using the Hospital Anxiety and Depression Scale (HADS). Patients with clinically relevant interferon-induced depression (HADS >or=9) were randomly assigned to placebo or citalopram (SSRI, 20 mg/day). RESULTS: In 28 patients (28%), HADS scores increased to >8 during interferon therapy. They were treated with placebo (n = 14) or SSRI (n = 14). HADS scores declined significantly in SSRI patients within four weeks of therapy (p<0.001) but not in placebo patients. This difference between subgroups was statistically significant (p = 0.032). Unblinding became necessary in five placebo patients as a result of intolerable depression. Rescue medication (20 mg citalopram) led to a significant decrease in HADS scores (p = 0.008). All citalopram patients were able to complete interferon therapy as planned. As an interim analysis showed a significant superiority of SSRI over placebo, the study was terminated prematurely. Three patients, who became depressed afterwards, were treated in an unblinded fashion with citalopram. CONCLUSIONS: The findings demonstrate clearly that citalopram treatment is highly effective in HCV patients on interferon therapy, when initiated after the onset of clinically relevant depressive symptoms. This suggests that a general SSRI prophylaxis is not necessary in these patients.

Freeze-thawing of breast milk does not prevent cytomegalovirus transmission to a preterm infant.

Freezing human milk is recommended to inactivate cytomegalovirus (CMV). A case of a preterm infant exclusively receiving frozen breast milk from his CMV seropositive mother showed that storage of breast milk for two months at -20 degrees C did not prevent symptomatic postnatal CMV infection.

Sexual dysfunction in males with chronic hepatitis C and antiviral therapy: interferon-induced functional androgen deficiency or depression?

Decrease of libido and erectile dysfunction are reported by male patients during antiviral therapy of chronic hepatitis C, but therapy-associated underlying factors for sexual dysfunction are not well defined. To assess putative contributions of interferon-induced sex hormone changes to sexual dysfunction, we prospectively investigated changes in free testosterone, total testosterone, dehydroepiandrosterone sulfate, prolactin, sex hormone-binding globulin, FSH and LH levels and psychometric self-assessment scores in 34 male patients treated with interferon alfa-2b (5 MIU three times weekly) (n=19)+ ribavirin (n=15) for 6-12 months. Depression was measured by the Hospital Anxiety and Depression Scale. Sexual dysfunction was evaluated by the Symptom Checklist 90 Item Revised and a five-point rating scale assessing sexual arousal disorder. Free and total testosterone decreased significantly during antiviral therapy in close correlation with libido/sexual function. Depression scores increased during therapy and were also significantly associated with sexual dysfunction. However, androgen levels displayed no significant correlation with depression. These results suggest that interferon-induced decrease in sexual function is associated - but not causally related -with both androgen reduction and increased depressive symptoms. These findings may affect care for male hepatitis C patients during interferon therapy.

Lipid lowering therapy with fluvastatin and pravastatin in patients with HIV infection and antiretroviral therapy: comparison of efficacy and interaction with indinavir.

BACKGROUND: Lipoprotein disorders in HIV-positive patients receiving highly active antiretroviral therapy (HAART) are becoming a major concern in HIV treatment, since there is growing evidence for an association between HAART-induced hyperlipidemia and increased cardiovascular risk. Yet relatively few data are available on the possible interactions of HAART and treatment with statins. PATIENTS AND METHODS: In this prospective study, 25 HIV-positive, treatment-experienced patients (five female, 20 male, all Caucasian) were treated with either fluvastatin or pravastatin. Total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) levels, and serum triglycerides were determined at regular intervals, as well as therapeutic drug monitoring to assess possible drug interactions. RESULTS: In 13 pravastatin-treated patients, a decrease in total cholesterol levels (from 7.12 mmol/l to 6.29 mmol/l) after 12 weeks of therapy was seen. In 12 patients treated with fluvastatin, a permanent reduction of total cholesterol (from 6.46 mmol/l to 5.31 mmol/l) after 12 weeks was observed. The reduction of LDL levels was 30.2% in the fluvastatin group and 14.4% in the pravastatin group. In eight patients receiving an indinavir-containing HAART, indinavir plasma levels were not significantly influenced. No effect on triglycerides or HDL was observed. CONCLUSION: Fluvastatin and pravastatin are efficient in lowering total and LDL cholesterol levels in HIV-positive patients receiving HAART. Furthermore, no influence on indinavir plasma levels could be observed. Therefore, both compounds seem to be a viable treatment option in HAART-induced hypercholesterolemia.

Frequent detection of Mycoplasma pneumoniae in Bell's palsy.

