Expression and immunogenicity in rats of recombinant adenovirus 5 DNA plasmids and vaccinia virus containing the HTLV-I env gene

The complete human T-cell leukemia virus type I (HTLV-I) env gene was inserted into an expression cassette containing the adenovirus 5 major late promoter (Ad5-MLP). Recombinant Ad5-HTLV-I-env was obtained by homologous recombination in 293 cells simultaneously transfected by the expression cassette and the genomic DNA of Ad5. In vitro expression of the HTLV-I-env gene in the recombinant vector was detected by immunofluorescence and Western blotting. Functional expression of HTLV-I-env was confirmed by syncitium formation specifically in HeLa cells infected with Ad5-HTLV-I-env. Two immunization regimens against HTLV-I were tested in WKY and Fischer F-344 rats. The first involved WKY rats primed with Ad5-HTLV-I-env or naked DNA plasmids containing the HTLV-I-env gene and boosted with Ad5 containing the HTLV-I-env gp46 gene or with baculovirus-derived recombinant gp46. No antibody against HTLV-I was detected, while HTLV-I-specific cytotoxic T lymphocytes were recovered from all immunized groups but not from controls. The second approach involved Fischer F-344 rats primed and boosted with recombinant vaccinia virus containing the HTLV-I-env gene. Such rats developed antibodies against the HTLV-I env gp21 and gp46 (non-neutralizing). After challenge with human HTLV-I-producing cells (MT-2), both immunization regimens were found to induce partial protection.

Human herpes virus 8 (Kaposi's sarcoma herpes virus) and malignant lymphoproliferations in France: a molecular study of 250 cases including two AIDS-associated body cavity based lymphomas

The new human herpes virus 8 (HHV8) was recently detected in cases of body cavity based lymphoma (BCBL), a rare B cell lymphoma, mostly AIDS-associated. We investigated for HHV8 DNA sequences a series of 250 B or T cell lymphoproliferative malignancies, as seen in France, including 126 leukemias and 124 lymphomas (232 non-AIDS-associated and 18 AIDS-associated tumors). HHV8 sequences were detected in only three patients. The first two were homosexual males, HIV-infected since 1985 who suffered from a BCBL initially characterized in one case by a pleural lymphomatous effusion and a peritoneal one in the other case. A high level of HHV8 copies was detected in the tumoral cells of these two BCBL. In contrast, in the third positive patient who had an AIDS-associated immunoblastic lymphoma, the HHV8 sequences level was quite low. In the two BCBL patients, the HHV8-infected clonal B cells had a large immunoblastic feature with an indeterminate phenotype and were also infected by Epstein-Barr virus. In one BCBL case, a semiquantitative PCR analysis revealed that the HHV8 sequences were much more abundant in the effusion tumor cells than in the cutaneous Kaposi's biopsy while no HHV8 sequence was detectable in the peripheral blood lymphocytes. This study reports HHV8-associated BCBL in European AIDS patients and confirms that HHV8 is present at a high copy number in the tumoral B cells of this malignancy. Furthermore, HHV8 does not seem to play a pathogenic role in any of the other T or B malignant lymphoid neoplasias studied so far. This study also stresses the necessity for quantification studies in interpretation of a positive PCR analysis for HHV8 sequences, especially in patients at risk for HIV infection or Kaposi's sarcoma.

Evidence in Gabon for an intrafamilial clustering with mother-to-child and sexual transmission of a new molecular variant of human T-lymphotropic virus type-II subtype B

Following the observation of an HTLV-II seropositive 60-year-old woman living in Gabon (Central Africa), a serologic and molecular study of her family members was conducted in an attempt to determine the duration of the HTLV-II infection and the modes of transmission of the virus. Among 41 family members, five were HTLV-I seropositive and 7 exhibited specific HTLV-II antibodies in their sera as demonstrated by high immunofluorescence titers on C19 cells and/or specific Western-blot pattern. The second husband of the index case and two of his sisters were infected by the virus, suggesting the presence of HTLV-II in this family over two generations. Sequence analysis of an amplified fragment of 172 nucleotides within the gp21 of the env region (6469-6640) of four HTLV-II infected individuals revealed a new HTLV-II molecular variant of the subtype b diverging from the prototypes NRA and G12 by seven (4.1%) and five (2.9%) bases substitutions, respectively. Molecular analysis of the total env gene (1462 bp) and fragments of the pol and pX regions confirmed that this new African variant was the most divergent HTLV-II subtype b yet described, exhibiting 2.3% of nucleotide substitutions in the env gene (33 bases) as compared to the two HTLV-II b prototypes. These data demonstrate, for the first time in Africa, intrafamilial both mother-to-child transmission and sexual transmission between spouses of an HTLV-II b molecular variant, and also suggest that this virus has been present in Gabon for a long period of time.

