Carbohydrate-binding agents (CBAs) inhibit HIV-1 infection in human primary monocyte-derived macrophages (MDMs) and efficiently prevent MDM-directed viral capture and subsequent transmission to CD4+ T lymphocytes

Carbohydrate-binding agents (CBAs) have been proposed as innovative anti-HIV compounds selectively targeting the glycans of the HIV-1 envelope glycoprotein gp120 and preventing DC-SIGN-directed HIV capture by dendritic cells (DCs) and transmission to CD4(+) T-lymphocytes. We now show that CBAs efficiently prevent R5 HIV-1 infection of human primary monocyte-derived macrophage (MDM) cell cultures in the nanomolar range. Both R5 and X4 HIV-1 strains were efficiently captured by the macrophage mannose-binding receptor (MMR) present on MDM. HIV-1 capture by MMR-expressing MDM was inhibited by soluble mannose-binding lectin and MMR antibody. Short pre-exposure of these HIV-1 strains to CBAs is able to prevent virus capture by MDM and subsequent syncytia formation in cocultures of the CBA-exposed HIV-1-captured MDM and uninfected CD4(+) T-lymphocytes. The potential of CBAs to impair MDM in their capacity to capture and to transmit HIV to T-lymphocytes might be an important property to be taken into consideration in the eventual choice to select microbicide candidate drugs for clinical investigation.

Administration of fludarabine-loaded autologous red blood cells in simian immunodeficiency virus-infected sooty mangabeys depletes pSTAT-1-expressing macrophages and delays the rebound of viremia after suspension of antiretroviral therapy

A major limitation of highly active antiretroviral therapy is that it fails to eradicate human immunodeficiency virus (HIV) infection due to its limited effects on viral reservoirs carrying replication-competent HIV, including monocytes/macrophages (M/M). Therefore, therapeutic approaches aimed at targeting HIV-infected M/M may prove useful in the clinical management of HIV-infected patients. In previous studies, we have shown that administration of fludarabine-loaded red blood cells (RBC) in vitro selectively induces cell death in HIV-infected M/M via a pSTAT1-dependent pathway. To determine the in vivo efficacy of this novel therapeutic strategy, we treated six naturally simian immunodeficiency virus (SIV)-infected sooty mangabeys (SMs) with either 9-[2-(R)-(phosphonomethoxy)propyl]adenine (PMPA) only, fludarabine-loaded RBC only, or PMPA in association with fludarabine-loaded RBC. The rationale of this treatment was to target infected M/M with fludarabine-loaded RBC at a time when PMPA is suppressing viral replication taking place in activated CD4+ T cells. In vivo administration of fludarabine-loaded RBC was well tolerated and did not induce any discernible side effect. Importantly, addition of fludarabine-loaded RBC to PMPA delayed the rebound of viral replication after suspension of therapy, thus suggesting a reduction in the size of SIV reservoirs. While administrations of fludarabine-loaded RBC did not induce any change in the CD4+ or CD8+ T-cell compartments, we observed, in chronically SIV-infected SMs, a selective depletion of M/M expressing pSTAT1. This study suggests that therapeutic strategies based on the administration of fludarabine-loaded RBC may be further explored as interventions aimed at reducing the size of the M/M reservoirs during chronic HIV infection.

Respiratory viruses and influenza-like illness: a survey in the area of Rome, winter 2004-2005

Limited information is available on the viral aetiology of influenza-like illness (ILI) in Southern European countries. Hereby we report the main findings of a survey conducted in the area of Rome during the 2004-2005 winter season. ILI cases were defined as individuals with fever >37.5°C and at least one constitutional symptom and one respiratory symptom, recruited during the survey period. Influenza and other respiratory viruses were identified using polymerase chain reaction (PCR) on throat swabs. Basic individual information was collected through a standard form. Of 173 ILI cases enrolled, 74 tested positive for one virus, and two tested positive for two viruses. Overall, 33.5% of the cases were positive for influenza viruses, 5.2% for adenoviruses, 3.5% for parainfluenza viruses, 1.7% for coronaviruses, and 1.2% for the respiratory syncitial virus. The proportion of influenza virus detection was higher in the 'high influenza activity' period. The distribution of viral agents varied across age groups, influenza viruses being more likely to be detected in younger patients. Viral pathogens were identified in less than 50% of ILI cases occurred during a high activity influenza season. The detection of other than influenza viruses was sporadic, without evidence of large outbreaks due to specific agents.

Safety of nevirapine-containing antiretroviral triple therapy regimens to prevent vertical transmission in an African cohort of HIV-1-infected pregnant women

OBJECTIVE

To assess the incidence and consequences of adverse reactions among African HIV-positive pregnant women treated with fixed-dose combinations of a nevirapine-containing antiretroviral (ARV) triple therapy.

METHODS

A retrospective analysis of the clinical files of 703 HIV-1-positive pregnant women treated with a nevirapine-containing regimen between May 2002 and July 2004 was conducted. Selection criteria for inclusion in the analysis were: (a) taking ARV for more than 14 days; (b) baseline values of transaminases below the threshold of 2.5 times the upper limit of normal (ULN). The women were on a nevirapine-containing regimen for a median of 127 days [interquartile range (IQR) 86-190 days], starting on average at the 27th week of gestation (standard deviation+/-9.5) and continuing up to a maximum of 6 months after delivery. All women were offered formula milk to feed the babies. Highly active antiretroviral therapy (HAART) was continued beyond 6 months only if the patient qualified on the first visit. The main outcome measures were incidence of hepatotoxicity, skin rashes and Stevens-Johnson syndrome. Multivariate analysis to assess the impact of several factors on the adverse reaction rate was performed.

RESULTS

As of 1 August 2004, 554 pregnancies reached term, 96 women were still pregnant, and 53 women dropped out of the programme before giving birth. After 2 months of therapy the percentage of patients with a viral load less than 1000 HIV-1 RNA copies/mL increased to 78.6%; average CD4 cell counts increased from 490 cells/microL before therapy to 630 after therapy. The incidence of grade 3-4 adverse reactions (hepatotoxicity, skin rashes and Stevens-Johnson syndrome) was 6.5, 2.4 and 1.1%, respectively. Five women died during pregnancy (0.88%). Only one of the deaths could be associated with ARV treatment.

CONCLUSION

Nevirapine-containing regimens in pregnant woman, at all CD4 cell count levels, appear to be safe in African settings.

Key questions in antiretroviral therapy: Italian Consensus Workshop (2005)

A panel of leading Italian specialists in infectious diseases, virologists and immunologists met in Rome in 2005 to review critical data and discuss recommendations for each of the key questions in antiretroviral therapy today: When to start treatment? How to start? When to switch? What to switch to? Whether to stop or not to stop treatment, and how? The method of a nominal group meeting was used and recommendations were graded for their strength and quality using a system based on the one adopted by the Infectious Diseases Society of America. Main conclusions are summarized and critically discussed in this consensus statement, as well as some of the most recent data supporting these recommendations are provided.