The cause of Bell's palsy (BP) remains unknown despite various hints to an infectious etiology. Mycoplasma pneumoniae is a common pathogen of the respiratory tract causing pharyngitis, tracheobronchitis or pneumonia. Neurological complications are the most frequent extrapulmonary manifestation. So far, only a few case reports suggested an association between cranial nerve palsy and M. pneumoniae infection. Patients with a BP who were admitted to the Department of Otorhinolaryngology or Neurology of the University of Wuerzburg between 2000 and 2002 were tested serologically for the presence of antibodies against Borrelia burgdorferi, herpes viruses (HSV-1/2, VZV) and M. pneumoniae. The diagnosis of mycoplasmal infection was made when at least one of the following criteria was met: a threefold rise or more in the titer of antibody of M. pneumoniae in paired sample or a microparticle agglutination assay (MAG) of > or =1:40 and the detection of IgA and/or IgM antibodies in the acute phase serum. Ninety-one consecutive patients could be included. Fifteen patients showed a reactivation of a VZV ( n=12) or of a HSV-1 ( n=3) infection. In six cases the immunoblot revealed specific antibody bands for B. burgdorferi. In 24 patients (26.4%) a seroconversion of M. pneumoniae could be detected. Only two patients complained of mild respiratory symptoms. According to our results, M. pneumoniae is frequently associated with Bell's palsy. Thus, a routine screening for this pathogen, even in the absence of respiratory symptoms, is necessary.

Subacute sclerosing panencephalitis in two brothers.

We report the occurrence of subacute sclerosing panencephalitis (SSPE) in two brothers two years after measles infection. The diagnosis was confirmed by compatible data from medical history, occurrence of autochthonic measles virus (MV) IgG production in the central nervous system (CNS), and pathognomonic EEG changes. Pathogenetically, SSPE is caused by a genome mutation of intracellularly persisting MV, causing viral nucleocapsides to accumulate in the brain cells. A specific predisposing immune defect is not known. The occurrence of two cases in one family is suggestive of a genetic predisposing factor.

Cellular and humoral immune reconstitution after autologous peripheral blood stem cell transplantation (PBSCT).

Immune reconstitution after autologous peripheral blood stem cell transplantation (PBSCT) is of particular interest because of its importance for clinical outcome. Despite prolonged immunosuppression, especially of CD4(+) cells, few infections after neutrophil recovery occur. Only reactivation of varicella zoster virus (VZV) is more frequent in the first year after transplantation. From August 1997 to May 2001, we prospectively evaluated 38 patients prior to conditioning and during follow-up of 12 months post-transplant for virus antibodies [measles, mumps, rubella, polio, herpes simplex, varicella zoster, mononucleosis, cytomegalovirus (CMV)] and lymphocyte subpopulations by flow cytometry. CD3(+) T lymphocytes, CD8(+) T cells, and B-lymphocyte reconstitution in our study confirms previous reports. Complete CD4(+) lymphocyte reconstitution was not achieved in the 12 months post-transplant leading to a suppressed CD4/CD8 ratio. IgG antibody titers against measles, mumps, rubella, and polio were present in almost all patients pretransplant and during 12 months post-transplant, indicating persistent humoral immunity. CD3(+) and CD8(+) counts of patients with clinical VZV reactivation ( n=5) post-transplant were significantly higher (median: 1201/microl and 938/microl, respectively) than in patients without VZV reactivation (median: 594/microl and 482/microl, respectively) 6-12 months post-transplant. Positive CMV titers pretransplant ( n=19) were also correlated with higher CD3(+) and CD8(+) counts 3-6 months post-transplant (median: 1050/microl and 1056/microl, respectively) compared to CMV-negative patients (738/microl and 584/microl, respectively), although none of the patients suffered from CMV disease. Therefore, we conclude that persistent viral infections can contribute to the CD8(+) T-cell reconstitution after PBSCT by oligoclonal expansion of antigen-specific memory CD8(+) T cells.

No influence of the P-glycoprotein genotype (MDR1 C3435T) on plasma levels of lopinavir and efavirenz during antiretroviral treatment.

BACKGROUND: In a retrospective study of HIV patients under antiretroviral therapy, we investigated the influence of the MDR1 genotype (C3435T) on plasma levels of lopinavir (LPV) and efavirenz (EFV). METHODS: The MDR1 genotype was analysed from 67 patients who were treated with LPV (n = 32; mean treatment period 53 weeks) and/or EFV (n = 43, mean treatment period 105 weeks) between 1999 and 2003. Plasma levels of LPV (trough levels) and EFV (12-h-levels) were determined every three months. Data were analysed by the Kruskal-Wallis test. RESULTS: There were no significant differences in the LPV and EFV plasma levels with respect to the MDR1 3435 genotype. CONCLUSIONS: We did not find evidence for an influence of the MDR1 3435 genotype on plasma levels of LPV and EFV.