An HTLV-I/II vaccine: from animal models to clinical trials?

A human T-lymphotropic virus type I/II (HTLV-I/II) vaccine is necessary in view of two etiologically related, life-threatening diseases, namely, adult T-cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-I-associated myelopathy. When the risk of developing autoimmune diseases such as uveitis, polymyositis, and arthritis is included, one can estimate the life-long risk of infected individuals to develop an HTLV associated pathology as approximately 10%. The populations at risk are, in a large majority, from developing countries but the epidemic of HTLV-II infection in intravenous drug users (IVDU) represents a possible reservoir for dissemination in the general population. The number of HTLV-I-infected individuals (15 to 25 million), together with the severity of associated disease, justifies the development of a vaccine. Different vaccine preparations have been developed, using mostly recombinant pox and adenoviruses, but DNA plasmid technology will soon become a feasible approach. Various animal models exist for experimental viral infections, involving rats, rabbits, or monkeys, but up to now, neither hematological nor neurological disorders have been induced by HTLV infection in such animal models. For long-term protection from HTLV-I-associated diseases, vaccination should induce both neutralizing antibodies and specific cell-mediated immunity. This will require the incorporation of both env and gag coding sequences in the vaccine preparations. Preventive clinical trials may involve different cohorts of seronegative young girls from endemic areas prior to sexual activity and IVDU in the industrialized world. In parallel, one should consider therapeutic vaccine trials in HTLV-I-positive mothers and IVDU to protect them against disease development. The observed rate of seroconversion in these different cohorts makes such trials feasible.

Genetic variability and molecular epidemiology of human and simian T cell leukemia/lymphoma virus type I

In the past few years, numerous investigators have demonstrated that human T cell leukemia/lymphoma virus type I (HTLV-I) possesses a great genetic stability, and recent data indicate that viral amplification via clonal expansion of infected cells, rather than by reverse transcription, could explain this remarkable genetic stability. In parallel, the molecular epidemiology of HTLV-I proviruses showed that the few nucleotide changes observed between isolates were specific for the geographical origin of the patients but not for the type of the associated pathologies (adult T cell leukemia/lymphoma, tropical spastic paraparesis/HTLV-I-associated myelopathy). Thus, based on sequence and/or restriction fragment length polymorphism analysis of more than 250 HTLV-I isolates originating from the main viral endemic areas, three major molecular geographical subtypes (or genotypes) emerged, strongly supported by phylogenetic analysis (high bootstrap values). Each of these genotypes (Cosmopolitan, Central African, and Melanesian) appeared to arise from ancient interspecies transmission between monkeys infected with simian T cell leukemia/lymphoma virus type I and humans. Furthermore, careful sequences analyses indicate that, within (or alongside) these three main genotypes, there are molecular subgroups defined clearly by several specific mutations but not always supported by phylogenetic analyses. Thus in Japan, there is evidence for two ancestral HTLV-I lineages: the classical Cosmopolitan genotype, representing approximately 25% of the HTLV-I present in Japan and clustering in the southern islands; and a related subgroup that we called the Japanese group. Similarly, within the Central African cluster, there are molecular subgroups defined by specific substitutions in either the env or the long terminal repeat. Furthermore, recent data from our laboratory indicate the presence of a new molecular phylogenetic group (fourth genotype) found among inhabitants of Central Africa, particularly in Pygmies. While geographical subtypes vary from 2 to 8% between themselves, HTLV-I quasi-species present within an individual appear to be much lower, with a variability of < 0.5%.

