Low numbers of intestinal Shiga toxin-producing E. coli correlate with a poor prognosis in sheep infected with bovine leukemia virus.

Healthy ruminants carry intestinal Shiga toxin (Stx)-producing Escherichia coli (STEC). Stx has antiviral activities in vitro and STEC numbers correlate with reduced early viremia in sheep experimentally infected with bovine leukemia virus (BLV). This study assessed the impact of intestinal STEC on BLV-induced disease for one year post-BLV-challenge. High STEC scores (CFU/g feces x frequency of STEC-positive samples) correlated with good health, whereas poor weight gain, distress, and tumor development occurred only among animals with low STEC scores. STEC carriage was associated with increased percentages of B cells in peripheral blood.

Low numbers of intestinal Shiga toxin-producing E. coli correlate with a poor prognosis in sheep infected with bovine leukemia virus

Healthy ruminants carry intestinal Shiga toxin (Stx)-producing Escherichia coli (STEC). Stx has antiviral activities in vitro and STEC numbers correlate with reduced early viremia in sheep experimentally infected with bovine leukemia virus (BLV). This study assessed the impact of intestinal STEC on BLV-induced disease for one year post-BLV-challenge. High STEC scores (CFU/g feces x frequency of STEC-positive samples) correlated with good health, whereas poor weight gain, distress, and tumor development occurred only among animals with low STEC scores. STEC carriage was associated with increased percentages of B cells in peripheral blood.

Serological and nucleic acid analyses for HIV and HTLV infection on archival human plasma samples from Zaire.

In order to better understand the genomic diversity and molecular phylogeny of the human retroviruses, the plasmas from 250 Zairean patients collected in 1969 were tested for antibodies to human T-cell lymphoma and human immunodeficiency viruses (HTLV or HIV) using ELISA and confirmatory Western blots and for viral nucleic acids by reverse transcriptase-directed PCR (RT-PCR). Interestingly, none of the patients was confirmed positive for HIV, even though this region is now endemic for HIV-1. However, 74 (30%) and 3 (1%) of the samples were positive for antibodies to HTLV-I and II, respectively. Forty-four of 74 (59%) Western blot-positive Zairean samples were RT-PCR positive for HTLV-I, while 1 of 3 (33%) of HTLV-II-seropositive samples was RT-PCR positive. On the contrary, none of the Western blot-negative or indeterminate samples were RT-PCR positive for either HTLV-I or HTLV-II. We have cloned and sequenced 140 bp of the pol gene flanked by SK110/SK111 from 8 HTLV-I- and 1 HTLV-II-positive archival samples from Zaire. The HTLV-I isolates from Zaire cluster together as a phylogenetic group, diverging from the prototype Japanese HTLV-I (ATK) by a range of 1.4 to 3.6%. Their close homology to some African STLV-I isolates suggests relatively recent interspecies transmission. The Zairean HTLV-II isolate is closely grouped with the HTLV-II substrain of isolates found in Paleo-Amerindians of the New World, making it unlikely that it represents an endemic African strain.

Epidemiology and etiopathology of human T-lymphotropic viruses: diagnostic and clinical implications for non-endemic areas.

Human T-lymphotropic viruses (HTLV) type I and II were first described more than a decade ago. HTLV-I epidemiology and etiopathology are more defined than those of HTLV-II, but conflicting results have been obtained in seroepidemiologic surveys, mainly for difficulties in the discrimination between the two infections. The introduction of advanced serologic and molecular assays has recently provided sensitive and specific tools for diagnosis, and the epidemiologic and etiopathologic patterns linked to these retroviruses are being more precisely defined. Moreover, extensive nucleotide sequence analyses performed so far have mainly focused on HTLV-I isolates. The recent discovery of new HTLV-II endemic areas and the isolation of HTLV-II strains from intravenous drug users have finally provided the material for the molecular characterization of HTLV-II isolates, which is now a rapidly envolving field. We review the diagnostic strategies available and the etiologic associations reported so far for both viruses and also discuss the occurrence and significance of indeterminate serologic reactivities observed in both endemic and non-endemic areas.

[A new variant of the simian T-lymphotropic retrovirus type I (STLV-IF) in the Sukhumi colony of hamadryas baboons]. / Novyi variant obez'ian'ego T-limfotropnogo retrovirusa pervogo tipa (STLV-1F) v Sukhumskoi kolonii pavianov gamadrilov.

