Temporal trend of drug-resistance and APOBEC editing in PBMC genotypic resistance tests from HIV-1 infected virologically suppressed individuals.

BACKGROUND: We aimed at evaluating the temporal trend of drug-resistance and APOBEC editing from HIV-DNA genotypic resistance tests (GRT) in virologically suppressed individuals. MATERIAL AND METHODS: Major resistance mutations (MRM), genotypic susceptibility score (GSS) for the current regimen and APOBEC-related mutations (APO-M) were evaluated. Potential changes in trends of MRM and APO-M over-time were assessed and predictors of MRM detection or sub-optimal GSS (GSS<2) at HIV-DNA-GRT were estimated through logistic regression analyses. RESULTS: Among the 1126 individuals included, 396 (35.2%) harboured at least one MRM (23.4% to NRTI, 18.8% to NNRTI, 7.7% to PI and 1.4% to INSTI [N=724]); 132 (12.3%) individuals showed a GSS <2. APO-M and stop codons were found in 229 (20.3%) and 105 (9.3%) individuals, respectively. APO-DRMs were found in 16.8% of individuals and were more likely observed in those individuals with stop codons (40.0%) compared to those without (14.4%, P<0.001). From 2010 to 2021 no significant changes of resistance or APO-M were found. Positive predictors of MRM detection at HIV-DNA GRT were drug abuse, subtype B infection, and a prolonged and complex treatment history. Perinatal infection and having at least 2 stop codons were associated with a current suboptimal regimen. CONCLUSIONS: In virologically suppressed individuals, resistance in HIV-DNA and the extent of APOBEC editing were generally stable in the last decade. A careful evaluation of APOBEC editing might be helpful to improve the reliability of HIV-DNA GRT. Further investigations are required to understand how to apply the estimation of APOBEC editing in refining genotypic evaluation.

The novel HBx mutation F30V correlates with hepatocellular carcinoma in vivo, reduces hepatitis B virus replicative efficiency and enhances anti-apoptotic activity of HBx N terminus in vitro.

OBJECTIVE: We aimed to investigate HBx genetic elements correlated with hepatitis B virus (HBV) -related hepatocellular carcinoma (HCC) and their impact on (a) HBV replicative efficiency, (b) HBx binding to circular covalently closed DNA (cccDNA), (c) apoptosis and cell-cycle progression, and (d) HBx structural stability. METHODS: This study included 123 individuals chronically infected with HBV: 27 with HCC (77.9% (21/27) genotype D; 22.1% (6/27) genotype A) and 96 without HCC (75% (72/96) genotype D; 25.0% (24/96) genotype A). HepG2 cells were transfected by wild-type or mutated linear HBV genome to assess pre-genomic RNA (pgRNA) and core-associated HBV-DNA levels, HBx-binding onto cccDNA by chromatin immunoprecipitation-based quantitative assay, and rate of apoptosis and cell-cycle progression by cytofluorimetry. RESULTS: F30V was the only HBx mutation correlated with HCC (18.5% (5/27) in HCC patients versus 1.0% (1/96) in non-HCC patients, p 0.002); a result confirmed by multivariate analysis. In vitro, F30V determined a 40% and 60% reduction in pgRNA and core-associated HBV-DNA compared with wild-type (p <0.05), in parallel with a significant decrease of HBx binding to cccDNA and decreased HBx stability. F30V also decreased the percentage of apoptotic cells compared with wild-type (14.8 ± 6.8% versus 19.1 ± 10.1%, p <0.01, without affecting cell-cycle progression) and increased the probability of HBx-Ser-31 being phosphorylated by PI3K-Akt kinase (known to promote anti-apoptotic activity). CONCLUSIONS: F30V was closely correlated with HBV-induced HCC in vivo, reduced HBV replicative efficiency by affecting HBx-binding to cccDNA and increased anti-apoptotic HBx activity in vitro. This suggests that F30V (although hampering HBV's replicative capacity) may promote hepatocyte survival, so potentially allowing persistent production of viral progeny and initiating HBV-driven hepatocarcinogenesis. Investigation of viral genetic markers associated with HCC is crucial to identify those patients at higher risk of HCC, who hence deserve intensive liver monitoring and/or early anti-HBV therapy.