What is the situation of human T cell lymphotropic virus type II (HTLV-II) in Africa? Origin and dissemination of genomic subtypes

Human T cell lymphotropic virus type II (HTLV-II) and its two genomic subtypes, A and B, which differ by 3 to 6% at the nucleotide level (depending on the gene studied), were until recently considered to be endemic only in certain Indian tribes in the Americas and were therefore considered mainly as a "New World virus." First, the evidence of HTLV-II antibodies and later characterization of isolates from sex workers or individuals living in large West and Central African cities suggested that HTLV-II subtype A could have been imported recently in Africa. However, the findings of HTLV-II infection in two Pygmy populations living in remote areas of Zaire and Cameroon suggest that HTLV-II might have been in Africa for a very long time. Furthermore, the discovery of HTLV-II subtype B virus in some of these Pygmies, but also in other individuals from Zaire and within a family in Gabon for three generations, confirms the hypothesis of a very ancient presence of this HTLV-II subtype B on the African continent Recent data indicate also that there exist in Central Africa specific HTLV-II divergent strains including an HTLV-II B variant strain in Gabon. In the context of recent evidence for interspecies transmission in Central and West Africa of HTLV-I/simian T cell lymphotropic virus type I (STLV-I) strains, leading to the two major HTLV-I African subtypes, we would like to suggest that some STLV-II (closely related to HTLV-II subtype B) still exist or might have existed in Central/East Africa. The recent finding of quite divergent primate T cell lymphotropic viruses (PTLVs) in several Pygmy chimpanzees of Zairian origin (PTLV-PP1664 and STLV-PP) and in wild-caught baboons in Eritrea, Ethiopia (PTLV-L), also supports the complementary hypothesis of a yet to be discovered new HTLV-II-related virus in humans. Careful study of the indeterminate Western blot patterns present in some populations in Central Africa strongly suggests that such an exciting possibility exists, thus opening new avenues of research on both the history of primate retroviruses and that of early human groups.

Lack of evidence of HTLV-I/II infection in T CD8 malignant or reactive lymphoproliferative disorders in France: a serological and/or molecular study of 169 cases

Human T lymphotropic virus type II (HTLV-II), originally isolated in 1982 from a patient with a "T hairy cell leukemia", has not yet been proven to be the causative agent of any specific hematological disease. In order to screen for such an event, and because HTLV-II has a preferential tropism for OKT8 (CD8) T cells (both in vivo and in vitro), we searched for the presence of HTLV-II in lymphoproliferative diseases (LP) of CD8+ T cells. We report a serological and/or molecular study of 169 patients with a T CD8 LP, including 76 patients with malignant or reactive T CD8 LP (34 lymphomas, 27 large granular leukemias, three prolymphocytic leukemias, one hairy cell leukemia, 11 reactive T CD8 LP) and 93 HIV-1+ patients with a T CD8 peripheral lymphocytosis ( > 1500/mm3) from a prospective HIV cohort involving 1264 individuals. In the first series, the 40 sera available were all HTLV-I/II negative, except a 67-year-old French Guyanan man, with a cutaneous large T CD8 cell lymphoma, HTLV-I+. Furthermore, the molecular analysis of the 69 available DNA samples by PCR failed to detect any proviral HTLV-I/II sequences, except for the HTLV-I+ patient. The serological study of the 93 HIV-1+ individuals with CD8 lymphocytosis, showed that three patients were HTLV-I+, but none was HTLV-II+. Thus, in contrast to HTLV-I, whose etiological role in adult T cell leukemia is now well established, there is neither epidemiological nor molecular evidence that prototypic HTLV-II may be etiologically associated specifically with any of the CD8+ T cell LP investigated in this report.

HCV infection in a rural population of the Central African Republic (CAR): evidence for three additional subtypes of genotype 4

The prevalence of hepatitis C virus (HCV) antibodies, HCV infection, and genotypes was studied in a rural population of the Central African Republic. In five villages, blood samples were taken from all the inhabitants present during the survey, belonging to Pygmies (299) and to Bantu and Banda ethnic groups (247). Using a second-generation ELISA screening and confirmation by immunoblot assay for the detection of HCV antibodies, all the Pygmies were negative, whereas seven Bantus/Bandas, aged > 35 years and with no familial relationship, were positive, giving a prevalence of 2.8% in this ethnic group. Five samples were also PCR positive; all belonged to genotype 4, but with three new subtypes identified by phylogenic analysis. These results indicate the co-existence of different HCV subtypes and raise questions about the natural transmission of HCV in this secluded population.

