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A Gessain

Publications and source records attributed to A Gessain.

At least 127 records · Page 7Linked to original sources
PubMed1994

Cross-neutralizing antibodies against cosmopolitan and Melanesian strains of human T cell leukemia/lymphotropic virus type I in sera from inhabitants of Africa and the Solomon Islands.

The so-called cosmopolitan strains of human T cell leukemia/lymphotropic virus type I (HTLV-I) from Japan, Africa, the West Indies, and the Americas differ only slightly (< 3%) in their genomic sequence. On the other hand, the Melanesian strains of HTLV-I are somewhat more divergent, exhibiting only 93% sequence similarity with the cosmopolitan strains. Despite this difference, sera from individuals infected with Melanesian strains cross-react with T cells infected with cosmopolitan strains of HTLV-I, indicating an overall conservation of the B cell immunoprevalent epitopes. Neutralizing antibodies against HTLV-I in sera from virus-infected Africans and Melanesians were assayed by determining their ability to block the formation of syncytia in cocultures of 8166 and T cell lines harboring either cosmopolitan or Melanesian HTLV-I isolates. All six African sera blocked the formation of syncytia with cells infected with HTLV-IC91-PL, a viral isolate from the United States. Similarly, all six Melanesian sera inhibited syncytium formation with cells infected with HTLV-IMEL3, a virus isolate from the Solomon Islands. Although most of these sera inhibited syncytium formation in cell cultures carrying the cosmopolitan as well as the Melanesian HTLV-I strains, neutralizing antibody titers tended to be higher against the homologous virus. All sera failed to inhibit syncytium formation when cells were infected with HTLV-II. These data indicate the involvement of one or more epitopes in syncytial formation, some of which are conserved in all strains of HTLV-I.(ABSTRACT TRUNCATED AT 250 WORDS)

Africa↗
PubMed1994

Phylogenetic classification of human T cell leukaemia/lymphoma virus type I genotypes in five major molecular and geographical subtypes.

Proviral DNA was obtained from ex vivo peripheral blood mononuclear cells of 75 human T cell leukaemia/lymphoma virus type I (HTLV-I)-infected individuals who were either asymptomatic or had adult T cell leukaemia or tropical spastic paraparesis/HTLV-I-associated myelopathy. Amplified long terminal repeats (LTRs) were analysed for restriction fragment length polymorphisms (RFLPs). The results, together with previously published LTR data (a total of 180 specimens analysed), showed the presence of 12 different RFLP profiles with four major molecular subtypes. Furthermore, a fragment of 413 bp (nucleotides 22 to 434) of the U3/R region was sequenced for 12 new HTLV-I specimens originating from Central and West Africa (8 cases), Iran (1 case), Caribbean (2 cases) and Reunion Island (1 case). Phylogenetic analysis using three different techniques (maximum parsimony, neighbour-joining and UPGMA) comparing these 12 strains (including four new African HTLV-I variants) with the 30 published partial HTLV-I LTR sequences (nt 120 to 434) showed the existence of clusters of molecular variants in discrete geographical areas. The topology of the phylogenetic trees is thought to reflect HTLV-I evolution and the migrations of virally infected populations in the recent or distant past. Furthermore, there was a nearly perfect concordance between the clustering based on the LTR sequence homologies and the LTR RFLP subtypes suggesting that this rapid and simple technique is well suited to the investigation of HTLV-I molecular epidemiology. These results allow a new phylogenetic classification of HTLV-I genotypes into five major molecular subtypes: Cosmopolitan (C) subtype widespread all over the world, Japanese (J) subtype, West African (WA) subtype. Central African (CA) subtype and Melanesian (M) subtype.

Africa↗
PubMed1994

Phylogenetic associations of human and simian T-cell leukemia/lymphotropic virus type I strains: evidence for interspecies transmission.