Recommendations for screening, monitoring, prevention, prophylaxis and therapy of hepatitis B virus reactivation in patients with haematologic malignancies and patients who underwent haematologic stem cell transplantation-a position paper

SCOPE: Hepatitis B virus (HBV) infection reactivation is associated with high morbidity and mortality in patients with haematologic malignancy and/or haematopoietic stem cell transplantation (HSCT). However, information on this issue is limited. The scope of this position paper is to provide recommendations on HBV screening, monitoring, prophylaxis, treatment and vaccination in the patients described above. METHODS: These recommendations were developed from one meeting of experts attended by different Italian scientific societies as well as from a systematic literature review (of articles published through December 31, 2016) on HBV infection in haematologic patients and in patients who underwent haematopoietic stem cell transplantation published in the same issue of the journal. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess each recommendation's quality. QUESTIONS ADDRESSED: These recommendations provide the answers to the following questions: (a) HBV screening and monitoring: Who should be screened before chemotherapy? Which screening tests should be used? Should HBV-DNA detection be used to monitor HBV reactivation before starting antivirals? What is the best timeline to monitor HBV reactivation? (b) Prophylaxis in HBsAg-positive patients: Which antiviral drugs should be used to treat HBsAg-positive patients? How long should antiviral prophylaxis be provided to HBsAg-positive patients? (c) Prophylaxis in patients with resolved HBV infection: Which patients with resolved HBV infection should receive antiviral prophylaxis? Which antiviral drug should be used? How long should antiviral prophylaxis be provided? (d) HBV infection management strategy in autologous (auto-HSCT) and allogeneic HSCT (allo-HSCT): Which HSCT recipients should receive antiviral prophylaxis? Which antiviral drug should be used? How long should antiviral prophylaxis be provided? (e) Choice of antiviral drugs in the treatment of HBV reactivation: Should third-generation anti-HBV drugs be preferred to first- or second-generation antiviral drugs in the treatment of HBV reactivation with or without hepatitis flare in haematologic patients? (f) Immunization against HBV in patients with haematologic malignancies and/or patients who underwent HSCT: Should these patients be vaccinated? Which HBV vaccination schedule should be adopted? RECOMMENDATIONS: Haematologic patients should be screened for hepatitis B surface antigen (HBsAg) plus anti-hepatitis B core protein (HBc), and HBV DNA before chemotherapy. HBV DNA levels should be monitored monthly in all HBV-positive patients who do not receive prophylaxis. HBsAg-positive haematologic patients and those undergoing HSCT should receive third-generation antiviral therapy as prophylaxis. Anti-HBc-positive lymphoma patients and those receiving HSCT should receive antiviral prophylaxis. All HBV-negative haematologic patients should be vaccinated for HBV. The acquisition of data from well-designed studies is desirable in the near future.

Hepatitis B reactivation characterized by HBsAg negativity and anti-HbsAg antibodies persistence in haematopoietic stem cell transplanted patient after lamivudine withdrawal.

BACKGROUND: HBV reactivation is associated with high mortality rates in hematopoietic stem cell transplantation (HSCT) and prophylactic lamivudine (LMV) treatment is suggested to prevent this phenomenon. However, the duration of LMV treatment in HSCT patients is not fully defined and the time of immune recovery is considered the best parameter for a drug to be safely interrupted. In patients undergoing allogeneic HSCT, the time of immune recovery is not easy to define and may take years after transplantation and prolonged LMV treatments, which can lead to drug-resistant viral strains. CASE PRESENTATION: An anti-HBc-positive hematological patient who was undergoing prolonged immunosuppression and who experienced HBV reactivation 3 months after the suspension of a prolonged LMV prophylaxis is described. HBV-DNA matching an atypical serological profile characterized by HbsAg negativity and anti-HBs positivity was detected in the patient. The genotypic analysis of the HBV strain identified T127P, F170FL and S204R mutations of HbsAg, which can hinder HBsAg recognition in a diagnostic assay. CONCLUSIONS: HBV reactivation in the HSCT host can be sustained by HBsAg viral variants with characteristics of altered immunogenicity that cannot be detected by usual laboratory tests. This clinical case description suggests the importance of screening for serum HBV-DNA levels in the diagnosis of HBV reactivation and monitoring HBV-DNA after prophylaxis suspension, particularly in HSCT subjects who have undergone prolonged periods of LMV treatment.

Recommendations for screening, monitoring, prevention, prophylaxis and therapy of hepatitis B virus reactivation in patients with haematologic malignancies and patients who underwent haematologic stem cell transplantation-a position paper.