[Intrathecal synthesis pattern of immunoglobulins in meningoencephalitis epidemic due to echovirus 9]. / Patrones de síntesis intratecal de inmunoglobulinas en epidemia de meningoencefalitis por echovirus 9.

INTRODUCTION: Epidemics of meningoencephalitis due to echovirus 9 were commonly occurred when a children population become susceptible for the first time in front the virus. OBJECTIVE: To present the intrathecal synthesis pattern of immunoglobulins of the epidemic that affected Cuba in 1999 and to probe the usefulness of reibergram and antibody index in the diagnostic and characterization of the outbreak. PATIENTS AND METHODS: 23 pediatric patients suffering from viral meningoencephalitis due to echovirus 9 were studied in the income moment. Serum and cerebrospinal fluid IgA, IgM, IgG, albumin and glucose were quantified. Cerebrospinal fluid total protein content and lactate were quantified. Titles of antibodies against echo 9 and Coxsackie A9 and differential cell count were performed. RESULTS: A mean of 555 cells/10 6 L mainly lymphocytes were obtained. Glucose in cerebrospinal fluid was over 50%, serum glucose and lactate levels below 2.1 mmol/L. In the reibergram an absence of intrathecal synthesis was predominant (15/23), IgM synthesis (6/23) and IgM+IgA (2/23). Blood cerebrospinal fluid dysfunction was observed in 15 patients. The mean antibody index was 1,8 for echo 9 and 0,9 for Coxsackie A9. CONCLUSIONS: The intrathecal synthesis pattern of immunoglobulins was different from other enterovirus and from echovirus 9 in non epidemic situations before this epidemic, probably with alteration of viral genome.

Patrones de síntesis intratecal de inmunoglobulinas en epidemia de meningoencefalitis por echovirus 9 / Intrathecal synthesis pattern of immunoglobulins in meningoencephalitis epidemic due to echovirus 9

Introducción. Las epidemias producidas por echovirus 9 son comunes cuando existe una población infantil susceptible que se enfrenta al virus por primera vez. Objetivo. Presentar el patrón de síntesis intratecal (SI) de inmunoglobulinas de la epidemia que afectó a Cuba en 1999 y comprobar la utilidad del reibergrama y del índice de anticuerpo en el diagnóstico y caracterización del brote. Pacientes y métodos. Se estudiaron 23 pacientes con meningoencefalitis vírica por echovirus 9 en el momento del ingreso. Se cuantificaron IgA, IgM, IgG, albúmina, glucosa en suero y líquido cefalorraquídeo (LCR), y proteínas totales y lactato en LCR. Se realizaron los títulos de anticuerpos antiechovirus 9 y Coxsackie A9 y recuento celular diferencial. Resultados. Se obtuvo un recuento celular medio de 555 células/10-6 L con predominio de linfocitos. Los valores de glucosa en LCR estuvieron por encima del 50 por ciento de la glucosa en suero y lactato menor de 2,1 mmol/L. En el reibergrama predominó la ausencia de síntesis (15/23), IgM (6/23) e IgM+IgA (2/23). Hubo disfunción de la barrera sangre-LCR en 15 pacientes. El índice de anticuerpo específico medio fue de 1,8 para echovirus 9 y 0,9 para Coxsackie A9. Conclusión. El patrón de SI de inmunoglobulinas se diferencia del de otros enterovirus y el propio echovirus 9 en situaciones no epidémicas anteriores con probable alteración del genoma vírico (AU)

Efavirenz plasma levels for the prediction of treatment failure in heavily pretreated HIV-1 infected patients.

OBJECTIVE: Efavirenz (EFV) plasma levels have been discussed as a predictor of treatment failure in HIV infected patients. The aim of this prospective, open-labeled, case-control study was to evaluate pretreated patients in regards to efavirenz plasma levels and efficacy of therapy. METHODS: Blood samples were obtained monthly from 33 patients receiving efavirenz in combination with other antiretroviral agents for at least 3 months. EFV plasma concentrations and potease inhibitor (PI) plasma levels were measured by high-performance liquid chromatography (HPLC). EFV plasma levels were correlated with efficacy. In patients with virologic failure genotypic resistance testing was performed. RESULTS: Mean efavirenz plasma levels (n = 240) of 33 patients were 3.119 +/- 2.497 ng/ml. There were no significant differences between median efavirenz plasma levels of 24 patients (72%) with a HIV-RNA < 20 copies/ml (2.168 ng/ml), 3 patients with HIV-RNA of 20 500 copies/ml (3.362 ng/ml), and 6 patients with a virologic failure (>500 copies/ml) (2.190 ng/ml) respectively. Efavirenz plasma levels below 1.000 ng/ml were found in 4/27 effective treated patients, and in 4/6 patients with virologic failure. In all patients with virologic failure multiple NRTI, NNRTI and PI mutations were found in genotypic resistance testing. CONCLUSION: An individual EFV plasma level below 1.000 ng/ml in one single measurement seems to be predictive of viral failure and the developement of genotypic resistance. Therapeutic drug monitoring of EFV might be helpful, especially in heavily pretreated patients, to reach long term sufficently effectiveness of therapy.