Homologous env sequences from 17 human T-leukemia/lymphotropic virus type I (HTLV-I) strains from throughout the world and from 25 simian T-leukemia/lymphotropic virus type I (STLV-I) strains from 12 simian species in Asia and Africa were analyzed in a phylogenetic context as an approach to resolving the natural history of these related retroviruses. STLV-I exhibited greater overall sequence variation between strains (1 to 18% compared with 0 to 9% for HTLV-I), supporting the simian origin of the modern viruses in all species. Three HTLV-I phylogenetic clusters or clades (cosmopolitan, Zaire, and Melanesia) were resolved with phenetic, parsimony, and likelihood analytical procedures. Seven phylogenetic clusters of STLV-I were resolved with the most primitive (deeply rooted) divergence involving several STLV-I strains from Asian primate species. Combined analysis of HTLV-I and STLV-I revealed that neither STLV-I clusters nor HTLV-I clusters recapitulated host species specificity; rather, multiple clades from the same species were closer to clades from other species than to each other. We interpret these evolutionary associations as support for the occurrence of multiple discrete interspecies transmissions of ancestral viruses between primate species (including human) that led to recognizable phylogenetic clades that persist in modern species. Geographic concordance of divergent host species that harbor closely related viruses reinforces that physical feasibility for hypothesized interspecies virus transmission in the past and in the present.

Amino Acid Sequence↗
PubMed1994

[Adult T-cell leukemia associated with HTLV-1 in a HIV-2 seropositive African].

INTRODUCTION: The aim of this report is to describe an HIV-2 seropositive patient from Mali who had adult-T cell Leukaemia/Lymphoma associated with HTLV-I infection. CASE REPORT: The patient presented with erythroderma and foliate lymphocyte leukaemia. Skin biopsy showed an epidermotropic lymphoma. Tumoural cells expressed a mature T-cell phenotype CD4+/CD25+. High anti-HTLV-I titers and the evidence of monoclonal integration of HTLV-I provirus within circulating lymphoid cells led to the confirmation of HTLV-I as the causal agent in tumour cell transformation. HIV-2 serology was positive. DISCUSSION: Sub-Saharan Africa is a vast reservoir of HTLV-I virus with at least 5 million infected persons. Cases of adult-T cell Leukaemia/Lymphoma in Africans are exceptional. Lack of sufficient knowledge of the disease could partially explain this discrepancy. The main differential diagnosis in dermatology is primary T-cell lymphomas of the skin, particularly mycosis fungoides and Sézary syndrome.

Adult↗
PubMed1994

HTLV-1-like particles and HTLV-1-related DNA sequences in an unambiguous case of Sèzary syndrome.

An unambiguous case of Sèzary syndrome associated with the presence of unusual retroviral infection markers is described. The blood smear showed 15% typical Sèzary cells but also rare atypical lymphocytes with convoluted nuclei, evocative of characteristic adult T-cell leukemia (ATL) flower cells. However, the patient did not present any clinical or biological manifestations of ATL, and human T-cell leukemia virus type 1 (HTLV-1) serology was consistently negative. After being cultured for 4 months, peripheral blood mononuclear cells (PBMC) produced typical type C retrovirus-like particles with budding forms strongly resembling HTLV-1 virions. The producer cells did not express HTLV-1-specific antigens detectable by indirect immunofluorescence (IIF). Southern blotting of uncultured PBMC DNA, submitted to digestion with the restriction enzymes PstI and SacI, and hybridized with a full genomic HTLV-1 probe, showed the presence of specific homologous sequences, absent in all of the healthy donor control PBMC DNAs. These HTLV-1-like sequences presented a restriction enzyme pattern distinct from that of the HTLV-1 prototype genome and of other HTLV-1 proviruses studied up to now. Polymerase chain reaction (PCR) with highly conserved HTLV-1 derived pol and env primers was consistently negative with the patient's DNA. All these results taken together suggest that our patient carries a retroviral agent partially homologous to, but probably different from HTLV-1. The possibility is discussed that this type of retroviral agent might be associated with a subtype of cutaneous T-cell lymphoma (CTCL) represented by a typical Sèzary syndrome with a very low percentage of ATL-like flower cells in the blood smear.