Improving adherence to highly active anti-retroviral therapy in Africa: the DREAM programme in Mozambique

Ensuring high levels of adherence to highly active anti-retroviral therapy (HAART) is a priority in treating people living with AIDS. This study reports the rates of adherence of patients served by DREAM (Drug Resource Enhancement against AIDS and Malnutrition) in the city of Matola, Mozambique. DREAM, an innovative programme tailored for Africa, was implemented by the Community of Sant'Egidio in August 2001. DREAM provides patients with anti-retroviral drugs and laboratory tests at no charge, and is based on a particular strategy of health education and organization of services designed for a population that is predominantly poor and has a low level of formal education. This study analyzes the adherence of 154 patients over a period of 6 months. In evaluating adherence, two indicators were used: (1) the percentage of appointments kept for check-ups, tests and the collection of medicine, and (2) the overall change in the patients' blood chemistry over the 6-month period. Of the 154 patients, 127 (82.5%) kept more than 90% of their appointments. Adherence to the programme was further confirmed by a relevant increase of hemoglobin levels and CD4 counts, and a significant decrease in the viral loads among the 154 patients.

Respiratory viruses and influenza-like illness: a survey in the area of Rome, winter 2004-2005

Limited information is available on the viral aetiology of influenza-like illness (ILI) in Southern European countries. Hereby we report the main findings of a survey conducted in the area of Rome during the 2004-2005 winter season.ILI cases were defined as individuals with fever >37.5 degrees C and at least one constitutional symptom and one respiratory symptom, recruited during the survey period. Influenza and other respiratory viruses were identified using polymerase chain reaction (PCR) on throat swabs. Basic individual information was collected through a standard form. Of 173 ILI cases enrolled, 74 tested positive for one virus, and two tested positive for two viruses. Overall, 33.5% of the cases were positive for influenza viruses, 5.2% for adenoviruses, 3.5% for parainfluenza viruses, 1.7% for coronaviruses, and 1.2% for the respiratory syncitial virus. The proportion of influenza virus detection was higher in the 'high influenza activity' period. The distribution of viral agents varied across age groups, influenza viruses being more likely to be detected in younger patients. Viral pathogens were identified in less than 50% of ILI cases occurred during a high activity influenza season. The detection of other than influenza viruses was sporadic, without evidence of large outbreaks due to specific agents.

Multiple drug class-wide resistance associated with poorer survival after treatment failure in a cohort of HIV-infected patients

OBJECTIVE

To evaluate the effect of drug class-wide resistance (CWR) on survival in HIV-infected individuals who underwent genotypic resistance test after antiretroviral failure.

DESIGN

Observational, longitudinal cohort study.

METHODS

HIV-infected individuals experiencing treatment failure were enrolled at first genotypic resistance test. End-points were death for any cause, AIDS-related death and AIDS-defining event/death. CWR was defined according to the International AIDS Society consensus. Survival analysis was performed with Cox's model.

RESULTS

Among 623 patients enrolled and followed for a median of 19 months (interquartile range, 12-29), Kaplan-Meier analyses for end-points at 48 months in patients with no CWR, one CWR, two CWR or three CWR were 8.9, 11.7, 13.4 and 27.1%, respectively, for death; 6.1, 9.9, 13.4 and 21.5%, respectively, for AIDS-related death; and 16.0, 17.7, 19.3 and 35.9%, respectively, for new AIDS event/death. In a multivariate Cox's model, higher HIV RNA level, previous AIDS and detection of three CWR (hazard ratio, 5.34; 95% confidence interval, 1.76-16.24) were all significantly associated with increased risk of death, while higher CD4 cell count and use of a new boosted protease inhibitor drug after identifying genotypic resistance were associated with reduced risk. Detection of three CWR was also significantly associated with higher risk of AIDS-related death and new AIDS event/death.

CONCLUSIONS

Even in the late era of highly effective antiretroviral treatments, detection of CWR, particularly if extended to all three drug classes is related to poorer clinical outcome and represents a risk-marker of disease progression and death.

Updated European recommendations for the clinical use of HIV drug resistance testing

In most European countries, HIV drug resistance testing has become a routine clinical tool. However, its practical implementation in a clinical context is demanding. The European HIV Drug Resistance Panel was established to make recommendations to clinicians and virologists on this topic and to propose quality control measures. The panel recommends resistance testing for the following indications: i) drug-naive patients with acute or recent infection; ii) therapy failure, including suboptimal treatment response, when treatment change is considered; iii) pregnant HIV-1-infected women and paediatric patients with detectable viral load when treatment initiation or change is considered; and iv) genotype source patient when post-exposure prophylaxis is considered. In addition, for drug-naive patients with chronic infection in whom treatment is to be started, the panel suggests that resistance testing should be strongly considered and recommends testing the earliest sample for drug resistance if suspicion of resistance is high or prevalence of resistance in this population exceeds 10%. The panel does not favour genotyping over phenotype, however it is anticipated that genotyping will be used more often because of its greater accessibility, lower cost and faster turnaround time. For the interpretation of resistance data, clinically validated systems should be used to the greatest extent possible. It is mandatory that laboratories performing HIV resistance tests take regular part in quality assurance programs. Similarly, it is necessary that HIV clinicians and virologists take part in continuous education and meet regularly to discuss problematic clinical cases. Indeed, resistance test results should be used in the context of all other clinically relevant information for predicting therapy response. The panel also encourages the timely collection of epidemiological information to estimate the impact of transmission of resistant HIV and the prevalence of HIV-1 non-B subtypes in the different European countries.

Updated European Recommendations for the Clinical Use of HIV Drug Resistance Testing

In most European countries, HIV drug resistance testing has become a routine clinical tool. However, its practical implementation in a clinical context is demanding. The European HIV Drug Resistance Panel was established to make recommendations to clinicians and virologists on this topic and to propose quality control measures. The panel recommends resistance testing for the following indications: i) drug-naive patients with acute or recent infection; ii) therapy failure, including suboptimal treatment response, when treatment change is considered; iii) pregnant HIV-1-infected women and paediatric patients with detectable viral load when treatment initiation or change is considered; and iv) genotype source patient when post-exposure prophylaxis is considered. In addition, for drug-naive patients with chronic infection in whom treatment is to be started, the panel suggests that resistance testing should be strongly considered and recommends testing the earliest sample for drug resistance if suspicion of resistance is high or prevalence of resistance in this population exceeds 10%. The panel does not favour genotyping over phenotype, however it is anticipated that genotyping will be used more often because of its greater accessibility, lower cost and faster turnaround time. For the interpretation of resistance data, clinically validated systems should be used to the greatest extent possible. It is mandatory that laboratories performing HIV resistance tests take regular part in quality assurance programs. Similarly, it is necessary that HIV clinicians and virologists take part in continuous education and meet regularly to discuss problematic clinical cases. Indeed, resistance test results should be used in the context of all other clinically relevant information for predicting therapy response. The panel also encourages the timely collection of epidemiological information to estimate the impact of transmission of resistant HIV and the prevalence of HIV-1 non-B subtypes in the different European countries.

