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Biomedical subjects

G Franchini

Publications and source records attributed to G Franchini.

At least 109 records · Page 6Linked to original sources
PubMed1991

Human T-cell leukemia-lymphoma virus type I (HTLV-I) expression in fresh peripheral blood mononuclear cells from patients with tropical spastic paraparesis/HTLV-I-associated myelopathy.

Tropical spastic paraparesis/human T-cell leukemia-lymphoma virus type I (HTLV-I)-associated myelopathy (TSP/HAM) is a chronic neurological illness epidemiologically associated with HTLV-I infection. We investigated the role of HTLV-I in the pathogenesis of this disease by studying viral expression in fresh uncultured peripheral blood mononuclear cells (PBMCs) of six patients of Caribbean origin with TSP/HAM. The PBMC genomic DNA of all the patients studied carried HTLV-I provirus, but viral expression was not detected by Northern (RNA) blot analysis of total cellular PBMC RNA. When the reverse transcriptase polymerase chain reaction technique was used with primers specific for the tax-rex mRNA, all of the samples were positive for this viral mRNA species, regardless of the duration of the illness (range, 2 to 13 years). The splice junctions for the tax-rex mRNA described in cases of HTLV-I-induced adult T-cell leukemia (position 5183 of the envelope and position 7302 of the pX region) were identical in three TSP/HAM cases studied. To ascertain whether viral expression occurred at a low level in many cells or at a high level in a few permissive cells, we performed in situ hybridization on fresh PBMCs from two patients (2 and 7 years after clinical diagnosis), seeking HTLV-I RNA sequences. Our finding indicated that in vivo HTLV-I expression occurred at a high level in a few cells (1 of every 5,000 PBMCs) in both cases studied. The fact that cells of all six patients with TSP/HAM were positive for viral expression, regardless of the time lag from diagnosis, suggests that persistent expression of a viral product(s) may be pivotal in the pathogenesis of TSP/HAM.

Adult↗
PubMed1991

Dispensable role of the human immunodeficiency virus type 2 Vpx protein in viral replication.

Human immunodeficiency virus type 2 (HIV-2) is similar in genetic organization to HIV-1 but contains a unique gene (vpx) that encodes a 16-kDa protein. A replication-competent molecular clone of HIV-2 (HIV-2sbl/isy) that infects human primary cells in vitro and rhesus monkeys was used to generate three mutations in the vpx gene. In the first mutant, the vpx open reading frame was truncated at amino acid 20; the second mutant was tailored to eliminate the proline-rich carboxyl terminus of the protein; and the third mutant was obtained by addition of four amino acids (KDEL) to the carboxyl terminus of the protein to provide a retention signal in the endoplasmic reticulum. The viral infection kinetics of the three mutant viruses and isogeneic HIV-2sbl/isy in the SupT1 cell line were similar. Slight impairment in the early phases of viral replication was observed during infection of primary human peripheral blood mononuclear cells with the vpx mutant viruses. All of the vpx mutant viruses readily infected macrophages, indicating that vpx expression is dispensable for HIV-2 infection and replication in human macrophages.

Amino Acid Sequence↗
PubMed1991

[Invasive hemodynamic assessment and interventional therapy].