Polymerase chain reaction (PCR) was developed for the detection of simian T-lymphotropic virus type 1 (STLV-1) infection of P. hamadryas and direct sequencing using oligo-nucleotide primer pairs specific for the tax and env regions of the related human T-lymphotropic virus type 1 (HTLV-1). Excellent specificity was shown in the detection of STLV-1 provirus in infected baboons by PCR using HTLV-1-derived primers. The nucleotide sequences of env 467bp and tax 159bp of the proviral genome (env position 5700-6137, tax position 7373-7498 HTLV-1, according to Seiki et al., 1983) derived from STLV-1-infected P. hamadryas were analysed using PCR and direct sequencing techniques. Two STLV-1 isolates from different sources (Sukhumi main-SuTLV-1 and forest stocks-STLV-1F) were compared. Two variants of STLV-1 among P. hamadryas with different level of homology to HTLV-1 were wound (83.8% and 95.2%, respectively). A possible role of nucleotide changes in env and tax sequenced fragments and oncogenicity of STLV-1 variants is discussed.

Human T-lymphotropic virus type I (HTLV-I) provirus-related DNA sequences in peripheral blood mononuclear cells of a patient, in the absence of a definite serological positivity.

The true extent of human T-lymphotropic virus type I and II (HTLV-I/II) infection in European countries and its pathogenetic potential are still unknown. To find out more about HTLV-I/II incidence in our area we studied a group of 160 outpatients attending a sexually transmitted disease clinic over a six-month period. All patients were screened for the presence of specific antibody by means of enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB) analysis, using commercially available reagents. A surprisingly high percentage of patients showed an antibody reactivity to HTLV-I/II antigens by ELISA (9.3%) and IB (6.8%), although none of the samples satisfied the internationally accepted criteria of serological positivity. All subjects, irrespective of doubtful and inconclusive serological results, were further analyzed for the presence of proviral DNA in peripheral blood mononuclear cells by polymerase chain reaction using different pairs of primers and probes. A clear cut positive result for the presence of HTLV-I provirus-related DNA sequences was obtained in peripheral blood mononuclear cells of only one patient, a 26 years old female presenting genital condylomatosis, with no history of blood transfusion and/or intravenous drug abuse. Her serum showed a borderline result at ELISA and an IB reactivity only against p21. These data are open to various possible interpretations and, among others, may represent a hint for the presence of divergent antigenic variants of HTLV-I in the geographical area investigated.

Failure to detect human T-lymphotropic virus antibody in wild-caught New World primates.

We conducted a study to look for a simian counterpart of human T-lymphotropic virus (HTLV) in wild-caught monkeys in the Republic of Panama. Serum specimens were obtained from 102 monkeys (Ateles fusciceps, n = 75; Alouatta villosa, n = 18; and Cebus capucinus, n = 9) captured in Panama's Darien rain forest in 1979-1980. Specimens were screened for HTLV antibody by enzyme-linked immunosorbent assay, and reactive specimens were further tested by Western blot. None of the 102 specimens were seropositive for HTLV. Our findings provide no evidence for an HTLV-like virus in New World primates from Panama, but the sample size was small, and further studies are warranted.

Relationship between the anti-HTLV-1 antibody level, the number of abnormal lymphocytes and the viral-genome dose in HTLV-1-infected individuals.

Two distinct diseases, adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), develop in a minor population of HTLV-1 carriers. We examined the relationship between the viral genome dose in the peripheral-blood mononuclear cells and the serological response in HTLV-1 carriers and patients with HAM/TSP. The antibody titer to HTLV-1 gag and env proteins, as well as the frequency of an antibody response to viral protein p40tax and the titer, increased with increasing viral genome dose. However, the number of abnormal lymphocytes was not directly related to the host viral load. Patients with HAM/TSP generally showed a higher genome dose than healthy carriers and also had higher antibody titers than healthy carriers with the same HTLV-1 load, supporting the existence of an augmented immune response in these patients. These findings suggest that the antibody titer to HTLV-1 genome products, and not the number of abnormal lymphocytes, intimately reflects the approximate viral load in HTLV-1-infected individuals.

Detection of human immunodeficiency virus type 2 in brain tissue.

Infection due to human immunodeficiency virus (HIV) type 2 is believed to cause a clinical picture similar to that of HIV-1, although extensive data are not available. In 2 patients with West African exposure and neurologic symptoms, HIV-2 was detected in the central nervous system using DNA and RNA polymerase chain reaction, in situ hybridization, and immunohistology. In the first patient, the neurologic disease was most likely due to productive infection with HIV-2. In the second, a combination of neuropathologic abnormalities (including the presence of HIV-2) explained the clinical features. Thus HIV-2, like HIV-1, can be readily detected in brain tissue in patients with neurologic abnormalities, although the exact role of HIV-2 in pathogenesis of AIDS-associated neurologic disease requires further study.

Retroviruses and nervous system disease.

During the past decade retroviruses have been recognized as causes of human neurological disease. A wide clinical spectrum of neurological and neuromuscular diseases have been reported with HIV infections, and studies of these diseases have raised novel and exciting hypotheses of pathogenesis. As yet the full clinical spectrum of diseases associated with HTLV-1 has yet to be defined, and the pathogenesis of the chronic spastic paraparesis remains a mystery. Chronic neurological diseases in animals caused by both oncoviruses and lentiviruses can provide some clues to the pathogenesis of these newly recognized human neurological illnesses.