Variability in the Interpretation of Transmitted Genotypic HIV-1 Drug Resistance and Prediction of Virological Outcomes of the Initial Haart by Distinct Systems

High level HIV-1 drug resistance in recently infected treatment-naive individuals correlates with sub-optimal virological responses to highly active antiretroviral therapy (HAART). To determine whether genotypic HIV-1 drug resistance in chronic naive patients, as interpreted by various systems, could predict the virological outcomes of HAART, isolates from patients enrolled in a prospective observational cohort (ICoNA) prior to treatment start were genotyped. Genotypic susceptibility scores (GSS) assigned to the initial HAART regimens using the interpretations of pre-therapy resistance mutations by 13 systems were related to virological outcomes. Of 415 patients, 42 (10%) had at least one major resistance mutation. According to the different interpretations, 1.9–20.5% of patients had some level of resistance to at least one drug in the initial regimen. In multivariable analysis, GSS from two systems significantly predicted the time to virological success: Rega 5.5, for each unit increase in GSS adjusted relative hazard (RH) 1.86 [95% confidence intervals (95% CI): 1.15–3.02] and hivresistanceWeb v3, RH 1.87 (95% CI: 1.00–3.48). With three other systems, GSS showed a trend towards a significant prediction of success: Retrogram 1.6, RH 2.33 (95% CI: 0.98–5.53), Menéndez 2002, RH 2.36 (95% CI: 0.97–5.72) and Stanford hivdb, RH 2.06 (95% CI: 0.94–4.49). Genotypic resistance testing coupled with adequate interpretation in chronic naive patients can usefully identify those at risk of sub-optimal virological response to HAART.

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.

HIV/HCV co-infection: the magnitude of the problem

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) share routes of transmission, therefore their coinfection is relatively common. Nevertheless, the clinical relevance of this event has been minimal until few years ago when, due to the increased survival of HIV-infected individuals (favoured by highly active antiretroviral therapy) morbility and mortality caused by pathologies not strictly related to HIV (such as HCV infection) raised sharply. Despite differences in their general characteristics (including lifecycle, target cells, and type of persistence in the infected host) a remarkable level of interaction exists between HCV and HIV; this makes the progression of both liver disease and immunological damage easier and more rapid. A therapeutic approach to HIV/HCV coinfection thus requires the utilization of drugs and strategies effective against both viruses, yet, timing, drug types, and effective combinations still remain poorly defined. New and innovative studies specifically focused on HIV/HCV coinfection are thus warranted to increase the knowledge about their interaction, and define therapeutic strategies aimed to the best management of the infection by both viruses during coinfection.

Cross-resistance among nonnucleoside reverse transcriptase inhibitors limits recycling efavirenz after nevirapine failure

Heterogeneity in genotype mutations associated with resistance of HIV to nonnucleoside reverse transcriptase inhibitors (NNRTIs) should allow identification of patients failing nevirapine (NVP) who might benefit from efavirenz (EFV)-containing salvage regimens. To establish the feasibility of recycling EFV after failure of NVP-containing regimens genotypic data on 103 NVP-failed patients were analyzed to evaluate the prevalence of EFV resistance-conferring mutations. A clinically significant resistance to EFV was found in 50 of 103 (58%) of NVP-failed subjects. Furthermore, the 3-month virological response to salvage regimens containing EFV was assessed in patients previously treated with NVP and carrying single mutations conferring resistance to this drug. A proportion of HIV RNA less than 500 copies/ml at 3 months was obtained only in 2 of 12 (17%) of EFV-treated subjects compared with 35 of 67 (52%) of those without NNRTI mutations (OR, 0.18; 95% CI, 0.03-0.79). The median HIV-1 RNA decrease after 3 months was -0.63 log(10) among patients carrying single NNRTI-associated mutations compared with -1.32 log(10) among those without any NNRTI mutations. No virological response was observed in six patients harboring a single Y181C/I mutation. On the basis of the present data, sequential use of NNRTIs should be avoided in the management of treatment failure.

Factors related to virologic failure among HIV-positive injecting drug users treated with combination antiretroviral therapy including two nucleoside reverse transcriptase inhibitors and nevirapine

Treatment strategies in human immunodeficiency virus (HIV)-positive active injecting drug users (IDUs) must take into account their lifestyles, that often result in low adherence to therapy. The nonnucleoside reverse transcriptase inhibitors (NNRTI) offer simpler treatment regimens, but the appearance of drug resistance during treatment failure may cause high levels of cross-resistance to all NNRTIs. We adopted a combination therapy of two NRTIs and nevirapine (NVP) for treatment of IDU patients to evaluate its feasibility in such patients. From October 1998 to December 1999, demographic, clinical, and laboratory data from 80 IDUs on this regimen were collected. Fisher's exact test, Kaplan Meier method, and Cox model were used for statistical analysis. Overall, 20 IDUs discontinued the treatment because of side effects and 20 IDUs experienced treatment failure. Considering the treatment failure as an end point, 55.6% (95% confidence interval [CI]: 37.9%-72.6%) of patients was still undergoing treatment after 12 months compared to 44.6% (31.8%-58.6%) when discontinuation was also taken into account. An increasing trend over time was observed in the CD4+ lymphocyte count, among failing and nonfailing IDUs. By multivariate analysis, baseline HIV-RNA, treatment breaks and low adherence and active injecting drug use turned out to be significantly associated with treatment failure. Our results show that continuing injecting drug use and treatment breaks are the main factors that can lead to treatment failure in IDUs and easily to NNRTI class resistance.

Primary HIV-1 resistance in recently and chronically infected individuals of the Italian Cohort Naive for Antiretrovirals

The risk of acquiring HIV-1 drug resistance at time of infection has become a public health problem following the widespread use of antiretroviral drugs in developed countries. Although a number of studies have reported data regarding the prevalence of HIV-1 primary resistance in developed countries over the past years, limited knowledge is available regarding the proportion of mutations related to drug resistance in antiretroviral naive subjects with chronic HIV-1 disease. In this study, we evaluated the prevalence of mutations in the reverse-transcriptase (RT) and protease region both in a representative group of recently HIV-1 infected subjects (n=68) and a cohort of chronically-infected HIV-positive patients (n=347) enrolled in the Italian Cohort of Antiretroviral Naive patients (I.CO.NA.). In recently infected individuals, the overall prevalence of mutations for nucleoside RTI (NRTIs) was 10/68 (14.7%). The distribution of mutations by calendar year were 0, 1 in 1996, 9, 3 in 1997 and 1, 0 in 1998 for NRTIs and protease inhibitors (PIs) respectively. Thymidine associated mutations were identified in six subjects (8.8%), five of whom had one mutation [41L, 70K (n=2), 215Y] and one had two mutations (67N+219Q). Four subjects (5.9%) showed the changes associated with resistance to lamivudine (184V or 118I). No non nucleoside-RTI (NNRTI) mutations were present in the study period. Primary PIs mutations (two 46L and two 82I) were present in four subjects (5.9%). Of note, mutations related to resistance to more than one class of antiretrovirals were present in one (1.5%). Among patients with chronic infection a large proportion (88.5%) carried no mutations in RT region, 11.5% individuals carried one or more mutations associated with resistance to NRTI (7.8%), or NNRTI (4.9%), with 4 patients carrying mutations to both classes. Among mutations associated with high-level resistance to RTI, T215Y was found in only 2 patients, M184V in 2 cases, T69D in another case, and K103N in only 1 patient, for a total of 6 patients (one carrying both T215Y and M184V) (1.7%). Primary mutations associated with substantial resistance to PIs were found in only 5/347 patients (1.4%); all the other patients carried only secondary mutations. Prevalence of mutations associated with high-level resistance to antiretroviral drugs is stable in recently infected individuals and low in patients with established HIV infection. The potential impact of transmitted mutations on the response to first regimen in individuals carrying transmitted mutations needs to be assessed by prospective studies.