Isolation and characterization of a new simian T-cell leukemia virus type 1 from naturally infected celebes macaques (Macaca tonkeana): complete nucleotide sequence and phylogenetic relationship with the Australo-Melanesian human T-cell leukemia virus type 1

A study of simian T-cell leukemia virus type 1 (STLV-1) infection in a captive colony of 23 Macaca tonkeana macaques indicated that 17 animals had high human T-cell leukemia virus type 1 (HTLV-1) antibody titers. Genealogical analysis suggested mainly a mother-to-offspring transmission of this STLV-1. Three long-term T-cell lines, established from peripheral blood mononuclear cell cultures from three STLV-1-seropositive monkeys, produced HTLV-1 Gag and Env antigens and retroviral particles. The first complete nucleotide sequence of an STLV-1 (9,025 bp), obtained for one of these isolates, indicated an overall genetic organization similar to that of HTLV-1 but with a nucleotide variability for the structural genes ranging from 7.8 to 13.1% compared with the HTLV-1 ATK and STLV-1 PTM3 Asian prototypes. The Tax and Rex regulatory proteins were well conserved, while the pX region, known to encode new proteins in HTLV-1 (open reading frames I and II), was more divergent than that in the ATK strain. Furthermore, a fragment of 522 bp of the gp21 env gene from uncultured peripheral blood mononuclear cell DNAs from five of the STLV-1-infected monkeys was sequenced. Phylogenetic trees constructed with the long terminal repeat and env (gp46 and gp21) regions demonstrated that this new STLV-1 occupies a unique position within the Asian STLV-1 and HTLV-1 isolates, being, by most analyses, related more to the Australo-Melanesian HTLV-1 topotype than to any other Asian STLV-1. These data raise new hypotheses on the possible interspecies viral transmission between monkeys carrying STLV-1 and early Australoid settlers, ancestors of the present day Australo-Melanesian inhabitants, during their migrations from the Southeast Asian land mass to the greater Australian continent.

Characterization of macromolecular lignins as Epstein-Barr virus inducer in foodstuff associated with nasopharyngeal carcinoma risk

Epstein-Barr virus (EBV)-inducing activity was previously demonstrated to occur in various foodstuffs, including dried salted fish in southern China and 'harissa', a homemade spice mixture in Tunisia, whose consumption is epidemiologically associated with an increased risk for developing nasopharyngeal carcinoma (NPC). For the isolation and the characterization of active ingredients in harissa, we used as a rapid screening assay the induction of the chloramphenicol acetyltransferase (CAT) activity through the EBV-DR promoter in DR-CAT Raji cells. After fractionation of harissa and column chromatography on Sepharose-CL4B, the major inducing activity was associated with a macromolecular fraction which was chemically characterized as liginin-containing complexes. The active material enhanced EBV-DR induction with an activity comparable to the tumor promoter and strong EBV inducer, 12-O-tetradecanoylphorbol-13-acetate. Experiments with inhibitors of protein kinase C-related pathways suggested that the EBV-inducing activity of lignin fractions operates through a different pathway. Our results on the presence of specific lignin fractions in high-risk food items that can induce important cellular functions linked to tumor promotion are discussed in relation to NPC genesis and etiology.

Isolation and molecular characterization of a human T-cell lymphotropic virus type II (HTLV-II), subtype B, from a healthy Pygmy living in a remote area of Cameroon: an ancient origin for HTLV-II in Africa

We report characterization of a human T-cell lymphotropic virus type II (HTLV-II) isolated from an interleukin 2-dependent CD8 T-cell line derived from peripheral blood mononuclear cells of a healthy, HTLV-II-seropositive female Bakola Pygmy, aged 59, living in a remote equatorial forest area in south Cameroon. This HTLLV-II isolate, designated PYGCAM-1, reacted in an indirect immunofluorescence assay with HTLV-II and HTLV-I polyclonal antibodies and with an HTLV-I/II gp46 monoclonal antibody but not with HTLV-I gag p19 or p24 monoclonal antibodies. The cell line produced HTLV-I/II p24 core antigen and retroviral particles. The entire env gene (1462 bp) and most of the long terminal repeat (715 bp) of the PYGCAM-1 provirus were amplified by the polymerase chain reaction using HTLV-II-specific primers. Comparison with the long terminal repeat and envelope sequences of prototype HTLV-II strains indicated that PYGCAM-1 belongs to the subtype B group, as it has only 0.5-2% nucleotide divergence from HTLV-II B strains. The finding of antibodies to HTLV-II in sera taken from the father of the woman in 1984 and from three unrelated members of the same population strongly suggests that PYGCAM-1 is a genuine HTLV-II that has been present in this isolated population for a long time. The low genetic divergence of this African isolate from American isolates raises questions about the genetic variability over time and the origin and dissemination of HTLV-II, hitherto considered to be predominantly a New World virus.