Adult↗
PubMed1993

Abnormal in vitro proliferation and differentiation of T cell colony-forming cells in patients with tropical spastic paraparesis/human T lymphocyte virus type I (HTLV-I)-associated myeloencephalopathy and healthy HTLV-I carriers.

T cell colonies were generated from the peripheral blood mononuclear cells (PBMC) of 10 patients with tropical spastic paraparesis/human T lymphocyte virus type I (HTLV-I)-associated myeloencephalopathy (TSP/HAM), two healthy HTLV-I carriers, and 17 healthy HTLV-I-seronegative subjects. PBMC were cultured in methylcellulose in the absence of added growth factors (spontaneous T cell colonies), or in the presence of phorbol myristate acetate and interleukin 2 (induced T cell colonies). PBMC T cell colony-forming cells (T-CFC) from all TSP/HAM patients and HTLV-I carriers were able to grow in the absence of added growth factors and/or mitogenic stimulation. Pooled spontaneous and induced colonies were composed of cells bearing CD3+, CD4+, CD8+, and CD1+ antigens. Colonies from normal HTLV-I-seronegative subjects displayed mature cells bearing the CD3+, CD4+, CD8+, and CD1- surface phenotype. In addition, spontaneous and induced T cell colonies expressed HTLV-I antigens in 18-38% of the cells from TSP/HAM patients and HTLV-I carriers. These results demonstrate that HTLV-I infection is associated with an abnormal proliferation and differentiation of T cell progenitors in vitro and that the T-CFC from HTLV-I-seropositive individuals are infected, suggesting that T-CFC abnormalities may play a predominant role in the pathophysiology of HTLV-I.

CD3 Complex↗
PubMed1993

Complete nucleotide sequence of a highly divergent human T-cell leukemia (lymphotropic) virus type I (HTLV-I) variant from melanesia: genetic and phylogenetic relationship to HTLV-I strains from other geographical regions.

The high prevalences of antibodies against human T-cell leukemia (lymphotropic) virus type I (HTLV-I) reported for remote populations in Papua New Guinea and the Solomon Islands and for some aboriginal populations in Australia have been verified by virus isolation. Limited genetic analysis of the transmembrane portion (gp21) of the envelope gene of these viruses indicates the existence of highly divergent HTLV-I strains in Melanesia. Here, we report the complete nucleotide sequence of an HTLV-I isolate (designated HTLV-IMEL5) from the Solomon Islands. The overall nucleotide divergence of HTLV-IMEL5 from the prototype HTLV-IATK was approximately 8.5%. The degree of variability in the amino acid sequences of structural genes ranged between 3 and 11% and was higher (8.5 to 25%) for the regulatory (tax and rex) genes and the other genes encoded by the pX region. Since HTLV-IMEL5 was as distantly related to HTLV-II as to the other known HTLV-I strains, it could not have arisen from a reocmbinational event involving HTLV-II but rather might be an example of independent viral evolution in this remote population. These data provide important insights and raise new questions about the origin and global dissemination of HTLV-I.

Amino Acid Sequence↗
PubMed1993

Adult T-cell leukemia/lymphoma revealed by a surgically cured cardiac valve lymphomatous involvement in an Iranian woman: clinical, immunopathological and viromolecular studies.

A 60-year-old woman from the town of Mashhad in northeastern Iran developed cardiac failure due to aortic and mitral regurgitations which needed cardiac valve replacement. Histopathological study of the valves revealed a T-cell non-Hodgkin's lymphoma. Blood examination showed leukemic features with 32% of abnormal white blood cells. Human T-cell leukemia/lymphoma virus type I (HTLV-I) antibodies were present in the serum and the specific env HTLV-I sequences were detected in the DNA extracted from the valves and peripheral blood mononuclear cells (PBMC) using polymerase chain reaction technique. Clonal integration of two HTLV-I copies was found in both the valves and PBMC DNA, thus the diagnosis of adult T-cell leukemia/lymphoma (ATL) was established. In contrast to the acute life-threatening cardiac localization, our case met the diagnostic criteria of chronic ATL, this was confirmed by favorable evolution without chemotherapy during the 24 months after diagnosis. According to our knowledge, this is the first report of an isolated lymphomatous cardiac valve involvement, without other cardiac abnormalities. It seems important to underline that the patient originated from Iran where endemicity of HTLV-I has only recently been discovered.