Secondary mutations in the protease region of human immunodeficiency virus and virologic failure in drug-naive patients treated with protease inhibitor-based therapy

The role of mutations in protease (PR) and reverse-transcriptase (RT) of human immunodeficiency virus (HIV) in predicting virologic failure was assessed in 248 antiretroviral-naive HIV-positive patients who began a PR inhibitor-containing antiretroviral regimen. Genotypic testing was performed on plasma samples stored before the start of therapy. Twenty-seven patients (10.9%) had mutations in the RT, 5 (2%) carried primary mutations in the PR, and 131 (52.8%) showed only secondary PR mutations. Virologic failure at week 24 occurred in 62 (25.0%) of 248 patients. There was a statistically significant correlation between virologic failure and the number of PR mutations (P= .04, chi(2) test). Mutations at codons 10 and 36 of PR (present in 39.3% and 40.0% of patients in whom treatment failed, respectively) were identified by stepwise logistic regression as the strongest predictors of virologic failure (odds ratio, 2.20; 95% confidence interval, 1.30-3.75; P= .004). If confirmed in independent studies, this result may justify the increased use of HIV genotyping in drug-naive patients requiring antiretroviral therapy.

Increasing prevalence of non-clade B HIV-1 strains in heterosexual men and women, as monitored by analysis of reverse transcriptase and protease sequences

OBJECTIVE

We evaluated the prevalence of HIV-1 non-clade B over time in a formerly clade B-restricted area. Protease and reverse transcriptase regions of the pol gene were used for phylogenetic and recombination analysis and for clade assignment to HIV-1 A-D, F-H, J, and K strains of the M group.

METHODS

The pol gene of 349 HIV-1 patients belonging to the Italian Cohort Naive for Antiretrovirals (ICONA) were genotypically analyzed to study the prevalence of antiretroviral-associated resistance mutations. All HIV-1 pol sequences and 32 HIV reference strains were analyzed, including the reference strains for the major HIV-1 subtypes. The non-clade B sequences according to the HIV-1 Subtyping Tool program were further studied by a bootscan analysis (SimPlot) to investigate the likelihood of recombination between subtypes.

RESULTS

Phylogenetic analysis detected 19 of 349 (5.4%) non-clade B subtypes. The proportions of patients carrying non-clade B virus before and after 1997 were 1.9% and 8.4%, respectively (p =.008). Among whites, heterosexual infection and female gender were significantly associated with the presence of non-clade B subtypes (p =.001 and.005, respectively). Non-clade B HIV-1 was harbored by 14.5% of the heterosexuals who were found to be HIV-1 positive after 1997, 60% of whom were women. Bootscan analysis identified four strains as F, two as A, one as C, one as G, and 11 (57.9 %) as non-clade B recombinant subtypes.

CONCLUSION

Detection of HIV-1 subtypes and intersubtype recombinants in a previously clade B-homogeneous area indicates that the HIV-1 epidemic is evolving in Italy and that heterosexuals and women are at increased risk of infection with non-clade B HIV-1 subtypes. Sequences inferred from the pol gene yield to establish the subtype of circulating HIV-1 strains. As a consequence, genotyping of pol gene for testing resistance to antiretrovirals warrants concomitant surveillance of non-clade B subtypes.

The potency of acyclovir can be markedly different in different cell types

Acyclovir is an acyclic guanine analog with a considerable activity against herpes simplex viruses. We studied the antiherpetic activity of acyclovir in macrophages and fibroblast cell lines. Utilising a plaque reduction assay we found that acyclovir potently inhibited the HSV-1 replication in macrophages (EC50) = 0.0025 microM) compared to Vero (EC50 = 8.5 microM) and MRC-5 (EC50 = 3.3 microM) cells. The cytotoxicity of acyclovir was not detected at concentrations < or = 20 microM, thus the selective index in macrophages was >8000. This marked difference in antiherpetic activity between macrophages and fibroblasts was not observed with Foscarnet and PMEA. We suggest that this potent antiviral effect of acyclovir is mainly due to a proficient phosphorylation of the drug and/or a favourable dGTP/acyclovir triphosphate ratio in macrophage cells.

Exploitation of the low fidelity of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and the nucleotide composition bias in the HIV-1 genome to alter the drug resistance development of HIV

The RNA genome of the lentivirus human immunodeficiency virus type 1 (HIV-1) is significantly richer in adenine nucleotides than the statistically equal distribution of the four different nucleotides that is expected. This compositional bias may be due to the guanine-to-adenine (G-->A) nucleotide hypermutation of the HIV genome, which has been explained by dCTP pool imbalances during reverse transcription. The adenine nucleotide bias together with the poor fidelity of HIV-1 reverse transcriptase markedly enhances the genetic variation of HIV and may be responsible for the rapid emergence of drug-resistant HIV-1 strains. We have now attempted to counteract the normal mutational pattern of HIV-1 in response to anti-HIV-1 drugs by altering the endogenous deoxynucleoside triphosphate pool ratios with antimetabolites in virus-infected cell cultures. We showed that administration of these antimetabolic compounds resulted in an altered drug resistance pattern due to the reversal of the predominant mutational flow of HIV (G-->A) to an adenine-to-guanine (A-->G) nucleotide pattern in the intact HIV-1-infected lymphocyte cultures. Forcing the virus to change its inherent nucleotide bias may lead to better control of viral drug resistance development.

Oxidative stress and neuroAIDS: triggers, modulators and novel antioxidants

Neurological disorders represent one of the most common disturbances accompanying HIV infection. In the past few years, highly antiretroviral active therapy has significantly reduced the incidence of HIV-related diseases. However, neurological dysfunction in AIDS patients still remains an unresolved problem. Oxidative stress, which occurs in brain tissues of patients undergoing HIV infection and is implicated in cell death of both astroglia and neurones, has recently been suggested to play a role in the pathogenesis of neuroAIDS. Thus, a better understanding of the processes that trigger and modulate free radical formation in brain tissues of AIDS patients might help in a successful therapeutic approach to the neuropathogenesis of HIV infection.

