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Biomedical subjects

L Butini

Publications and source records attributed to L Butini.

At least 19 recordsLinked to original sources
PubMed1999

Host-specific modulation of the selective constraints driving human immunodeficiency virus type 1 env gene evolution.

To address the evolution of human immunodeficiency virus type 1 (HIV-1) within a single host, we analyzed the HIV-1 C2-V5 env regions of both cell-free genomic-RNA- and proviral-DNA-derived clones. Sequential samples were collected over a period of 3 years from six untreated subjects (three typical progressors [TPs] and three slow progressors [SPs], all with a comparable length of infection except one. The evolutionary analysis of the C2-V5 env sequences performed on 506 molecular clones (253 RNA- and 253 DNA-derived sequences) highlighted a series of differences between TPs and SPs. In particular, (i) clonal sequences from SPs (DNA and RNA) showed lower nucleotide similarity than those from TPs (P = 0. 0001), (ii) DNA clones from SPs showed higher intra- and intersample nucleotide divergence than those from TPs (P < 0.05), (iii) higher host-selective pressure was generally detectable in SPs (DNA and RNA sequences), and (iv) the increase in the genetic distance of DNA and RNA sequences over time was paralleled by an increase in both synonymous (Ks) and nonsynonymous (Ka) substitutions in TPs but only in nonsynonymous substitutions in SPs. Several individual peculiarities of the HIV-1 evolutionary dynamics emerged when the V3, V4, and V5 env regions of both TPs and SPs were evaluated separately. These peculiarities, probably reflecting host-specific features of selective constraints and their continuous modulation, are documented by the dynamics of Ka/Ks ratios of hypervariable env domains.

Base Sequence↗
PubMed1997

Dynamic features of human immunodeficiency virus type 1 (HIV-1) viremia: kinetics of cell-free HIV-1 RNA after therapeutic plasma exchange.

To gain insight into the variables that influence the dynamics of human immunodeficiency virus type 1 (HIV-1) viremia levels, HIV-1 RNA molecules were quantified in plasma from an infected patient undergoing therapeutic plasma exchange (TPEx). After each TPEx procedure (2000 mL of fluid exchanged per session), HIV-1 genome molecule levels dropped to 58%-63% of the basal level but rapidly reverted to pre-TPEx values (doubling time = 3.50-4.04 h). Of interest, mobilization of extravascular cell-free virions (on average, 5.15 x 10(4) viral genome molecules/h) had already occurred during TPEx. After three daily TPEx procedures, HIV-1 viremia rebounded to basal values, while HIV-1 proviruses and viral transcripts in peripheral blood lymphocytes constantly tested at stable levels. Overall, this study extends previous analyses of the rate of HIV-1 turnover, using an alternative approach to the use of antiretroviral drugs, and it provides, albeit indirectly, insights into the amount and dynamic features of extravascular cell-free virus.

Cell-Free System↗
PubMed1997

Changes in CD8 cell subpopulations induced by antiretroviral therapy in human immunodeficiency virus infected patients.

Although CD4+ T cells are the main target of HIV infection, CD8+ cells also play important roles in the interaction between HIV and the host immune system. The aim of this study was to analyze the effect of anti-HIV therapy on the relative proportion of some important CD8+ cell subpopulations. Five HIV-infected patients were enrolled, and blood samples were collected several times, within 90 days from the initiation of therapy. CD4+ cell count and HIV viremia were investigated, as well as the expression of CD38, HLA-DR, CD28, CD57, CD30, CD95 molecules on CD8+ cells. A complex remodeling of CD8+ cell subpopulations took place between week 2 and week 7 of treatment. This remodeling mainly consisted of: i) decrease of CD8+CD38+ and CD8+DR+ cells; ii) increase of CD8+CD28+ cells; and iii) decreased expression of the CD95/Fas molecule on CD8+ cells. Overall, these findings suggest that effective anti-HIV therapy induces changes of CD8+ subpopulations showing the reversal of the state of chronic activation that is caused by viral replication.

Adult↗
PubMed1996

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.

Cell Line↗
PubMed1995

Cervical dysplasia in HIV-seropositive women: role of human papillomavirus infection and immune status.