Aortic Valve↗
PubMed1992

Chronic myelopathy associated with human T-lymphotropic virus type I (HTLV-I).

PURPOSE: To review the clinical, epidemiologic, immunologic, and virologic aspects of the chronic myelopathy associated with human T-cell leukemia/lymphoma virus type I (HTLV-I), currently called tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). DATA IDENTIFICATION: Studies done after 1985, when TSP/HAM was first recognized, were identified by a computer search using MEDLARS II and CANCERLIT. Additional information was acquired from personal files and bibliographies of existing literature. STUDY SELECTION: A total of 400 articles, 90 book chapters, and 150 abstracts from meetings covering all aspects of HTLV-I and neurologic diseases were critically analyzed, and information from 250 publications was included. RESULTS OF DATA ANALYSIS: TSP/HAM is present in most HTLV-I endemic areas, with a prevalence ranging from 5.1 to 128 per 100,000 inhabitants. Up to 20% of patients develop TSP/HAM after transfusion of HTLV-I contaminated blood. Pathologic characteristics indicate a chronic meningomyelitis. The clinical features consist of a chronic progressive spastic paraparesis or paraplegia, sphincter disturbances, and minimal sensory loss. Supraspinal and peripheral nerve involvement is sometimes observed. High titers of HTLV-I-specific antibodies are present in the serum and cerebrospinal fluid. The high level of humoral and cellular immunologic response and the association of TSP/HAM with other immunologic diseases suggest an immune-mediated process. Corticosteroids and immunosuppressor treatment usually result in only short-term improvement. CONCLUSION: TSP/HAM is a common neurologic disease in many parts of the world. All patients with chronic progressive myelopathies should be tested for serum and cerebrospinal fluid HTLV-I-specific antibodies. Systematic screening of blood donors for HTLV-I is necessary to help prevent the dissemination of the virus and the occurrence of post-transfusional cases.

Adolescent↗
PubMed1992

Protein isoforms encoded by the pX region of human T-cell leukemia/lymphotropic virus type I.

The pX region of the human T-cell leukemia/lymphotropic virus type I (HTLV-I) contains at least four open reading frames (orfI-orfIV). orf III and orf IV encode the regulatory HTLV-I proteins Rex and Tax, which together modulate viral expression, and the p21rex protein of unknown function. By using the reverse transcriptase and polymerase chain reaction techniques on the RNA of an HTLV-I-infected cell culture, we uncovered the existence of alternatively spliced mRNAs generated through the use of three splice acceptor sites. These mRNAs encoded protein isoforms derived from the HTLV-I orf I (p12I) and orf II (p13II and p30II). An additional acceptor splice site, used in the processing of the env and tax/rex mRNAs and a singly spliced mRNA for the p21rex protein, was also identified. All of these HTLV-I mRNAs were also detected in freshly isolated cells from HTLV-I-infected individuals. Thus HTLV-I, like the human immunodeficiency virus type 1, has developed fine posttranscriptional mechanisms to increase the complexity of its genome.

Amino Acid Sequence↗
PubMed1992

The cutaneous form of adult T-cell leukemia/lymphoma in a woman from the Ivory Coast. Clinical, immunovirologic studies and a review of the African adult T-cell leukemia/lymphoma cases.