Macrophages: a crucial reservoir for human immunodeficiency virus in the body

The replication of Human Immunodeficiency Virus (HIV) in cells of macrophage lineage represents a key pathogenetic event of the neurological damages typically found during the course of this disease. Macrophages are persistently infected cells and thus not susceptible to the cytophatic effect typical of infected activated CD4-lymphocytes. The resistance of macrophages to HIV infection is at least in part mediated by the autocrine production of the nerve growth factor (NGF), a neurokine able to sustain the survival of some cells of bone marrow origin, including monocyte-derived macrophages. This anti-apoptotic effect of NGF in HIV-infected macrophages can be even more relevant at the central nervous system level, where many cells are able to physiologically produce NGF, thus further increasing the survival of macrophages infected by HIV, and enhancing the damages that these cells may induce upon bystander neurons. The proapoptotic effect of soluble factors released by HIV-infected macrophages may heavily affect the survival and functions also of astrocytes, that in turn become unable to sustain neuronal homeostasis. Taken together, this information supports the importance of therapeutic attempts aimed at attacking virus replication in infected macrophages and/or to selectively eliminate these chronically infected and persistently virus-producing cells.

Erythrocyte-mediated delivery of a new homodinucleotide active against human immunodeficiency virus and herpes simplex virus

Monocyte-derived macrophages (MDMs) play a central role in the pathogenesis of infection by human immunodeficiency virus (HIV-1) and represent one of the main reservoirs of the virus in the body. In addition, MDMs can easily be infected by various herpes viruses, including herpes simplex virus type 1 (HSV-1). We have synthesized a new antiviral agent (Bis-PMEA) that consists of two 9-(2-phosphonylmethoxyethyl)adenine (PMEA) molecules bound by a phosphate bridge. This nucleotide analogue, like the parent compound PMEA, has strong and selective activity against HIV-1 and HSV-1. A drug-targeting system previously developed in our laboratory was used for the selective delivery of these drugs to macrophages. Bis-PMEA and PMEA were encapsulated into autologous erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. Loaded erythrocytes were modified to increase their recognition and phagocytosis by human macrophages. By administering Bis-PMEA-loaded erythrocytes to macrophages, 47% of Bis-PMEA and 28% of PMEA was still present 10 days after phagocytosis; in contrast, only 12% of PMEA was found in macrophages receiving PMEA-loaded erythrocytes. Bis-PMEA-loaded erythrocytes were then added to macrophages infected with HIV-1 and HSV-1 and their antiviral activity evaluated. Remarkable protection was obtained against HIV-1 and HSV-1 infection (95 and 85%, respectively). Therefore, Bis-PMEA acts as an efficient antiviral prodrug that, following selective targeting to macrophages by means of loaded erythrocytes, can protect a refractory cell compartment.

Inhibition of HIV-1 replication in macrophages by red blood cell-mediated delivery of a heterodinucleotide of azidothymidine and 9-(R)-2-(phosphono methoxypropyl)adenine

Monocyte-derived macrophages (M/M) are considered important in vivo reservoirs for different kinds of viruses, including HIV. Hence, therapeutic strategies are urgently needed to protect these cells from virus infection or to control viral replication. In this paper, we report the synthesis, target delivery and in vitro efficacy of a new heterodinucleotide (AZTpPMPA), able to inhibit HIV-1 production in human macrophages. AZTpPMPA consists of two established anti-HIV drugs [zidovudine (AZT) and tenofovir (PMPA)] chemically coupled together by a phosphate bridge. This drug is not able to prevent p24 production when administered for 18 h to M/M experimentally infected with HIV-1 Bal (inhibition 27%), but can almost completely suppress virus production when given encapsulated into autologous erythrocytes (inhibition of p24 production 97%). AZTpPMPA is slowly converted to PMPA, AZT monophosphate and AZT (36 h half-life at 37 degrees C) by cell-resident enzymes. Thus AZTpPMPA should be considered a new prodrug of AZT and PMPA that is able to provide stechiometric amounts of both nucleoside analogues to macrophage cells and to overcome the low phosphorylating activity of M/M for AZT and the modest permeability of PMPA.

Cyclosaligenyl-2',3'-didehydro-2',3'-dideoxythymidine monophosphate: efficient intracellular delivery of d4TMP

Cyclosaligenyl-2',3'-didehydro-2', 3'-dideoxythymidine-5'-monophosphate (cycloSal-d4TMP) is a potent and selective inhibitor of human immunodeficiency virus replication in cell culture and differs from other nucleotide prodrug approaches in that it is designed to selectively deliver the nucleotide 5'-monophosphate by a controlled, chemically induced hydrolysis. Its antiviral efficacy in cell culture is at least as good as, if not superior to, that of d4T. CycloSal-d4TMP was found to lead to the efficient intracellular release of d4TMP in a variety of cell lines, including both wild-type CEM and thymidine kinase-deficient CEM/TK(-) cells. Under similar experimental conditions, exposure of CEM/TK(-) cells to d4T failed to result in significant d4TTP levels. The intracellular conversion of cycloSal-d4TMP proved to be both time and dose dependent. The half-life of d4TTP generated intracellularly from d4T- or cycloSal-d4TMP-treated CEM cells was approximately 3.5 h, and the intracellular ratios of d4TTP/d4TMP in cells exposed to cycloSal-d4TMP gradually increased from 1 to 3.4 upon prolonged incubation. Radiolabeled cycloSal-d4TMP could be separated as its two R(p) and S(p) diastereomers on high-performance liquid chromatography. The R(p) diastereomer of cycloSal-d4TMP was 3- to 7-fold more efficient in releasing d4TMP and generating d4TTP than the S(p) cycloSal-d4TMP diastereomer. This correlated well with the 5-fold more pronounced antiviral activity of the R(p) diastereomer versus the S(p) diastereomer. d4TMP is a poor substrate for the cytosolic 5'(3')-deoxyribonucleotidase (V(max)/K(m) for d4TMP: 0.08 of V(max)/K(m) for dTMP) and is only slowly hydrolyzed to d4T. This contributes to the efficient conversion of the prodrug of d4TTP.

Primary macrophages infected by human immunodeficiency virus trigger CD95-mediated apoptosis of uninfected astrocytes

Infection of macrophages (M/M) by human immunodeficiency virus (HIV) is a main pathogenetic event leading to neuronal dysfunction and death in patients with AIDS dementia complex. Alteration of viability of neurons and astrocytes occurs in vivo even without their infection, thus it is conceivable that HIV-infected M/M may affect viability of such cells even without direct infection. To assess this hypothesis, we studied the effects of HIV-infected M/M on an astrocytic cell-line lacking CD4-receptor expression. Exposure to supernatants of HIV-infected M/M triggers complete disruption and apoptotic death of astrocytic cells. This effect is not related to HIV transmission from infected M/M, because HIV-DNA and p24 production in astrocytic cells remained negative. Apoptotic death of astrocytes is mainly mediated by Fas ligand released in supernatants of HIV-infected M/M (as demonstrated by complete reversal of such phenomenon by adding neutralizing antibodies against CD95 receptor). Treatment of astrocytic cells with recombinant (biologically active) Tat induces < 10% apoptosis, and gp120 was totally ineffective. Treatment of HIV-infected M/M with AZT completely reverses the proapoptotic effect of their supernatants on astrocytes, thus demonstrating that productive virus replication within M/M is required for the induction of astrocytic cell death. Taken together, data suggest that homeostasis of astrocytes may be affected by HIV-infected M/M in the absence of productive infection of target cells. This phenomenon may help to explain the cellular damage found in HIV-infected patients also in areas of the brain not strictly adjacent to HIV-infected M/M.