OBJECTIVE: In the present study we investigated the cytologic and colposcopic characteristics of a cohort of HIV-infected women, with the aim to determine a relationship between immunologic status and frequency and/or severity of cervical abnormalities. MATERIALS AND METHODS: 21 women, who tested positive for the HIV antibody and who were admitted as outpatients because of various gynecologic complications or because of an HIV infection that was under regular clinical surveillance. A pelvic examination was performed and Papanicolaou smears were obtained from endocervix and ectocervix before colposcopic examination. Cytologic samples for human papillomavirus (HPV) detection by polymerase chain reaction were also collected. Results obtained in the group of HIV-infected women were compared with findings in a group of 473 seronegative women recruited consecutively from our outpatient population. Serum samples for T lymphocytes were drawn within 2 weeks of cytologic and colposcopic examination. CD4 and CD8 monoclonal antibodies were purchased from Becton Dickinson (Mountain View, Calif., USA). RESULTS: HIV-infected women had a significantly higher percentage of HPV DNA positivity with respect to the outpatient population (67 vs. 7%, respectively, p < 0.001). Analysis of cytologic specimens revealed 9 women (43%) with cytologic evidence of cervical dysplasia in the HIV-seropositive group vs. 23 (5%) of 473 in the outpatient population (p < 0.001). All the HIV-seropositive women with cervical dysplasia presented an associated HPV DNA positivity; in particular, the percentage of associated HPV DNA type 16 in cervical dysplasia was 78% (7/9 cases). In HIV-infected women, the evaluation of T lymphocyte subset distribution suggested a significant relationship between CD4+ cell decrease and severity of cytologic findings (p = 0.03). DISCUSSION: The HIV-infected women had a tenfold higher prevalence of both HPV infection and cervical dysplasia than the outpatient population; this increased risk seems to be limited mainly to those who also had genital HPV infection. The analysis of immunologic status confirmed previous observations that an impaired immune system results in increased cervical disease.

Adult↗
PubMed1994

Intercellular adhesion molecules (ICAM)-1 ICAM-2 and ICAM-3 function as counter-receptors for lymphocyte function-associated molecule 1 in human immunodeficiency virus-mediated syncytia formation.

It has been previously demonstrated that lymphocyte function-associated molecule 1 (LFA-1) plays a major role in human immunodeficiency virus (HIV)-mediated syncytia formation. In the present study we investigated the involvement of intercellular adhesion molecule-1 (ICAM-1), ICAM-2 and ICAM-3 in the process. The ability of monoclonal antibodies (mAb) directed against ICAM-1, ICAM-2 and ICAM-3 to block syncytia was analyzed either in phytohemagglutinin (PHA)-activated lymphocytes infected in vitro with primary or laboratory strains of HIV or by coculturing a T cell line stably expressing HIV envelope with PHA-activated lymphocytes. Complete inhibition of syncytia formation was observed only by the simultaneous addition to the cell cultures of all (i.e. anti-ICAM-1, anti-ICAM-2 and anti-ICAM-3) mAb. These results indicate that the interaction between LFA-1 and ICAM is a critical step in HIV-mediated syncytia formation, and that ICAM-1, ICAM-2 and ICAM-3 are the receptor molecules for the LFA-1-dependent syncytia formation.

Antibodies, Monoclonal↗
PubMed1993

Kinetics of human immunodeficiency virus type 1 (HIV-1) DNA and RNA synthesis during primary HIV-1 infection.

HIV-1 replication and viral burden in peripheral blood mononuclear cells (PBMC) have been reported to be high in primary infection but generally very low during the prolonged period of clinical latency. It is uncertain precisely when this transition occurs during the HIV-1 infection and what the relationship is between the changes in HIV-1 replication versus the clearance of infected cells in the overall control of viral replication. In the present study, the kinetics of viral burden (i.e., frequency of HIV-1-infected cells) and replication during primary and early-chronic infection were analyzed in PBMC of four acutely infected individuals. High frequencies of HIV-1-infected cells and high levels of virus replication were observed in PBMC after primary HIV-1 infection. Down-regulation of virus replication in PBMC was observed in all four patients coincident with the emergence of HIV-1-specific immune responses. Other parameters of virus replication, such as circulating plasma p24 antigen and plasma viremia showed similar kinetics. In contrast, a significant decline in viral burden in PBMC was observed in only one of four patients. These results indicate that the down-regulation in the levels of virus replication associated with the clinical transition from acute to chronic infection does not necessarily reflect a reduction in viral burden, thus suggesting the involvement of additional factors. Identification of these factors will be important in elucidating the host mechanisms involved in the early control of HIV-1 infection and disease.

