Recent origin of human immunodeficiency virus type 1 variants in resting CD4+ T lymphocytes in untreated and suboptimally treated subjects.
(9/2958)
Resting CD4(+) T lymphocytes are an important reservoir for human immunodeficiency virus type 1 (HIV-1) in treated patients with undetectable viremia. The knowledge of viral persistence in these cells is limited, however, for patients without treatment or patients for whom treatment is failing; therefore, this reservoir in such patients was characterized. Virus variants were characterized in 3 subjects who were followed-up from primary HIV-1 infection and 5 treatment-experienced subjects. No founder viral sequences and only a minority of the earlier identified drug-induced mutations were found in the resting T lymphocytes. Instead, the viral sequences were closely related to those detected simultaneously in plasma, except in 2 treatment-experienced subjects. Thus, a turnover and replenishment of this virus reservoir in peripheral blood is likely to occur in most persons with detectable viremia. However, infrequently the virus variants in plasma and resting T cells seem to be derived from independent sources. (+info)
Evaluation of viral resistance to reverse transcriptase inhibitors (RTI) in HIV-1-infected patients before and after 6 months of single or double antiretroviral therapy.
(10/2958)
We evaluated samples of peripheral blood mononuclear (PBMC) cells from 46 AIDS patients, before starting therapy with HIV-1 reverse transcriptase inhibitors (RTI), and after 6 months of drug use. PBMC were stored and tested by a Line Probe Assay (LiPA), in order to assess the frequency of RT mutations in this population. Six patients were taking AZT before initial blood collection (1 to 16 weeks of drug use) and 40 patients had no prior therapy. After baseline evaluation, 19 patients received AZT, 23 AZT plus DDI, 3 started AZT only with DDI added after 3 months, and 3 received a combination of AZT plus 3TC. Detection of at least one mutation was found in 33% (15/46) of patients at baseline, and 83% (38/46) had at least 1 mutation after 6 months of therapy. In the majority of cases, samples presented with the wild type and variants of HIV, simultaneously. Patients receiving monotherapy had a higher frequency of mutations (L41 and F214, Y215) than did patients receiving double-drug therapy (19 vs. 10). No specific mutation associated with DDI was identified in 26 patients so treated. Despite the finding of a mean increase in CD4 count and a mild decrease in viral load, patients tended to have an inverse correlation between the CD4 variation and number of mutations detected after 6 months, suggesting potential loss of drug efficacy in the presence of these genotypic changes. (+info)
Novel non-nucleoside inhibitors of cytomegaloviruses (BAY 38-4766): in vitro and in vivo antiviral activity and mechanism of action.
(11/2958)
For two decades it has been impossible to develop drugs with novel mechanisms of action against herpesviruses, and treatment has been confined largely to the use of inhibitors of viral DNA polymerase. As a representative of a novel inhibitory approach, the non-nucleosidic BAY 38-4766 was identified as a highly selective inhibitor of human cytomegalovirus (HCMV). The compound selectively inhibits not only HCMV strains, including ganciclovir-resistant, ganciclovir/foscarnet and ganciclovir/cidofovir double-resistant clinical isolates, but also a number of monkey and rodent cytomegaloviruses. In a murine cytomegalovirus (MCMV) pathogenicity model in mice, antiviral efficacy and excellent tolerability were demonstrated. BAY 38-4766-resistant HCMV and MCMV strains are not cross-resistant to the nucleoside analogues ganciclovir and cidofovir or the pyrophosphate analogue foscarnet, indicating a different mode of action. Mechanistic studies demonstrated that the high selectivity of this drug class is most likely due to the inhibition of a late stage of the viral replication cycle. Sequence analyses of resistant HCMV and MCMV strains revealed mutations in UL89 and UL104, proteins known to be involved in viral DNA cleavage and packaging. Consequently, the drug is highly specific for the viral as opposed to cellular functions, since UL89 is related to a bacteriophage terminase and no human equivalent exists. In addition, because some of the genes of the viral DNA cleavage and packaging complex are highly conserved among herpesviruses, development of broad-spectrum agents covering additional human herpesviruses might be possible using this approach. (+info)
Analysis of HIV-1 drug resistant mutations by line probe assay and direct sequencing in a cohort of therapy naive HIV-1 infected Italian patients.
(12/2958)
BACKGROUND: The routine determination of drug resistance in newly HIV-1 infected individuals documents a potential increase in the transmission of drug-resistant variants. Plasma samples from twenty seven therapy naive HIV-1 infected Italian patients were analyzed by the line probe assay (LIPA) and the TruGene HIV-1 assay for the detection of mutations conferring resistance to HIV-1. RESULTS: Both tests disclosed amino-acid substitutions associated with resistance in a variable number of patients. In particular, two mutations (K70R and V118I), detectable by LIPA and by sequencing analysis respectively, revealed resistance to NRTIs in two plasma samples. At least three mutations conferring resistance to NNRTIs, not detectable by commercial LIPA, able to reveal mutations associated only with nucleoside reverse transcriptase analogues, were disclosed by viral sequence analysis. Moreover, most samples showed mutations correlated with resistance to protease inhibitors. Remarkably, a key mutation, like V82A (found as a mixture), and some "indeterminate" results (9 samples), due the absence of signal on the lines corresponding to a specific probe, was revealed only by LIPA, while a variable number of secondary mutations was detectable only by TruGene HIV-1 assay. CONCLUSION: Even if further studies are necessary to establish the impact of different tests on the evaluation of drug-resistant strains transmission, LIPA might be useful in a wide population analysis, where bulk results are needed in a short time, while sequencing analysis, able to detect mutations conferring resistance to both NRTIs and NNRTIs, might be considered a more complete assay, albeit more expensive and more technically complex. (+info)
Rate of emergence of cytomegalovirus (CMV) mutations in leukocytes of patients with acquired immunodeficiency syndrome who are receiving valganciclovir as induction and maintenance therapy for CMV retinitis.