SCOPE: Hepatitis B virus (HBV) infection reactivation is associated with high morbidity and mortality in patients with haematologic malignancy and/or haematopoietic stem cell transplantation (HSCT). However, information on this issue is limited. The scope of this position paper is to provide recommendations on HBV screening, monitoring, prophylaxis, treatment and vaccination in the patients described above. METHODS: These recommendations were developed from one meeting of experts attended by different Italian scientific societies as well as from a systematic literature review (of articles published through December 31, 2016) on HBV infection in haematologic patients and in patients who underwent haematopoietic stem cell transplantation published in the same issue of the journal. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess each recommendation's quality. QUESTIONS ADDRESSED: These recommendations provide the answers to the following questions: (a) HBV screening and monitoring: Who should be screened before chemotherapy? Which screening tests should be used? Should HBV-DNA detection be used to monitor HBV reactivation before starting antivirals? What is the best timeline to monitor HBV reactivation? (b) Prophylaxis in HBsAg-positive patients: Which antiviral drugs should be used to treat HBsAg-positive patients? How long should antiviral prophylaxis be provided to HBsAg-positive patients? (c) Prophylaxis in patients with resolved HBV infection: Which patients with resolved HBV infection should receive antiviral prophylaxis? Which antiviral drug should be used? How long should antiviral prophylaxis be provided? (d) HBV infection management strategy in autologous (auto-HSCT) and allogeneic HSCT (allo-HSCT): Which HSCT recipients should receive antiviral prophylaxis? Which antiviral drug should be used? How long should antiviral prophylaxis be provided? (e) Choice of antiviral drugs in the treatment of HBV reactivation: Should third-generation anti-HBV drugs be preferred to first- or second-generation antiviral drugs in the treatment of HBV reactivation with or without hepatitis flare in haematologic patients? (f) Immunization against HBV in patients with haematologic malignancies and/or patients who underwent HSCT: Should these patients be vaccinated? Which HBV vaccination schedule should be adopted? RECOMMENDATIONS: Haematologic patients should be screened for hepatitis B surface antigen (HBsAg) plus anti-hepatitis B core protein (HBc), and HBV DNA before chemotherapy. HBV DNA levels should be monitored monthly in all HBV-positive patients who do not receive prophylaxis. HBsAg-positive haematologic patients and those undergoing HSCT should receive third-generation antiviral therapy as prophylaxis. Anti-HBc-positive lymphoma patients and those receiving HSCT should receive antiviral prophylaxis. All HBV-negative haematologic patients should be vaccinated for HBV. The acquisition of data from well-designed studies is desirable in the near future.

Persistent risk of HBV reactivation despite extensive lamivudine prophylaxis in haematopoietic stem cell transplant recipients who are anti-HBc-positive or HBV-negative recipients with an anti-HBc-positive donor.

The overall rate of hepatitis B virus (HBV) reactivation was evaluated in a population of 373 haematological stem cell transplant (HSCT) patients treated with lamivudine (LMV) if they were anti-HBc-positive/HBV-DNA-negative recipients or if they were HBV-negative recipients with an anti-HBc-positive donor. The incidence of HBV reactivation was calculated in two groups of autologous (auto) or allogeneic (allo) HSCT patients who were stratified according to their HBV serostatus. The former group included 57 cases: 10 auto-HSCT and 27 allo-HSCT anti-HBc-positive recipients, two auto-HSCT and three allo-HSCT inactive carriers, and 15 allo-HSCT recipients with an anti-HBc-positive donor. Forty-seven (82.4%) patients in this group received LMV prophylaxis (the median (interquartile range, IQR) of LMV treatment was 30 (20-38) months). The second group consisted of 320 anti-HBc-negative auto-HSCT and allo-HSCT recipients with anti-HBc-negative donors. None of these patients received any prophylaxis. Two patients in the first group and two in the second group experienced reactivation of HBV infection, with an incidence of 3.5% (95% CI 0.4-12.1%) and 0.6% (95% CI 0.1-2.2%), respectively. Only one out of four reactivated patients was LMV-treated. The cumulative probability of HBV reactivation at 6 years from HSCT was 15.8% (95% CI 15.2-16.4%). Three of four viral isolates obtained from the HBV-reactivated patients harboured mutations in the immune-active HBsAg-region. In a HSCT population carefully evaluated for HBV prophylaxis, a risk of HBV reactivation persisted in the group of patients who were not LMV-treated. Only one LMV-treated patient experienced reactivation of HBV with a resistant HBV isolate.