Presence of 2',5'-Bis-O-(tert-butyldimethylsilyl)-3'-spiro-5"-(4"-amino-1",2"-oxath iole-2",2"-dioxide) (TSAO)-resistant virus strains in TSAO-inexperienced HIV patients

HIV-1 samples from six patients undergoing diverse anti-HIV therapies possessed the E138A mutation in their reverse transcriptase (RT) genome. Patients were receiving the following therapies: TIBO monotherapy (one patient); zidovudine plus didanosine combination therapy (one); zidovudine monotherapy (one); sequential therapy with zidovudine, then stavudine and finally zalcitabine plus didanosine (one); and two were drug naive. E138K, not E138A, is a known TSAO-specific resistance mutation, emerging under selective pressure in vitro. Our phenotypic data on the patient isolates, confirmed by data on an E138A mutant acquired through in vitro mutagenesis, indicated that an alanine substitution for glutamate at codon 138 of the HIV-1 RT renders the virus TSAO resistant, confirming the importance of this amino acid residue in the activity of TSAO derivatives. In addition, we have demonstrated through phenotypic analysis of the E138A and A98S mutants (after in vitro mutagenesis) that the mutation A98S, found in one of these patients, could be partially responsible for the phenotypic reversal of TSAO resistance. This reversal could be explained by the restoration of a hydrogen bond between 98S and the main-chain residue L349, which compensates for the loss of the E138-G99 main-chain hydrogen bond. As TSAO derivatives have not been used in the clinical setting, the presence of the E138A mutation at a frequency of 6.7% in our study of 90 TSAO-inexperienced HIV-seropositive individuals implies that 138A of the RT must be a natural variant and that the mutant virus is replication competent. Our observations suggest that the E138A mutation may likely arise in patients under the selective pressure of TSAO or related compounds that show a decreased antiviral potency toward the E138A variant.

Viral dynamics and mutations in the pol gene during primary HIV-1 infection

The understanding of viral dynamics and appearance of mutations during primary infection could be useful for the design of an efficient therapy. For this reason a cohort of samples from naive primary patients was examined. The results pointed out that only a few secondary mutations in protease gene (having no effect on resistance) were found, while a single mutation conferring resistance to non-nucleosides inhibitors of reverse transcriptase was found both in plasma and cerebrospinal fluid of a patient. As both the protease secondary mutations and the single non nucleoside reverse transcriptase mutation map far from the catalytical sites of the enzymes, neither one is able to impair viral fitness. Overall data suggest that treated donors carrying resistant strains may be in part unable to transfer them to the recipient, and/or virus in the recipient tends to revert to wild type. These results should be taken into account in the planning of early HAART treatment of HIV infection.

Activities of masked 2',3'-dideoxynucleoside monophosphate derivatives against human immunodeficiency virus in resting macrophages

The anti-human immunodeficiency virus (HIV) activity of aryloxyphosphoramidate protides of a number of anti-HIV nucleoside analogues was assessed in resting primary monocyte-macrophages (M/M). While 2',3'-dideoxythymidine (d4T), 2',3'-dideoxyadenosine (ddA), and 2',3'-dideoxy-2',3'-didehydroadenosine (d4A) protides showed an anti-HIV activity that was 25- to 625-fold greater than the parent nucleotides d4T, ddA, and d4A, respectively, other aryloxyphosphoramidate protides showed similar or even lower anti-HIV activities than their parent compounds. This variable anti-HIV effect is most likely related to the different dynamics of intracellular nucleoside monophosphate release from the protides. Our results indicate the potential advantage of therapeutic use of this approach for some nucleotide analogues to affect HIV replication in M/M, one of the major reservoirs of HIV in vivo.

Obstructive biliary symptomatology as the first sign of HIV-infection

A 41-year-old white homosexual man presented with epigastric pain and jaundice. Physical examination showed enlargement of bilateral axillar and left inguinal lymph node, while ERCP and a CT scan suggested interruption of bile flow in the intrapancreatic tract of the common bile duct. An endoprosthesis was positioned in the common bile duct during the ERCP. Blood tests (both ELISA and Western blot techniques) showed positivity for anti-HIV antibodies and a CD4 count of 780/mmc (normal: 900-1,200/mmc). A few days later, a dramatic increase of the size of a lymph node in this right axilla occurred, rapidly reaching 5 cm of diameter. A biopsy was performed at this level, and histological examination revealed a high grade B-cell Burkitt type lymphoma. Bone marrow biopsy was negative, as well as lumbar puncture. Aggressive chemotherapy with adriamycin, cyclophosphamide, bleomycine, eldesine and prednisone, together with intratechal administration of methotrexate, was attempted. However, after a marginal and transient regression, the NHL rapidly progressed and the patient eventually died seven months after the diagnosis of NHL. A post mortem examination confirmed the diagnosis of Burkitt lymphoma of the peripancreatic and axillar lymph nodes, with diffusion to the leptomeninges, subaracnoideal spaces and encephalus. No signs of lymphoma were detected in other nodal or extra nodal areas.

Nerve growth factor is an autocrine factor essential for the survival of macrophages infected with HIV

Nerve growth factor (NGF) is a neurotrophin with the ability to exert specific effects on cells of the immune system. Human monocytes/macrophages (M/M) infected in vitro with HIV type 1 (HIV-1) are able to produce substantial levels of NGF that are associated with enhanced expression of the high-affinity NGF receptor (p140 trkA) on the M/M surface. Treatment of HIV-infected human M/M with anti-NGF Ab blocking the biological activity of NGF leads to a marked decrease of the expression of p140 trkA high-affinity receptor, a concomitant increased expression of p75(NTR) low-affinity receptor for NGF, and the occurrence of apoptotic death of M/M. Taken together, these findings suggest a role for NGF as an autocrine survival factor that rescues human M/M from the cytopathic effect caused by HIV infection.

Synthesis and biological application of a new heterodinucleotide with both anti-HSV and anti-HIV activity

A new antiviral drug with both anti-HSV and anti-HIV activity was synthesized by coupling Acyclovir and the acyclic nucleoside phosphonate (R)PMPA. The heterodinucleotide ACVpPMPA encapsulated into autologous erythrocytes was added to human macrophages providing an effective in vitro protection from HSV-1 and HIV-1 replication.