(13/2958)
The emergence of mutations conferring ganciclovir resistance was evaluated in an open-label randomized clinical trial that compared oral valganciclovir with intravenous ganciclovir as induction therapy, followed by maintenance with valganciclovir, for newly diagnosed cytomegalovirus (CMV) retinitis in 148 patients with acquired immunodeficiency syndrome. The presence of CMV mutations was directly assessed in patient leukocytes by polymerase chain reaction, followed by restriction fragment-length polymorphism (RFLP) for detection of the most common UL97 mutations associated with ganciclovir resistance and by sequencing of the viral UL97 gene. The cumulative percentages of patients with UL97-mutant viruses at 3, 6, 12, and 18 months (based on the number of patients on treatment at each time point) was 2.2%, 6.5%, 12.8%, and 15.3%, respectively. Of the 20 relevant UL97 mutations found by sequencing in 14 patients, 14 (70%) were detected by RFLP analysis. The rate of emergence of ganciclovir-resistant viruses with use of oral valganciclovir is no greater than that reported with use of intravenous ganciclovir. (+info)
Postexposure prophylaxis for human immunodeficiency virus infection after sexual or injection drug use exposure: identification and characterization of the source of exposure.
(14/2958)
In a nonrandomized study of nonoccupational postexposure prophylaxis (PEP), a cross-sectional evaluation of subjects who were the source of human immunodeficiency (HIV) exposure was performed to characterize partners of index subjects seeking nonoccupational PEP against HIV. Among 401 index subjects, 64 (16%) recruited a source subject. Those in a steady relationship and those who knew that the source subject was HIV antibody positive were more likely to recruit their source subject. Source subjects reported high rates of past (78%) and current (69%) antiretroviral use; 46% of those using antiretroviral drugs had detectable plasma HIV-1 RNA levels. Antiretroviral resistance was detected in many source subjects who reported any use of antiretrovirals and was rare among source subjects who reported no history of antiretroviral use. Clinicians often make treatment decisions on the basis of incomplete knowledge of the source subject's HIV status or antiretroviral treatment history. The treatment history, particularly nonuse of a class of antiretroviral drugs, can be used to predict drug resistance. (+info)
Soluble tumour necrosis factor alpha receptor 2, a serum marker of resistance to the anabolic actions of growth hormone in subjects with HIV disease.
(15/2958)
Therapies are still being sought for the prevention of loss of body weight and lean body mass in HIV disease. The purpose of the present study was to identify a serum marker that would help in selecting patients who may be appropriate candidates for the use of anabolic agents, such as growth hormone, to restore lean body mass. This study included 26 HIV-infected patients and nine healthy controls, assessed previously for the effectiveness of 2 weeks of growth hormone administration in the stimulation of protein synthesis in skeletal muscle. Serum levels of interleukins-1beta, -6 and -10 were not useful predictors of the anabolic response to growth hormone. Serum concentrations of tumour necrosis factor alpha (TNFalpha) were significantly elevated (P<0.05) in patients with AIDS and AIDS-related weight loss, and there was a significant correlation between the serum concentration of interleukin-1 receptor antagonist and stage of disease (P=0.03). However, the serum concentration of the soluble TNFalpha receptor type 2 was most predictive of an inability of muscle protein synthesis to respond anabolically to growth hormone (r=-0.42, P=0.01). These data suggest that inflammation impacts on the responsiveness of muscle tissue to an anabolic stimulus, and that the soluble TNFalpha receptor type 2 provides a useful serum marker for metabolic dysfunction in HIV disease, which can be used to identify individuals likely to respond to growth hormone-based anabolic therapy. (+info)
Absence of rapid selection for acyclovir or penciclovir resistance following suboptimal oral prodrug therapy of HSV-infected mice.
(16/2958)
BACKGROUND: Acyclovir (ACV) resistant herpes simplex virus (HSV) isolates can be readily selected in animal infection models receiving suboptimal ACV treatment, however no comparative studies of the emergence of resistance following suboptimal treatment with valacyclovir (VCV) or famciclovir (FCV), the prodrugs of acyclovir and penciclovir, respectively, have been reported. METHODS: Mice (n = 30) were infected with HSV type 1 or 2 in the ear pinnae and administered oral prodrugs at one fifth a dose previously shown to be effective. To select and amplify drug-resistant HSV, a total of seven consecutive in vivo passages with suboptimal treatment were performed for each virus sample and progeny virus from each passage was characterized by the plaque reduction (PRA) and plating efficiency assays (PEA). RESULTS: No drug-resistant HSV-2 and only a single drug-resistant HSV-1 variant were identified. Virus recovered from the first three sequential passages of this HSV-1 sample was susceptible by PRA, although the proportion of resistant virus recovered gradually increased upon passage. The resistant HSV-1 phenotype was confirmed by PRA after four sequential passages in mice. Unexpectedly, this in vivo-selected drug-resistant HSV-1 failed to yield an infection completely refractory to treatment in subsequent passages. CONCLUSIONS: Sub-optimal therapy of immunocompetent mice with either VCV or FCV did not readily select for HSV-mutants resistant to either ACV or PCV, suggesting that selection of resistance with either prodrug remains difficult using this system. Futhermore, this study suggests that the PEA may represent a useful adjunct to the PRA for monitoring alterations in the proportion of drug-resistant virus even when no change in IC50 is apparent. (+info)