Therapeutic drug monitoring of indinavir in HIV-infected patients undergoing HAART.

BACKGROUND: Therapeutic drug monitoring (TDM) of protease inhibitors (PI) is gaining increasing importance for the management of HIV-infected patients undergoing highly active antiretroviral therapy (HAART). The PI indinavir (IDV) is widely used in HAART regimens. Combinations of IDV with ritonavir (RTV) have been used to increase the plasma concentration of IDV. However, the desirable IDV concentration range in clinical practice remains to be elucidated. PATIENTS AND METHODS: To study the value of TDM for IDV in clinical practice, a retrospective analysis of 501 plasma samples of patients treated with IDV in various dosages was performed. IDV levels were determined during routine outpatient visits. Analysis was performed by high pressure liquid chromatography (HPlC) with UV detection. RESULTS: A widespread range of IDV plasma concentrations was seen both within and between patients. The mean IDV level during therapy with IDV 2.4 g/d was 3,260 ng/ml (95% CI: 2,903 ng/ml; 3,618 ng/ml). IDV levels at a dose of IDV 1.6 g/d in combination with RTV resulted in a mean IDV plasma concentration of 4,191 ng/ml (95% CI: 3,356 ng/ml; 5,026 ng/ml). There was no significant difference between plasma levels at the doses of 2.4 g/d and 1.6 g/d. 35 of all 130 patients treated with IDV reached only suboptimal IDV plasma concentrations below the limit of 150 ng/ml. There was no statistically significant difference between the number of patients below an IDV plasma concentration of 150 ng/ml in the various dosage regimens. CONCLUSION: During therapy with IDV in a b.i.d. scheme, similar IDV plasma concentrations and a comparable number of patients with subinhibitory plasma concentrations were observed when compared to a therapeutic regimen with t.i.d. dosing. In this study, even at various times of plasma sampling after oral ingestion, TCM facilitated the surveillance of patients compliance.

Phenotypic analysis of the sensitivity of HIV-1 to inhibitors of the reverse transcriptase, protease, and integrase using a self-inactivating virus vector system.

Conventional phenotypic analysis of resistance of the human immunodeficiency virus (HIV) to antiviral therapy is time-consuming and requires culture of infectious virus. Although phenotypic analyses may be desirable, rapid generation of test results and decentralized availability of the test system will be important to achieve utility in the clinical practice. This study describes the design of an alternative phenotypic resistance test using replication incompetent viral vectors. Chimeric HIV vectors containing a marker gene were generated. The env and most of the regulatory and accessory genes of HIV were removed. In addition, the 3'U3 region was deleted to obtain a self-inactivating construct. Cotransfection of the plasmid with a plasmid that provided the vesicular stomatitis virus glycoprotein resulted in the production of replication-incompetent virus vectors. Infection of susceptible cells with the vectors led to marker gene expression. Vector production in the presence of protease (PR) inhibitors, or infection in the presence of reverse transcriptase (RT) or integrase (IN) inhibitors reduced marker gene expression in a dose-dependent manner. Marker gene activity was preserved at higher drug levels if vectors contained RT and PR genes from resistant virus isolates. Sensitivity to nucleoside and non-nucleoside RT inhibitors, protease and integrase inhibitors could be determined in 10 working days. The phenotypic drug resistance test using replication-incompetent HIV vectors significantly speeds up drug resistance measurements and allows testing at reduced biosafety levels. This will make clinical use of phenotypic assessment of antiviral resistance more feasible.

Characterization of HIV-specific proliferative T cell responses in HIV-infected persons.

Virus-specific helper T cell responses are thought to be an important host defense in HIV infection. The proliferative responses to HIV p24, p55, and gp120 were tested in a cohort of 27 HIV-infected subjects. Vigorous proliferative responses directed at the Gag protein with stimulation indices in excess of 6 were detected in 10 of the individuals tested but an Env-specific response was present in only 1 subject. Viral load and proliferative activity to Gag were inversely correlated in untreated individuals. Proliferation was also observed in some individuals treated in the chronic phase of infection, and responses were maintained over time in the absence of detectable viremia. Positive proliferative responses could also occasionally be detected in treated persons with CD4(+) cell counts below 200/microl. Thus, vigorous Gag-specific proliferative responses are present in a minority of HIV-infected individuals and can be detected in individuals receiving highly active antiretroviral therapy at advanced disease stages. Proliferative responses are maintained for an extended time period in the presence of antiviral therapy.