Clinical implications of HIV dynamics and drug resistance in macrophages

Macrophages are widely recognized as the second major target of HIV in the body. The cellular characteristics of such resting cells markedly affect the dynamics of virus lifecycle, that is slower but far more prolonged that in lymphocytes. In addition, the limited concentrations of endogenous nucleotide pools in macrophages downregulate the enzymatic activity of reverse transcriptase. As a consequence, both the anti-HIV activity and the development of resistance to antiviral drugs in macrophages are substantially different than those found in activated lymphocytes. These peculiar characteristics of virus replication and efficacy of antiviral drugs in macrophages have a natural in vivo counterpart in extralymphoid tissues, where macrophages account for the majority of cells infected by HIV. Furthermore, the replication of HIV in macrophages of testis and central nervous system is far less affected by antiviral drugs than in lymph nodes, because of the presence of natural barriers that markedly diminish the concentration of such drugs. For all these reasons, HIV infection of macrophages should be taken into account in therapeutic strategies aimed to achieve an optimal therapeutic effect in all tissue compartments where the virus hides and replicates.

Relative potency of protease inhibitors in monocytes/macrophages acutely and chronically infected with human immunodeficiency virus

The activity of three human immunodeficiency virus (HIV) protease inhibitors was investigated in human primary monocytes/macrophages (M/M) chronically infected by HIV-1. Saquinavir, KNI-272, and ritonavir inhibited the replication of HIV-1 in vitro, with EC50s of approximately 0.5-3.3 microM. However, only partial inhibition was achievable, even at the highest concentrations tested. Also, the activity of these drugs in chronically infected M/M was approximately 7- to 26-fold lower than in acutely infected M/M and approximately 2- to 10-fold lower than in chronically infected H9 lymphocytes. When protease inhibitors were removed from cultures of chronically infected M/M, production of virus rapidly returned to the levels found in untreated M/M. Therefore, relatively high concentrations of protease inhibitors are required to suppress HIV-1 production in chronically infected macrophages, and such cells may be a vulnerable point for the escape of virus in patients taking these drugs.

Macrophage protection against human immunodeficiency virus or herpes simplex virus by red blood cell-mediated delivery of a heterodinucleotide of azidothymidine and acyclovir

Human herpesvirus (HSVs) are distributed worldwide and are among the most frequent causes of viral infection in HIV-1-immunocompromised patients. Hence, therapeutic strategies able to inhibit HSV-1 and HIV-1 replication are sorely needed. Until now, the most common therapies against HSV-1 and HIV-1 infectivity have been based on the administration of nucleoside analogs; however, to be active, these antiviral drugs must be converted to their triphosphorylated derivatives by viral and/or cellular kinases. At the cellular level, the main problems involved in the use of such drugs are their limited phosphorylation in some cells (e.g., antiretroviral drugs in macrophages) and the cytotoxic side effects of nucleoside analog triphosphates. To overcome these limitations, a new heterodinucleotide (AZTp2ACV) consisting of both an antiretroviral and an antiherpetic drug, bound by a pyrophosphate bridge, was designed and synthesized. The impermeant AZTp2ACV was encapsulated into autologous erythrocytes modified to increase their recognition and phagocytosis by human macrophages. Once inside macrophages, metabolic activation of the drug occurred. The addition of AZTp2ACV-loaded erythrocytes to human macrophages provided effective and almost complete in vitro protection from HIV-1 and HSV-1 replications, respectively. Therefore, AZTp2ACV acts as an efficient antiviral prodrug following selective targeting to macrophages by means of loaded erythrocytes.

[Correlation between HIV-inhibiting drug activity in human macrophages and clinical outcome]

PURPOSE

To assess the comparative efficacy of drugs inhibitors of human immunodeficiency virus (HIV) in human macrophages and lymphocytes, and to correlate the results with the clinical outcome.

MATERIALS AND METHODS

Human primary macrophages and lymphocytes were infected with HIV in the presence of the following HIV inhibitors, all currently in clinical use: zidovudine, stavudine, zalcitabine, didanosine, lamivudine, PMEA, PMPA (all inhibitors of HIV reverse transcriptase), saquinavir and U-75875 (inhibitors of HIV protease).

RESULTS

All reverse transcriptase inhibitors tested showed a markedly higher antiviral activity in macrophages than in lymphocytes. Also protease inhibitors have a substantial anti-HIV activity in macrophages, yet their efficacy is markedly diminished if the drugs are added to macrophage culture after HIV, that is when the virus has established a chronical infection. Under these experimental conditions, however, only protease inhibitors among all HIV-inhibitors in clinical use are able to decrease virus replication in chronically-infected macrophages.

CONCLUSIONS

The results have strong clinical implications, due to the important role of macrophages in the pathogenesis of HIV infection. Macrophages are the major source of HIV at extralymphoid tissue levels, particularly in the central nervous system, where the blood-brain barrier strongly limits the penetration of antiviral drugs. For these reasons, only drugs, like stavudine and zidovudine, provided with good anti-HIV activity in macrophages, and reasonable barrier penetration have substantial chances to be effective in the central nervous system, and thus affect virus replication in a sanctuary where HIV hides and replicates out of the control of the immune system.

S-adenosylhomocysteine hydrolase inhibitors interfere with the replication of human immunodeficiency virus type 1 through inhibition of the LTR transactivation

Various analogues of adenosine have been described as inhibitors of S-adenosylhomocysteine (AdoHcy) hydrolase, and some of these AdoHcy hydrolase inhibitors (e.g., 3-deazaadenosine, 3-deazaaristeromycin, and 3-deazaneplanocin A) have also been reported to inhibit the replication of human immunodeficiency virus type 1 (HIV-1). When evaluated against HIV-1 replication in MT-4 cells, macrophages, or phytohemagglutinin-stimulated peripheral blood lymphocytes infected acutely or chronically with HIV-1IIIB or HIVBaL strains, a wide range of adenosine analogues did not inhibit HIV-1IIIB replication for 50% at subtoxic concentrations. However, they inhibited HIV-1 replication in HeLa CD4+ LTR-LacZ cells at concentrations well below cytotoxicity threshold. A close correlation was found among the inhibitory effect of the compounds on AdoHcy hydrolase activity, their inhibition of HIV-1 replication in Hela CD4+ LTR-LacZ cells, and their inhibition of the HIV-1 Tat-dependent and -independent transactivation of the long terminal repeat, whereas no inhibitory effect was seen on HIV-1 reverse transcription or a Tat-independent cytomegalovirus promoter. Our results suggest that AdoHcy hydrolase and the associated S-adenosylmethionine-dependent methylation mechanism play a role in the process of long terminal repeat transactivation and, hence, HIV replication.