Base Sequence↗
PubMed1993

HIV infection is active and progressive in lymphoid tissue during the clinically latent stage of disease.

Primary infection with the human immunodeficiency virus (HIV) is generally followed by a burst of viraemia with or without clinical symptoms. This in turn is followed by a prolonged period of clinical latency. During this period there is little, if any, detectable viraemia, the numbers of infected cells in the blood are very low, and it is extremely difficult to demonstrate virus expression in these cells. We have analysed viral burden and levels of virus replication simultaneously in the blood and lymphoid organs of the same individuals at various stages of HIV disease. Here we report that in early-stage disease there is a dichotomy between the levels of viral burden and virus replication in peripheral blood versus lymphoid organs. HIV disease is active in the lymphoid tissue throughout the period of clinical latency, even at times when minimal viral activity is demonstrated in blood.

Acquired Immunodeficiency Syndrome↗
PubMed1993

HIV-1 infection in the lymphoid organs.

AIM: To develop a model of HIV disease progression. METHOD: Comparative analysis of viral burden and replication between peripheral blood and lymphoid organs and of the changes in viral distribution in the lymphoid tissue. RESULTS: In early-stage disease HIV-1-infected cells were sequestered in the lymphoid tissue, and the viral particles were concentrated and trapped in the germinal centers. The dichotomy in viral burden and viral replication between peripheral blood and lymphoid tissue was related to the histopathologic abnormalities associated with different stages of disease. CONCLUSIONS: These histopathologic abnormalities may not only explain the changes in viral distribution observed in the lymphoid tissue in different stages of the disease, but may also reflect different functional states of the immune system during the progression of HIV-1 infection from early- to late-stage disease.

DNA, Viral↗
PubMed1993

The RRE of human immunodeficiency virus type 1 contributes to cell-type-specific viral tropism.

As part of a general program investigating the mechanism of the Rev axis of human immunodeficiency virus type 1 (HIV-1) autoregulation, a series of proviral HIV-1 mutants which differ from the parental HXB2 strain at selected positions within the RRE were constructed. All of the mutations were designed to perturb the RRE by introducing local helix disruptions without altering the coding potential of the overlapping envelope open reading frame. Viral replication in various cell types was monitored by a cell supernatant reverse transcriptase assay and Northern (RNA blot) analysis. All proviral RRE mutants displayed at least some impairment in replication. However, the relative impairment varied drastically among the various cell types tested. This suggests that the RRE may contribute to cell-type-specific viral tropism.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Extensive sequence-specific information throughout the CAR/RRE, the target sequence of the human immunodeficiency virus type 1 Rev protein.

The significance and location of sequence-specific information in the CAR/RRE, the target sequence for the Rev protein of the human immunodeficiency virus type 1 (HIV-1), have been controversial. We present here a comprehensive experimental and computational approach combining mutational analysis, phylogenetic comparison, and thermodynamic structure calculations with a systematic strategy for distinguishing sequence-specific information from secondary structural information. A target sequence analog was designed to have a secondary structure identical to that of the wild type but a sequence that differs from that of the wild type at every position. This analog was inactive. By exchanging fragments between the wild-type sequence and the inactive analog, we were able to detect an unexpectedly extensive distribution of sequence specificity throughout the CAR/RRE. The analysis enabled us to identify a critically important sequence-specific region, region IIb in the Rev-binding domain, strongly supports a proposed base-pairing interaction in this location, and places forceful constraints on mechanisms of Rev action. The generalized approach presented can be applied to other systems.

Base Sequence↗
PubMed1991

Lymphoid organs function as major reservoirs for human immunodeficiency virus.