A recent epidemiological cluster of acute hepatitis B genotype F1b infection in a restricted geographical area of Italy.

In this study, by phylogenetic analysis, we identified an epidemiological cluster involving eight individuals diagnosed with acute hepatitis B virus (HBV) infection related to unprotected sexual intercourse in a restricted area of central Italy (time period: 2011-2014). Notably, these patients (six of eight Italians) were infected by subgenotype F1b, which is not commonly found in western countries. Ultra-deep pyrosequencing confirmed a superimposable composition of HBV quasi-species in these patients. Despite the availability of effective vaccination, this study highlights the importance of not underestimating the risk of HBV infection, of continuing to set up surveillance programmes for HBV infection, and of investigating the pathogenetic potential of these atypical genotypes.

Effect of maraviroc on non-R5 tropic HIV-1: refined analysis of subjects from the phase IIb study A4001029.

We characterized maraviroc susceptibility of dual/mixed tropic viruses from subjects enrolled onto phase IIb study A4001029. Maraviroc baseline plasma samples from 13 multidrug-experienced subjects were sequenced and the HIV-1-env gene cloned into pNL4.3Δenv to obtain recombinant viruses. The V3 region was sequenced by the Sanger method and ultradeep sequencing. By analysing subjects having a weighted optimized background therapy susceptibility (wOBT) score of <1, 3/7 subjects were characterized by good in vivo and in vitro response to maraviroc therapy. Molecular docking simulations allowed us to rationalize the maraviroc susceptibility of dual/mixed tropic viruses. A subset of subjects with dual/mixed tropic viruses responded to maraviroc. Further investigations are warranted of CCR5 antagonists in subjects carrying dual/mixed tropic virus that explore the feasible use of maraviroc in subjects that is potentially larger than those infected with a pure R5 virus.

HIV-1 integrase genotyping is reliable and reproducible for routine clinical detection of integrase resistance mutations even in patients with low-level viraemia.

OBJECTIVES: Integrase drug resistance monitoring deserves attention because of the increasing number of patients being treated with integrase strand-transfer inhibitors. Therefore, we evaluated the integrase genotyping success rate at low-level viraemia (LLV, 51-1000 copies/mL) and resistance in raltegravir-failing patients. METHODS: An integrase genotypic resistance test (GRT) was performed on 1734 HIV-1 samples collected during 2006-13. Genotyping success rate was determined according to the following viraemia levels: 51-500, 501-1000, 1001-10 000, 10 001-100 000 and >100 000 copies/mL. The reproducibility of integrase GRT was evaluated in 41 plasma samples processed in duplicate in two reference centres. The relationship between LLV and resistance prevalence was evaluated in a subset of 120 raltegravir-failing patients. RESULTS: Overall, the integrase genotyping success rate was 95.7%. For viraemia levels 51-500 and 501-1000 copies/mL, the rate of success was 82.1% and 94.0%, respectively. GRT was reproducible, producing sequences with a high similarity and an equal resistance profile regardless of the sequencing centre or viraemia level. Resistance was detected both at LLV and at viraemia >1000 copies/mL (51-500 copies/mL = 18.2%; 501-1000 = 37.5%; 1001-10 000 = 53.7%; 10 001-100 000 = 30.0%; and >100 000 = 30.8%). At viraemia ≤500 copies/mL, Q148H/K/R and N155H had the same prevalence (9.1%), while the Y143C/H/R was completely absent. At early genotyping (within 3 months of raltegravir treatment), Q148H/K/R and N155H mutations were detected regardless of the viraemia level, while Y143C/H/R was observed only in samples with viraemia >1000 copies/mL. CONCLUSIONS: Our findings prove the reliability of HIV-1 integrase genotyping and reinforce the concept that this assay may be useful in the management of failures even at LLV.

Genotypic testing on HIV-1 DNA as a tool to assess HIV-1 co-receptor usage in clinical practice: results from the DIVA study group.