Cardiovascular diseases are the main reason for hospitalization and usually followed by a conservative therapeutic approach. Due to the improvement over the last few years in the results of surgery in the elderly, the number of hemodynamic studies has increased. Hemodynamic studies are generally performed in elderly patients with symptomatic valvular heart disease and acute myocardial infarction with complications. The incidence of complications in the elderly during catheterization and coronarography is higher than in younger but still low. Cardiovascular hemodynamics in the elderly is determined by a combination of lifestyle, the presence of cardiac diseases that increase in prevalence with advancing age (e.g., coronary artery disease) and age-related changes in cardiovascular hemodynamic per se. With age, the tunica media of major blood vessels stiffens. This produces a elevation of systolic blood pressure (afterload) in many elderly patients which in turn increases left ventricular (LV) wall stress and results in mild compensatory LV hypertrophy. This compensatory hypertrophy normalizes wall stress, but produces pertubations in diastolic function such as: a reduction in the rate of both diastolic and LV peak filling, a diminished diastolic compliance associated with LV hypertrophy and a greater dependence upon left atrial contraction to maintain cardiac output. Recently the proportion of these patients who have percutaneous transluminal coronary angioplasty (PTCA) is growing. PTCA can be performed with a high rate of clinical success. Complete revascularization is low, particularly in patients with trivessel disease. The most common reasons for incomplete revascularization were: vessels with chronic total occlusion and vessels with diffuse disease. The rate of major cardiac complications was high among patients at high-risk in the presence of trivessel disease and low left ejection fraction. Long-term results were encouraging. For 90% of patients who had clinical success after PTCA, the end results continued to be beneficial. In conclusion, PTCA is a valid therapeutic alternative in elderly patients with coronary artery disease. In subsets of patients with single and bivessel disease, the short- and long-term outcome is very favourable. In patients with triple vessel disease, early clinical success rate is low but the long-term success rate is, however, acceptable.

Aged↗
PubMed1990

Expanded HIV-1 cellular tropism by phenotypic mixing with murine endogenous retroviruses.

In view of the current interest in in vivo murine models for acquired immunodeficiency syndrome (AIDS), the interaction between human immunodeficiency virus type 1 (HIV-1) and endogenous murine leukemia virus (MuLV)-related retroviruses was investigated with a human leukemic T cell line (PF-382x) that acquired xenotropic MuLV (X-MuLV) after in vivo passage in immunosuppressed mice. Despite similar levels of membrane CD4 expression and HIV-1 125I-labeled gp 120 binding, a dramatic acceleration in the time course of HIV-1 infection was observed in PF-382x compared to its X-MuLV-negative counterpart (PF-382). Moreover, PF-382 cells coinfected by X-MuLV and HIV-1 generated a progeny of phenotypically mixed viral particles, enabling HIV-1 to productively infect a panel of CD4- human cells, including B lymphoid cells and purified normal peripheral blood CD4-/CD8+ T lymphocytes. Mixed viral phenotypes were also produced by human CD4+ T cells coinfected with an amphotropic MuLV-related retrovirus (A-MuLV) and HIV-1. These data show that endogenous MuLV acquired by human cells transplanted into mice can significantly interact with HIV-1, thereby inducing important alterations of HIV-1 biological properties.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Synthesis, oligomerization, and biological activity of the human immunodeficiency virus type 2 envelope glycoprotein expressed by a recombinant vaccinia virus.

The full-length envelope gene from an infectious human immunodeficiency virus type 2 (HIV-2) molecular clone was expressed in CD4+ and CD4- cells by a recombinant vaccinia virus vector. Pulse-chase experiments indicated that gp160 was processed into gp120 and gp41 subunits. Although large amounts of gp120 were shed into the medium, the recombinant vaccinia virus-infected cells fused with uninfected CD4+ cells. The receptor binding of HIV-2 gp120 was further analyzed using a panel composed of nine soluble CD4 mutants containing insertions of 2 amino acids within the first and second immunoglobulin-like domains. Of three mutations previously shown to interfere with HIV-1 gp120 binding, two also interfered with binding of the HIV-2 glycoprotein indicating use of the same binding site. Chemical crosslinking, sucrose gradient sedimentation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis were employed to study the oligomerization of the envelope protein. The data indicated that gp160 assembles posttranslationally into dimers and higher oligomers that are probably tetramers.

Animals↗
PubMed1990

The human immunodeficiency virus type 2 vpr gene is essential for productive infection of human macrophages.