The total number of human immunodeficiency virus type 1 (HIV-1)-infected circulating CD4+ T lymphocytes is considered to be a reflection of the HIV burden at any given time during the course of HIV infection. However, the low frequency of HIV-infected circulating CD4+ T lymphocytes and the low level or absence of plasma viremia in the early stages of infection do not correlate with the progressive immune dysfunction characteristic of HIV infection. In this study, we have determined whether HIV-infected circulating CD4+ T lymphocytes are a correct reflection of the total pool of HIV-infected CD4+ T cells (i.e., HIV burden). To this end, HIV burden has been comparatively analyzed in peripheral blood and lymphoid tissues (lymph nodes, adenoids, and tonsils) from the same patients. The presence of HIV-1 DNA in mononuclear cells isolated simultaneously from peripheral blood and lymphoid tissues of the same patients was determined by polymerase chain reaction amplification. We found that the frequency of HIV-1-infected cells in unfractionated or sorted CD4+ cell populations isolated from lymphoid tissues was significantly higher (0.5-1 log10 unit) than the frequency in peripheral blood. Comparable results were obtained in five HIV seropositive patients in the early stages of disease and in one patient with AIDS. These results demonstrate that a heavy viral load does reside in the lymphoid organs, indicating that they may function as major reservoirs for HIV. In addition, the finding of a heavy viral load in the lymphoid organs of patients in the early stages of disease may explain the progressive depletion of CD4+ T lymphocytes and the immune dysfunction associated with the early stages of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Human immunodeficiency virus (HIV) infection in CD4+ T lymphocytes genetically deficient in LFA-1: LFA-1 is required for HIV-mediated cell fusion but not for viral transmission.

In the present study, we demonstrated that expression of the LFA-1 molecule is necessary for cell fusion and syncytia formation in human immunodeficiency virus (HIV)-infected CD4+ T lymphocytes. In contrast, the lack of expression of LFA-1 does not influence significantly cell-to-cell transmission of HIV. In fact, LFA-1- T lymphocytes obtained from a leukocyte adhesion deficiency patient were unable to fuse and form syncytia when infected with HIV-1 or HIV-2, despite the fact that efficiency of HIV infection (i.e., virus entry, HIV spreading, and levels of virus replication) was comparable with that observed in LFA-1+ T lymphocytes. In addition, we provide evidence that LFA-1 by mediating cell fusion contributes to the depletion of HIV-infected CD4+ T lymphocytes in vitro.

Antibodies, Monoclonal↗
PubMed1991

Dissociation between syncytia formation and HIV spreading. Suppression of syncytia formation does not necessarily reflect inhibition of HIV infection.

In this study, we have observed that a dissociation may occur in vitro between syncytia formation and HIV spreading. Efficient HIV spreading and virus replication occurred either in HIV-infected LFA-1+ lymphocytes treated with anti-LFA-1 mAb or in HIV-infected lymphocytes genetically deficient in LFA-1, despite the fact that syncytia formation was completely suppressed. Therefore, these results indicate that syncytia formation cannot be used as the sole parameter to evaluate the spread of HIV in vitro.

Antibodies, Monoclonal↗
PubMed1990

CD8+ T lymphocytes of patients with AIDS maintain normal broad cytolytic function despite the loss of human immunodeficiency virus-specific cytotoxicity.

In this study, we have investigated the potential mechanisms responsible for the loss of human immunodeficiency virus type 1 (HIV-1)-specific cytolytic activity in the advanced stages of HIV-1 infection. We have demonstrated that HIV-1-specific cytotoxic T lymphocytes are predominantly contained within the CD8+DR+ subset. Furthermore, we have shown by a redirected killing assay that there is a dichotomy between HIV-1-specific cytolytic activity and broad cytolytic potential since the cytolytic machinery of CD8+DR+ cells is still functioning even in patients with AIDS who have lost their HIV-1-specific cytolytic activity. In addition, by comparative analysis of these two types of cytolytic activity over time we have demonstrated a progressive loss of HIV-1-specific cytolytic activity in the advanced stages of the disease, whereas the cytolytic potential remained unchanged regardless of the clinical stage. As previously shown in patients with AIDS, even in asymptomatic HIV-1-seropositive patients, CD8+DR+ cells from the same patient, compared to CD8+DR- lymphocytes, showed a substantial reduction in their ability to proliferate in vitro in response to different stimuli, such as mitogens (phytohemagglutinin and phorbol 12-myristate 13-acetate) and monoclonal antibodies directed against CD3, CD2, and CD28 molecules, and displayed a defective clonogenic potential. Thus, on the basis of these results we propose that the loss of HIV-1-specific cytolytic activity in HIV-1-infected individuals may result at least in part from a progressive decrease in the pool of HIV-1-specific cytotoxic T lymphocytes belonging to the CD8+DR+ subset whose ability to expand has been impaired.

Acquired Immunodeficiency Syndrome↗