Risk factors for maternal HTLV-I infection in French Guiana: high HTLV-I prevalence in the Noir Marron population

The aim of this study was to compare rates of human T-cell lymphotropic virus type I (HTLV-I) seroprevalence in pregnant women belonging to different ethnic groups in French Guiana and to determine the risk factors associated with HTLV-I seropositivity. All 1,873 deliveries between 1 July 1991 and 30 June 1993 in the only gynecologic and obstetric unit at Saint Laurent du Maroni were enrolled. Serologic status could be established for 1,727 women, with 75 (4.3%) being HTLV-I seropositive. The HTLV-I seroprevalence rate differed significantly between ethnic groups: 5.7% for Noir-Marron (70/1,302), 6.3% for Haitian (3/50), and 0% for Creole (126), Amerindians (166), and Hmong (64). In Noir-Marron pregnant women, HTLV-I seropositivity was associated with a maternal age of > 35 years [odds ratio (OR), 3.3; 95% confidence interval (CI), 1.4-7.6], prior miscarriage (OR, 1.7; CI, 1-2.8), prior cesarean section (OR, 2.1; CI, 1.1-4.0), a parity > 4 (OR, 4.0; CI, 1.8-8.8), a gravidity > 6 (OR, 4.2; CI, 2.0-7.2), and a negative Rhesus factor (OR, 2.2; CI, 1.1-4.5). Two separate stepwise logistic regressions were done because gravidity and parity were highly correlated. HTLV-I seropositivity remained associated with a gravidity > 6 (OR, 3.9; CI, 2.1-7.4) and a negative Rhesus factor (OR, 2.6; CI, 1.2-5.3) for the first model and with a parity > 4 (OR, 4.1; CI, 1.9-9.0) and a negative Rhesus factor (OR, 2.5; CI, 1.2-5.1) for the second model.(ABSTRACT TRUNCATED AT 250 WORDS)

HTLV-I/II infection in a high viral endemic area of Zaire, Central Africa: comparative evaluation of serology, PCR, and significance of indeterminate western blot pattern

The frequency of indeterminate Western blot (WB) seroreactivities against HTLV-I "gag encoded proteins" only, and the use of low specific diagnostic WB criteria led to the overestimation of HTLV-I seroprevalence in initial studies in intertropical Africa and Papua New Guinea. In order to clarify the meaning of such seroreactivity, 98 blood samples of individuals from a high HTLV-I endemic area in Zaire, Central Africa were studied by a WB assay containing HTLV-I disrupted virions enriched with a gp 21 recombinant protein and a synthetic peptide from the gp 46 region (MTA-1), and by the polymerase chain reaction (PCR) with 3 primers pairs and 4 different HTLV-I and or HTLV-II-specific probes. These 98 samples were taken mainly from patients with neurological diseases and from their relatives. Using stringent WB criteria, 28 sera (29%) were considered as HTLV-I-positive, 3 as negative and 67 (68%) as indeterminate. A large proportion of these indeterminate sera would have been considered as HTLV-I-positive samples according to previous low specific WB diagnostic criteria. After PCR, 35 samples (36%) were considered as positive for the presence of HTLV-I proviral DNA. Out of the 67 WB seroindeterminate, 10 (15%) were found HTLV-I-positive by PCR. These 10 individuals exhibited in WB multiple band reactivity with p19 and/or p24 (7 cases of both) associated in 6 cases with rgp 21, but never with MTA-1. No samples were found PCR-positive for HTLV-II despite the findings of 11 sera suggestive of HTLV-II by WB.(ABSTRACT TRUNCATED AT 250 WORDS)