The human immunodeficiency virus (HIV) genetic determinant(s) responsible for tropism in human T cells or macrophages are not well defined. We studied the role of the HIV type 2 (HIV-2) nef and vpr genes in viral tropism. HIV-2 mutants, lacking either vpr or nef genes, or both vpr and nef, were obtained by site-specific mutagenesis of a biologically active HIV-2 proviral clone (HIV-2sbl/isy), which is infectious in both human T cells and macrophages. Viral progeny carrying mutations of nef, vpr, or of both nef and vpr genes replicated more efficiently than the parental virus in primary human peripheral blood cells and in the human Hut 78 T-cell line. In contrast, the HIV-2 nef- mutant infected human macrophages as efficiently as the parental virus, whereas viruses lacking the vpr gene either alone or in conjunction with the lack of the nef gene did not replicate in macrophages. Thus, some lack of nef in HIV-2 enhances viral replication in T cells and does not interfere with viral replication in primary macrophages, whereas vpr is essential for replication of HIV-2 in human macrophages. Because the parental HIV-2sbl/isy cloned virus also infects rhesus macaques, the use in animal studies of these HIV-2 mutants with differences in cell tropism and rates of replication will be highly useful in understanding the mechanism of viral infectivity and possibly pathogenicity in vivo.

Cell Transformation, Viral↗
PubMed1990

Persistent infection of rhesus macaques with a molecular clone of human immunodeficiency virus type 2: evidence of minimal genetic drift and low pathogenetic effects.

In an attempt to generate a suitable animal model to study the infectivity and possible pathogenicity of human immunodeficiency viruses, we intravenously inoculated juvenile rhesus macaques and African green monkeys with a molecularly cloned virus, human immunodeficiency virus type 2 HIV-2sbl/isy, as well as with the uncloned HIV-2nih-z virus. Infection was monitored by virus recovery from the peripheral blood cells and by seroconversion against HIV-2 antigens measured by Western immunoblot, radioimmunoprecipitation, and enzyme-linked immunosorbent assay. We successfully infected two out of two macaques with the molecularly cloned virus and one macaque out of two with the HIV-2nih-z. No evidence of infection was seen in the African green monkeys with either virus. We followed the infected animals for 2 years. The animals remained healthy, although we observed intermittent lymphadenopathy and a transient decrease in the absolute number of circulating CD4+ T lymphocytes in both animals infected with the molecularly cloned virus. Virus isolation from the peripheral blood cells of the infected animals was successful only within the first few months after inoculation. Evidence of persistent infection was provided by the detection of proviral DNA by polymerase chain reaction analysis of the blood cells of the inoculated animals and by the stability of antiviral antibody titers. To evaluate the genetic drift of the proviral DNA, we molecularly cloned viruses which were reisolated 1 and 5 months postinoculation from one of these animals. Comparison of the DNA sequences of the envelope genes of both these isolates indicated that a low degree of variation (0.2%) in the envelope protein had occurred in vivo during the 5-month period. These data suggest that the use of HIV-2sbl/isy in rhesus macaques may represent a good animal model system to study prevention of viral infection. In particular, molecularly cloned virus can be manipulated for functional studies of viral genes in the pathogenesis of acquired immune deficiency syndrome and provides a reproducible source of virus for vaccine studies.

Animals↗
PubMed1989

Identification of the fusion peptide of primate immunodeficiency viruses.

Membrane fusion induced by the envelope glycoproteins of human and simian immunodeficiency viruses (HIV and SIVmac) is a necessary step for the infection of CD4 cells and for the formation of syncytia after infection. Identification of the region in these molecules that mediates the fusion events is important for understanding and possibly interfering with HIV/SIVmac infection and pathogenesis. Amino acid substitutions were made in the 15 NH2-terminal residues of the SIVmac gp32 transmembrane glycoprotein, and the mutants were expressed in recombinant vaccinia viruses, which were then used to infect CD4-expressing T cell lines. Mutations that increased the overall hydrophobicity of the gp32 NH2-terminus increased the ability of the viral envelope to induce syncytia formation, whereas introduction of polar or charged amino acids in the same region abolished the fusogenic function of the viral envelope. Hydrophobicity in the NH2-terminal region of gp32 may therefore be an important correlate of viral virulence in vivo and could perhaps be exploited to generate a more effective animal model for the study of acquired immunodeficiency syndrome.