PURPOSE: We have developed a sequencing assay for determining the usage of the genotypic HIV-1 co-receptor using peripheral blood mononuclear cell (PBMC) DNA in virologically suppressed HIV-1 infected patients. Our specific aims were to (1) evaluate the efficiency of V3 sequences in B versus non-B subtypes, (2) compare the efficiency of V3 sequences and tropism prediction using whole blood and PBMCs for DNA extraction, (3) compare the efficiency of V3 sequences and tropism prediction using a single versus a triplicate round of amplification. RESULTS: The overall rate of successful V3 sequences ranged from 100 % in samples with >3,000 copies HIV-1 DNA/10(6) PBMCs to 60 % in samples with <100 copies total HIV-1 DNA /10(6) PBMCs. Analysis of 143 paired PBMCs and whole-blood samples showed successful V3 sequences rates of 77.6 % for PBMCs and 83.9 % for whole blood. These rates are in agreement with the tropism prediction obtained using the geno2pheno co-receptor algorithm, namely, 92.1 % with a false-positive rate (FPR) of 10 or 20 % and of 96.5 % with an FPR of 5.75 %. The agreement between tropism prediction values using single versus triplicate amplification was 98.2 % (56/57) of patients using an FPR of 20 % and 92.9 % (53/57) using an FPR of 10 or 5.75 %. For 63.0 % (36/57) of patients, the FPR obtained via the single amplification procedure was superimposable to all three FPRs obtained by triplicate amplification. CONCLUSIONS: Our results show the feasibility and consistency of genotypic testing on HIV-1 DNA tropism, supporting its possible use for selecting patients with suppressed plasma HIV-1 RNA as candidates for CCR5-antagonist treatment. The high agreement between tropism prediction by single and triple amplification does not support the use of triplicate amplification in clinical practice.

Snapshot on drug-resistance rate and profiles in patients with chronic hepatitis B receiving nucleos(t)ide analogues in clinical practice.

While the selection of complex HBV drug-resistance patterns on therapeutic failure can compromise the efficacy of anti-HBV therapies, recent data show that patients failing treatment without drug-resistance have a rate of virological success close to drug-naive patients. The goal of this study is defining, in clinical practice, the burden of drug-resistance mutations in a cohort of patients treated with anti-HBV drugs. Prevalence and patterns of drug-resistance were analyzed by RT-sequencing in 204 patients infected chronically: 148 experiencing virological rebound (defined as an increase in serum HBV-DNA > 20 IU/ml after achieving virological success [HBV-DNA < 20 IU/ml]), and 56 null/partial responders (always detectable serum HBV-DNA [>20 IU/ml] within 48 weeks of therapy). The highest rate of drug-resistance was observed in patients experiencing virological rebound (prevalence, 79.1%). Conversely, almost half (46.4%) null/partial responders have no evidence of drug-resistance. The rate of drug-resistance was higher in patients treated with lamivudine (76.8% [109/142]) and telbivudine (83.3% [5/6]), followed by adefovir (62.5% [15/24]), and entecavir (52.2% [12/23]). Complex mutational patterns characterized by the co-presence of rtM204V/I-rtA181T/V (impairing the efficacy of all anti-HBV drugs) were detected in four patients (2.7%) with virological rebound. Drug-resistance is the main cause of failure to therapy in patients experiencing virological rebound, supporting the need of rapid switch to anti-HBV drugs with higher genetic barrier and potency (entecavir/tenofovir). Conversely, nearly half of null/partial responders shows no evidence of drug-resistance mutations, maintaining high chance of achieving therapeutic success with the same class of drug. In this setting, genotypic resistance may help in selecting patients still carrying wild-type viruses, that may take major benefits from antiviral treatment.

The lowest X4 Geno2Pheno false-positive rate is associated with greater CD4 depletion in HIV-1 infected patients.

Through this study we evaluated whether the HIV-1 tropism determined by genotypic analysis correlates with HIV-1 markers, such as CD4 cell count and plasma HIV-RNA. The analysis was performed on 1221 HIV-1 B-subtype infected patients with an available V3 sequence (all maraviroc naive). Of them, 532 were antiretroviral therapy (ART) naive and 689 ART experienced. Tropism determination was performed by using the geno2pheno (co-receptor) algorithm set at a false-positive rate (FPR) of 10% and 2%. Potential associations of FPR with CD4 cell count and viraemia were evaluated. Association of V3 mutations with genotypic-determined tropism was also evaluated according to different FPR ranges. About 26% of patients (either ART naive or ART experienced) were infected by X4-tropic viruses (using the classical 10% FPR cut-off). However, a significantly lower proportion of ART-naive patients had FPR ≤ 2% in comparison with ART-experienced patients (4.9% vs. 12.6%, respectively, p <0.001). The risk of advanced HIV-1 infection (with CD4 cell count ≤ 200 cells/mm(3)) was significantly greater in X4-infected patients, either ART-naive (OR (95% CI)), 4.2 (1.8-9.2); p 0.0006) or ART-experienced (2.3 (1.4-3.6); p 0.0003), with FPR set at 2% (but not at 10%). This finding was confirmed by multivariable logistic analysis. No relationship was found between viraemia and FPR ≤2%. Some X4-related mutations were significantly associated with FPR ≤2% (ART-naive patients, S11R, Y21V, G24K and G24R, p ≤0.001; ART-experienced patients, Y7K, S11R, H13Y, p ≤0.002). In conclusion, these findings show that within the context of genotypically-assessed CXCR4 tropism, FPR ≤2% defines (far better than 10%-FPR) a viral population associated with low CD4 rank, with potentially greater cytopathic effect, and with more advanced disease.