Inhibition of replication of HIV in primary monocyte/macrophages by different antiviral drugs and comparative efficacy in lymphocytes

Several anti-HIV drugs acting on different steps of virus replication were tested in our experimental model of primary monocyte/macrophages; the results were compared with the activity found in lymphocytes. Nucleoside analogues (AZT, ddI, ddC, d4T, PMEA, 3TC etc.) show greater activity in macrophages (M/M) than in lymphocytes. In particular, the EC50 of AZT, ddC, and ddI in M/M is 2- to 100-fold lower than that found in lymphocytes. This greater efficacy of nucleoside analogues in M/M depends on the enhancement of their chain-terminating activity by the low levels of endogenous deoxynucleoside-triphosphates (dNTP) usually found in resting cells such as M/M. Non-nucleoside reverse transcriptase inhibitors (NNRTI) do not act as chain terminators (thus their antiviral effect is not related to the intracellular concentrations of dNTP); as a consequence the activity of TSAO, HEPT, TIBO, and other NNRTI tested in M/M is similar to that found in lymphocytes. Regarding inhibitors of binding and fusion of HIV, we found that their anti-HIV activity is markedly decreased (or even nullified) when M/M are treated with cytokine activators of M/M function and enhancers of HIV replication. More relevant from a clinical standpoint, protease inhibitors are able to inhibit HIV replication in chronically infected macrophages (i.e., cells carrying the proviral genome already integrated in the host genome). All other inhibitors of late stage of virus life cycle tested (antisense-rev, anti-tat, interferon-alpha and -gamma, phosphorothioate analogues, GLQ-223, etc.) were totally inactive in chronically infected macrophages. The different effects of various classes of HIV inhibitors in lymphocytes and macrophages suggests that AIDS therapy should consider all aspects of the pathogenesis of HIV infection and must be restricted to drugs, or combinations of drugs, active against both lymphocytes and M/M in all body compartments where the virus hides and replicates.

Conversion of 2',3'-dideoxyadenosine (ddA) and 2',3'-didehydro-2',3'-dideoxyadenosine (d4A) to their corresponding aryloxyphosphoramidate derivatives markedly potentiates their activity against human immunodeficiency virus and hepatitis B virus

2',3'-Dideoxyadenosine (ddA), 2',3'-didehydro-2',3'-dideoxyadenosine (d4A) and their lipophilic 5'-monophosphate triester (aryloxyphosphoramidate) prodrugs were evaluated for their anti-retrovirus and anti-hepatitis B virus activity in various cell culture models. The aryloxyphosphoramidate derivatives of ddA (Cf 1093) and d4A (Cf 1001) showed markedly superior (100-1000-fold) efficacies than the parent drugs against human immunodeficiency virus type 1 (HIV-1), HIV-2, simian immunodeficiency virus (SIV), Moloney murine sarcoma virus (MSV) and human hepatitis B virus (HBV) replication regardless of the cell type in which the virus replication was studied (i.e., human T-lymphocyte CEM, MT-4, Molt/4 and C8166 cells, peripheral blood lymphocytes (PBL), monocyte/macrophages (M/M), murine embryo fibroblasts and human hepatocyte cells). Also the selectivity index (ratio of cytotoxic concentration/antivirally effective concentration) of both aryloxyphosphoramidate prodrugs was markedly increased. In particular the d4A prodrug Cf 1001 showed a selectivity index of 300-3000 as compared with 2-3 for the parental d4A in established laboratory cell lines. Also Cf 1001 had a selectivity index of 400-650 in HIV-1-infected PBL and M/M, respectively. Both Cf 1001 and Cf 1093 were equally efficient as 3TC (lamivudine) in inhibiting HBV replication in hepatocytes, and rank among the most potent HIV and HBV inhibitors reported so far in cell culture.

Red blood cells mediated delivery of 9-(2-phosphonylmethoxyethyl)adenine to primary macrophages: efficiency metabolism and activity against human immunodeficiency virus or herpes simplex virus

Red blood cells (RBC) may act as selective carriers of drugs to macrophages, an important reservoir of viruses such as human immunodeficiency virus (HIV) and herpes simplex virus type 1 (HSV-1). We therefore assessed the incorporation of 9-(2-phosphonylmethoxyethyl)adenine (PMEA), a potent inhibitor of HIV and HSV-1) into RBC, its delivery to macrophages and its activity against HIV or HSV-1. Loading of PMEA in artificially aged opsonized RBC affords significant levels of intracellular PMEA. RBC metabolize PMEA to its active congener PMEA-diphosphate, although with low efficiency. Exposure of macrophages to RBC-encapsulated PMEA inhibits the replication of both HIV and HSV-1 (about 90% inhibition at the highest RBC:macrophages ratios) even if RBC were removed before virus challenge. By contrast, the antiviral activity of free PMEA removed before virus challenge was irrelevant at concentrations up to 150-fold higher than the 50% effective concentration (EC50). Finally, the antiviral effect of RBC-encapsulated PMEA correlates with PMEA levels in macrophages about 500-fold higher than those achieved by free PMEA (at concentrations 10-fold higher than the EC50). The efficacy of RBC-mediated delivery to macrophages of PMEA (and perhaps of compounds with shorter intracellular half-lives) warrants further studies in infectious diseases involving phagocytizing cells as main targets of the pathogen.

HIV infection in macrophage: role of long-lived cells and related therapeutical strategies

Therapeutical strategies aimed to the maximal inhibition (if not the eradication) of infection by human immunodeficiency virus should take into account the issue of the viral reservoir in the body. Recent data clearly show that latently infected lymphocytes represent a minimal part of the viral reservoir, while the majority of these cells are macrophages (variably differentiated) scattered in the tissues and lymph nodes. Immunologically-sequestred areas, such as the central nervous system, are particularly relevant in view of the different concentrations of antiviral drugs achieved in the organs. Thus, a careful analysis of the distribution of antiviral drugs, and the assessment of their activity in cells of macrophage lineage, represent key factors in the development of therapeutical strategies aimed to the "cure" of infectious patients.

Dynamics and modulation of human immunodeficiency virus type 1 transcripts in vitro and in vivo

The dynamics of human immunodeficiency virus type 1 (HIV-1) transcription was analyzed in vitro and in vivo by using a specific molecular approach which allows accurate quantitation of the different classes of viral mRNAs. Unspliced (US) and multiply spliced (MS) HIV-1 transcripts were assayed by competitive reverse transcription (cRT)-PCR, using a single competitor RNA bearing in tandem internally deleted sequences of both template species. Acute HIV-1 infection of primary peripheral blood mononuclear cells (PBMCs), monocytes/macrophages cells, and the A3.01 T-lymphocyte-derived cell line was studied; both classes of HIV-1 mRNAs increased exponentially (r2 > 0.98) at days 1 to 3 and 1 to 4 postinfection in HIV(IIIB)-infected A3.01 cells and PBMCs, respectively, whereas monocytes/macrophages infected with monocytotropic HIV(BaL) exhibited a linear (r2 = 0.81 to 0.94) accumulation of US and MS transcripts. Following induction of chronically infected ACH-2 cells, MS transcripts increased 2 h postinduction and peaked at 5 h (doubling time, 58 min), while at 24 h, US mRNAs increased 3,053-fold compared with basal time (doubling time, 137 min). To address the biopathological significance of HIV-1 expression pattern during infection progression, pilot cross-sectional and longitudinal analyses were carried out with samples from untreated and treated HIV-1-infected patients. In almost all untreated (recently infected, long-term nonprogressor, and progressor) patients, MS transcript levels followed the general trend of systemic HIV-1 activity. In patients under treatment with powerful antiretroviral compounds, viral MS transcripts rapidly fell to undetectable levels, indicating that in vivo, levels of MS mRNAs in PBMCs are closely associated with the number of newly infected cells and suggesting a new role for the quantitative analysis of HIV-1 transcription in infected patients.