Detection of human T-cell leukemia/lymphoma virus, type II, in a patient with large granular lymphocyte leukemia.

We studied a patient with large granular lymphocyte (LGL) leukemia for evidence of human T-cell leukemia/lymphoma virus (HTLV) infection. Serum from this patient was positive for HTLV-I/II antibodies by enzyme-linked immunosorbent assay (ELISA) and was confirmed positive in Western blot and radioimmunoprecipitation assays. Results of a synthetic peptide-based ELISA showed that the seropositivity was caused by HTLV-II and not HTLV-I infection. Analyses of enzymatic amplification of DNA from bone marrow sections using the polymerase chain reaction (PCR) were positive for HTLV-II specific gag, pol, env, and pX gene sequences. Cloning and sequencing of amplified products showed that the HTLV-II pol and pX sequences in patient DNA differed from the sequences of 17 other HTLV-II isolates examined in our laboratory. HTLV infection may have a role in some patients in the pathogenesis of LGL leukemia.

Multiple isolates and characteristics of human T-cell leukemia virus type II.

Human T-cell leukemia (or lymphotropic) virus type II (HTLV-II) was isolated from eight HTLV-seropositive patients, six of whom were also infected with human immunodeficiency virus, by cocultivation of peripheral blood mononuclear cells (PBMCs) with BJAB, a continuous B-cell line. Restriction endonuclease mapping of the proviruses demonstrated consistent differences among isolates, and two distinct physical map patterns were observed. The results suggest the existence of two closely related molecular subtypes of HTLV-II, which are tentatively designated HTLV-IIa and HTLV-IIb. This finding was supported by preliminary nucleotide sequence analysis of the env gene region encoding the transmembrane glycoprotein gp21, which showed consistent differences between the two proposed virus subtypes. Exploitation of differences in restriction endonuclease sites allowed polymerase chain reaction amplification to detect and differentiate the two subtypes in fresh PBMCs of HTLV-seropositive intravenous drug abusers (IVDAs). The results of these studies confirm that HTLV-II infection is the prominent HTLV infection in seropositive IVDAs and also show that infection with both subtypes occurs. The finding of genetic heterogeneity in the HTLV-II group of viruses may have important implications for studies on its role in human disease and will be useful in characterizing the viruses present in newly discovered endemic foci in New World indigenous populations.

Infection of rats with HTLV-1: a small-animal model for HTLV-1 carriers.

A human T-cell line producing human T-cell leukemia virus type I (HTLV-I), MT-2, was injected intravenously into female F344 rats aged 5 weeks to make HTLV-I carrier rats. Antibody against HTLV-I was detected at the 5th week after MT-2 injection, and its titer reached a high plateau which continued from the 15th to the 27th week. The antibodies were against p19, p24, p28 and p53 of HTLV-I antigens from MT-2 cells. The gag, pX and LTR nucleotide sequences of HTLV-I provirus were demonstrated by using polymerase chain reaction (PCR) in the peripheral-blood mononuclear cells of 3 rats at the 44th week and 2 at the 66th to 68th week out of 8 F344 rats injected with MT-2 cells. Quantification of the HTLV-I proviral sequence revealed that 30 to 60 molecules were present in 10(5) peripheral-blood mononuclear cells, indicating that the rats were chronically infected with HTLV-I. HTLV-I-infected rats could serve as a small-animal model for studying the pathophysiological state of HTLV-I carriers and also that of HTLV-I infection on various HTLV-I-related diseases, including adult T-cell leukemia and HTLV-I-associated myelopathy.

HTLV-1 envelope sequences from Brazil, the Caribbean, and Romania: clustering of sequences according to geographic origin and variability in an antibody epitope.

We sequenced the envelope genes of Human T-cell leukemia type I viruses (HTLV-I) derived from five Brazilian, two Caribbean, and one Romanian case of adult T-cell leukemia after amplification of the complete env gene by PCR. A comparison with previously reported HTLV-I sequences revealed that, although highly homologous, no two env sequences were identical. All envelope sequences differed from each other by 0.3-2.1% nucleotide differences. The five Brazilian sequences clustered together and were about as different from each other (0.5-0.75% nucleotide difference) as were three previously reported Japanese sequences (0.7-0.95%). In contrast, sequences of Caribbean origin were less homogeneous (0.5-1.9% nucleotide differences within this group). The Romanian sequence was not significantly more divergent than any of the others and was closest to our two Caribbean sequences. We observed two changes in a region (aa 176-209) which has previously been shown to contain a linear antibody epitope recognized by most human sera from seropositive individuals. One of these changes affects the binding of monoclonal antibodies to this epitope demonstrating the variability of an antibody epitope in the HTLV-I envelope.