Amino Acid Sequence↗
PubMed1989

Seroprevalence of HTLV-I in Portugal and evidence of double retrovirus infection of a healthy donor.

The prevalence of antibodies to HTLV-I in 5,475 Portuguese from 6 regions spanning the country was studied. Overall seroprevalence was 0.55%, indicating that Portugal is not an endemic area for this virus. Seropositives were distributed throughout the country, and no geographic clustering was observed. The seroprevalence of individuals who had lived in former Portuguese colonies in Africa (0.7%) was significantly higher than that of individuals who had not been in Africa (0.36%). An increase in seroprevalence with age was noted, and more females than males were antibody-positive, though not significantly so. Serum from one donor (1711), originating from Guinea-Bissau, was shown by Western blot and radioimmune precipitation to react with various proteins of HTLV-I, HIV-1 and -2, and SIV. Based on the serologic profiles and isolation of bona fide HTLV-I from her lymphocytes (confirmed by immunologic analysis, molecular cloning of the provirus and restriction enzyme analysis and sequencing of the DNA), together with the reactivity of her sera with an HIV-2 isolate obtained from her husband, we conclude that this donor was doubly infected with HTLV-I and HIV-2, rather than being the host to an as yet unidentified retrovirus.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Molecular and biological characterization of a replication competent human immunodeficiency type 2 (HIV-2) proviral clone.

We obtained complete genomic clones of human immunodeficiency virus type 2 (HIV-2) from the DNA of the neoplastic human cell line HUT 78 freshly infected with a HIV-2 isolate, strain SBL6669. The recombinant phage DNA was transfected into the lymphocytes of CD4-positive HUT 78 cell line to test the replication competence of the proviral DNA. One genomic clone, designated HIV-2SBL/ISY, yielded retroviral particles after a few weeks of culture of the transfected cells. The HIV-2SBL/ISY clone contained a complete provirus and cellular flanking sequence. We obtained the DNA sequence of the provirus and compared it with the published sequence of two other HIV-2 isolates. The degree of variability among HIV-2 isolates is comparable to that observed among African HIV-1 isolates sequenced to date. Immunologically, HIV-2SBL/ISY is similar to the parental virus (HIV-2SBL6669) but differs in the envelope transmembrane protein that is truncated (gp32-34) in the parental virus and not in HIV-2SBL/ISY (gp41). Both the parental and the cloned viruses are infectious and cytopathic for some human T-cell lines, induce syncytia, and infect a human macrophage cell line (U937) in vitro. The availability of a biologically active HIV-2 clone provides the means to study the role and interaction of HIV-2 genes in vitro as well as to assess the functional similarities among HIV-1 and HIV-2 genes. Since HIV-2SBL/ISY cloned virus infects fresh peripheral blood T cells from Rhesus macaques in vitro and infects the same animal in vivo, its use in animals may represent a model for functional study of viral genes in vivo as well as for development of experimental approaches to prevent and cure retroviral infection in humans.

Blotting, Southern↗
PubMed1988

Molecular epidemiology of HTLV-I-associated non-Hodgkin's lymphomas in Jamaica.