A 36-year-old woman from Ivory Coast, who has lived in France since 1976, had multiple cutaneous nodules and tumors in 1988. Histopathologic studies showed a massive infiltration of the dermis and hypodermis by a diffuse proliferation of mature activated T-cells (CD4-positive, CD25-positive, HLA-DR-positive) with irregular nuclei. The patient did not present with a leukemic picture and only few lymphoid cells with abnormally shaped nuclei were present in the blood. Human T leukemia/lymphoma virus type I (HTLV-I) antibodies were present in the serum and specific HTLV-I pol sequences were detected in the DNA extracted from the tumor nodules and peripheral blood mononuclear cells (PBMC) using the polymerase chain reaction technique. Whereas only a polyclonal integration of HTLV-I provirus was detectable in the PBMC, a clonal integration of three HTLV-I proviruses was demonstrated in the tumor nodules DNA, establishing with certainty the diagnosis of HTLV-I-induced adult T-cell leukemia/lymphoma (ATL). This case illustrates the need for molecular studies to differentiate without ambiguity an ATL from any other type of cutaneous lymphoproliferation, even when it occurs in a HTLV-I-seropositive individual. The situation of HTLV-I-associated ATL in Africa is reviewed.

Adult↗
PubMed1992

Seven years of recurrent severe strongyloidiasis in an HTLV-I-infected man who developed adult T-cell leukaemia.

OBJECTIVE: Human T-cell leukaemia/lymphoma virus type I (HTLV-I) is endemic in Japan, the Caribbean basin and Africa, where it has been aetiologically linked to certain chronic myelopathies and adult T-cell leukamia (ATL). We sought to investigate whether strongyloidiasis, a parasitic disease common in these areas, might be a cofactor in the pathogenesis of ATL, as some reports have suggested. PATIENTS, PARTICIPANTS: One 35-year-old HTLV-I-seropositive French West Indian man with a 7-year history of recurrent strongyloidiasis associated with episodic hyperinfestation presenting at the Centre Hospitalier Intercommunal, Villeneuve St Georges, France. INTERVENTIONS: Treatment with various chemotherapeutic agents and symptomatic therapy for hypercalcaemia and antiviral therapy (zidovudine and interferon). RESULTS: The patient developed ATL and died shortly after, despite chemotherapy. Immunological and virological studies performed during the last 15 months of his life showed an increase of the percentage of peripheral ATL cells, and progression from a polyclonal to a monoclonal integration of HTLV-I proviral DNA in the peripheral blood mononuclear and lymph-node cells. CONCLUSIONS: Recurrent strongyloidiasis appears to have been a possible cofactor associated with progression from healthy carrier state to ATL in our patient.

Adult↗
PubMed1992

Low degree of human T-cell leukemia/lymphoma virus type I genetic drift in vivo as a means of monitoring viral transmission and movement of ancient human populations.

We have studied the genetic variation of human T-cell leukemia/lymphoma virus type I (HTLV-I) isolates in the same individuals over time, as well as of HTLV-I isolates from various parts of the world. The viral DNA fragment studied encodes the carboxy terminus of gp46 and almost all of gp21, both of which are envelope glycoproteins. Samples were obtained from native inhabitants of five African countries, two South American countries, China, the French West Indies, and Haiti and included 14 patients with tropical spastic paraparesis/HTLV-I-associated myelopathy, 10 patients with adult T-cell leukemia, 1 patient with T-cell non-Hodgkin's lymphoma, and 3 healthy HTLV-I-seropositive individuals. DNA analyses of HTLV-I sequences demonstrated that (i) little or no genetic variation occurred in vivo in the same individual or in different hosts from the same region carrying the same virus, regardless of their clinical statuses; (ii) changes in nucleotide sequences in some regions of the HTLV-I genome were diagnostic of the geographical origin of the viruses; (iii) HTLV-I sequences from West African countries (Mauritania and Guinea Bissau) and some from the Ivory Coast and Central African Republic were virtually identical to those from the French West Indies, Haiti, French Guyana, and Peru, strongly suggesting that at least some HTLV-I strains were introduced into the New World through infected individuals during the slave trade events; and (iv) the Zairian HTLV-I isolates represent a separate HTLV-I cluster, in which intrastrain variability was also observed, and are more divergent from the other HTLV-I isolates. Because of the low genetic variability of HTLV-I in vivo, the study of the proviral DNA sequence in selected populations of infected individuals will increase our knowledge of the origin and evolution of HTLV-I and might be useful in anthropological studies.

Base Sequence↗