Characterization of drug-resistance mutations in HBV D-genotype chronically infected patients, naïve to antiviral drugs.

Presence of drug-resistance mutations in drug-naïve hepatitis B virus (HBV) infected patients can seriously compromise response to antiviral treatment. Therefore, our study was aimed at defining the prevalence of HBV drug-resistance in a population of 140 patients, all infected with HBV-D-genotype (the most common HBV-genotype in Eastern Europe, Mediterranean countries and Middle East) and naïve to antiviral therapy. HBV reverse-transcriptase (RT) region was sequenced and analyzed for 20 mutations, confirmed by in vitro studies as associated with resistance to nucleos(t)ide HBV-RT inhibitors (rtL80I/V-rtI169T-rtV173L-rtL180M-rtA181T/V/S-rtT184A/S/G/C-rtA194T-rtS202C/G/I-rtM204V/I-rtN236T-rtM250V). Amino acid changes at other six RT positions, potentially associated with resistance, were also analyzed (rtV84M-rtV191I-rtV207L-rtV214A-rtQ215S-rtI233V). Overall, only 2/140 (1.4%) patients carried primary drug-resistance mutations [rtA181V (0.7%), and rtA194T (0.7%)], while 3/140 (2.1%) patients harbored the secondary mutations rtV173L (1.4%) and rtL180M (0.7%). Additionally, five polymorphic mutations, with a suggested role in drug resistance, were detected [rtQ215S (12.8%), rtI233V (4.3%), rtV214A (3.6%), rtV191I (0.7%), rtV207L (0.7%)]. Notably, no YMDD mutations, namely rtM204V/I, were found. Taken together, the rate of important drug resistance mutations in naïve HBV D-genotype infected patients is today very low, and suggests the potential full efficacy of new-generation antiviral drugs used in first line therapy. Whether such low rate can be extrapolated to non HBV-D subtypes, requires a detailed investigation to be performed in a different cohort of patients.

Successful switch to tenofovir after suboptimal response to entecavir in an immunocompromised patient with chronic hepatitis B and without genotypic hepatitis B virus resistance.

We report a case of an immunocompromised patient affected by chronic hepatitis B virus (HBV) with high basal HBV viremia (>8 log(10) IU/ml) who failed an entecavir regimen, despite the absence of primary or secondary drug resistance mutations. The patient achieved sustained virological success (serum HBV DNA <12 IU/ml) when tenofovir was added to the treatment. This case highlights the difficulty in choosing an optimal therapy in such specific conditions and supports the concept of tailoring therapy (including combination regimens) on the basis of the particular conditions of each individual patient.

Temporal change in the use of genotypic resistance testing over the years 1999--2003.

The evaluation of resistance test perception by clinicians over the years 1999--2003 was assessed in an Italian cohort. The results on 2233 samples from 1416 HIV-1 infected patients show an increase in HIV-1 drug resistance test requests over time, with a plateau reached in the last three years. CD4-cell count at the time of genotype request progressively increased. In particular, the median CD4 cell count of drug-treated patients increased from 221x10(6) cells/l [interquartile range (IQR): 109-368] in 1999 to 296x10(6) cells/l (IQR: 166-478) in 2003 (p<0.0001). At the same time, plasma HIV-RNA level progressively decreased from a median of 103,500 copies/ml (IQR: 37,250-260,000) in 1999 to 9,444 copies/ml (IQR: 2,086-41,281) in 2003 (p<0.0001). Overall, data suggest that the genotype test is increasingly considered, and requested also for patients at earlier stages of drug history and/or at less severe disease stage.