As part of epidemiologic studies of human T-lymphotropic virus (HTLV)-I-associated malignancies in Jamaica, the authors evaluated 26 patients with non-Hodgkin's lymphoma for the presence of integrated HTLV-I provirus in their malignant cells. Fifteen of 26 patients had integrated provirus. All 15 also were HTLV-I antibody positive. Eleven patients did not have integrated provirus, and all 11 were antibody negative. All of the antibody-positive cases had onset of their disease in adulthood (age range, 21-57 years) as opposed to the broad age range of negative cases (4-66 years). Clinical features which were more common in provirus positive than negative patients included leukemic phase, skin involvement, and hypercalcemia, which are all features frequently seen in HTLV-I-associated adult T-cell leukemia/lymphoma (ATLL). The presence of skin involvement, circulating malignant cells, abnormal liver function tests, or the presence of two or more of these four features were statistically significantly different between virus-positive and virus-negative cases. Although the survival of positive cases (6 months) was shorter than that of negative cases (9 months), this was not statistically significant. The only significant determinant of survival was hypercalcemia, with those who developed hypercalcemia at some point in their disease course, independent of their HTLV-I status, surviving a mean of 5 months as compared to a mean of 17.5 months in those who never became hypercalcemic. The six HTLV-I-positive lymphomas that underwent cell typing were all primarily OKT4 positive, whereas two HTLV-I antibody-negative cases that were typed were B-cell lymphomas.

Antibodies, Viral↗
PubMed1988

Envelope sequences of two new United States HIV-1 isolates.

One of the striking molecular aspects of the human T-cell lymphotropic virus type III (HTLV-III) (now called HIV-1) is an unusually large variability in the env genes of different isolates. These differences are clustered primarily within the coding sequences for the large envelope protein and are interspersed among regions within the env gene of relative constancy. Differences among the envelopes of isolates from Africa are so far greater than those among U.S. isolates, but few U.S. isolates have been characterized to date. We report the sequence of the env gene of two U.S. isolates [HTLV-III(MN) and (SC)] and compare them with previously characterized isolates. These two isolates differ substantially from all previously described isolates, especially in the region coding for the large envelope proteins. The env genes of the two new HIV-1 isolates contain conserved and hypervariable regions similar to what has been reported for other isolates, helping to further define those regions. A comparison of the envelope sequences of all the U.S. isolates shows that the similarity between any two ranges from 81 to 85% [except for LAV(BRU) and HTLV-III(BH10) which are 97% similar]. Similar analyses of the African (Zairean) isolates give significantly lower values [71 to 78%, except for 88% between LAV(ELI) and Z6]. This suggests that the African isolates diverged earlier than the U.S. isolates or that transmission of the virus has been more rapid in Africa. Two previous presumptive Haitian isolates are similar to each other and to the U.S. isolates to the same degree as are other U.S. isolates, but differ more markedly from the African isolates suggesting a common lineage of Haitian and U.S. HIV-1 isolates.

Amino Acid Sequence↗
PubMed1988

Genetic variability between isolates of human immunodeficiency virus (HIV) type 2 is comparable to the variability among HIV type 1.

The isolation from macaques of retroviruses related to human immunodeficiency virus (HIV) led to the identification of a second group of human retroviruses (termed HIV-2), which are prevalent in West Africa and closely related to the simian immunodeficiency virus (SIV). We have cloned and determined the complete nucleotide sequence of the human West African retrovirus HIV-2NIH-Z and compared it to that of a previously described strain of HIV-2 (HIV-2ROD) as well as to SIV and HIV-1. We have reached the following conclusions: (i) The HIV-2 isolates are (slightly) more closely related to each other than to SIV, compatible with their isolation from different species. (ii) The variability between HIV-2 isolates is similar in degree and kind to that found among HIV-1 isolates. The equivalent degrees of intragroup divergence suggest that HIV-1 and HIV-2 have existed in their present ranges in Africa for approximately equal lengths of time. The fact that acquired immunodeficiency syndrome is widespread in regions where HIV-1 is prevalent but not in regions where HIV-2 is prevalent suggests a substantial difference in the morbidity rates associated with HIV-1 vs. HIV-2 infection. (iii) HIV-2 and SIV are related to each other more closely than they are to HIV-1.

Amino Acid Sequence↗