Antibodies to adult T-cell leukemia virus (ATLV/HTLV-I) in AIDS patients and people at risk of AIDS in Germany

Human retroviruses

It was only in 1980 that the first human retrovirus, HTLV-1, was isolated. Since then, HTLV-2, HIV-1 and HIV-2 have been identified. All four viruses are transmitted with varying efficiency sexually, vertically from mother to infant, and through blood by transfusion or contamination. HTLV-1 is endemic in populations in south-west Japan, Taiwan, sub-Saharan Africa, the Caribbean, southern USA, central and south America, Australia, Papua New Guinea, Solomon Islands and western Asia. There is now epidemic spread amongst IVDUs in north and south America and southern Europe. HTLV-1 is the aetiological agent of adult T-cell leukaemia/lymphoma (ATL) and tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM). Other associations which may be causative are with polymyositis, infective dermatitis, gastrointestinal malignant lymphoma and chronic lymphatic leukaemia. ATL appears to be due to malignant transformation of HTLV-1 infected cells, and TSP/HAM to chronic activation of these cells. The epidemiology of HTLV-2 is being separated only recently from HTLV-1 through the application of PCR. It has a low level of endemicity in populations of central Africa, and central and south America. It is being spread epidemically amongst IVDUs in north America and southern Europe. Its association with any pathology in man remains uncertain. HIV-1 is epidemic and spreading rapidly throughout the world. In areas where homosexual contact was the predominant mode of transmission, heterosexual spread is becoming increasingly important. The areas where heterosexual contact is the predominant mode of transmission include the worst affected populations in the world, for example sub-Saharan Africa and some of the Caribbean. There have been recent and explosive increases of HIV-1 seroprevalence in IVDUs and female prostitutes in Asia, especially Thailand and India. Of the diverse pathology following infection, only the haematological consequences are reviewed in detail: these include anaemia, leucopenia, thrombocytopenia, disorders of coagulation and lymphomas. HIV-2, compared to HIV-1, is less infectious and causes less immunosuppression with more slowly progressive disease. It is prevalent in west Africa, but is spreading, albeit slowly, far beyond.

Human immunodeficiency virus and human T-cell leukemia virus type I in patients undergoing maintenance hemodialysis in Miami

The high prevalence of human immunodeficiency virus (HIV-1) infection in populations at risk in Miami prompted a seroepidemiologic study of both HIV-1 and the human T-cell leukemia virus type I (HTLV-I), a closely related virus, in our patients receiving chronic hemodialysis. One hundred twenty-nine patients undergoing hemodialysis in 1986 and 1987 were tested for antibody against both viral antigens by EIA (Abbott Laboratories, Abbott Park, IL). Seroreactive samples for HIV-1 and/or HTLV-I were confirmed by Western blot and, for HTLV-I, by viral cultures. Thirty patients (23.2%) were positive for retroviral infection (22 for HIV-1 alone, four for HTLV-I alone, and four for both HIV-1 and HTLV-I). The most important risk factor was intravenous drug use, followed by blood transfusion. Patients with HIV-1 had lower T4-T8 ratios and higher mortality than those with HTLV-I infection alone. It was concluded that HTLV-I, as well as HIV-1, infection is endemic in chronic dialysis centers in Miami. The clinical consequences of HTLV-I infection in relatively immunocompromised patients with chronic uremia who are undergoing chronic hemodialysis remains to be established.

Human T-cell leukemia virus type I (HTLV-I) and blood transfusion

Human T-cell leukemia (or T-lymphotropic) virus type I (HTLV-I) is a human exogenous infectious retrovirus of the family Retroviridae. This virus has been associated with adult T-cell leukemia and endemic myelopathies (tropical spastic paraparesis and HTLV-I associated myelopathy). HTLV-I is transmitted by sexual contact, from mother to child, by intravenous drug abuse, and by blood transfusion. The estimated lifetime risk of developing disease in antibody-positive patients is 1 in 80, and a latency period as long as 20 years can intervene. No case of transfusion-transmitted disease has been reported to date. Currently, no testing of blood donors for HTLV-I is required in the United States, and no such test has been approved by the Food and Drug Administration. Because data on the natural history of this virus may take years to accumulate, it is probably wise to begin excluding anti-HTLV-I-positive units from the blood supply in the United States as soon as a licensed test is available.

Possible aetiological factors in leukaemias in Africa

The hypothesis that the true incidence of c-ALL is relatively uniform throughout the world is not supported by experience in tropical Africa, where ALL is uncommon under five years of age. A high rate of spontaneous somatic mutation in pre-B cells may initiate the development of c-ALL, but its progress could be determined by (i) a leukaemogenic agent causing a second genetic event, (ii) the effects of intense antigenic barrage, either stimulating or suppressing pre-B-cell mitosis, or (iii) genetic determinants. Epidemiological patterns in populations of low, intermediate and high socio-economic status may be classified I-III with increasing incidence of diagnosed T-ALL in children over five years and c-ALL in younger children, and subclassified A and B with decreasing incidence of BL. There may be two forms of AML, one similar to that seen in industrialized countries, the other occurring at high prevalence in African children of low socio-economic status, often presenting with chloroma, and perhaps associated with immune suppression secondary to malnutrition, malaria and other intercurrent infections. Uncontrolled exposure to petroleum and other chemicals, and the use of alkylating agents in treatment of neoplasms in young patients could emerge as important causes of ANLL in Africa. There are two varieties of CLL also, one similar to that seen in the western world, the other prevalent in adults below 45 years of age, especially women: transmission of a leukaemogenic agent is postulated, to which women are more susceptible due to immunosuppression during normal pregnancy. The human population and some subhuman primates of subSaharan Africa are the largest reservoir of HTLV-1, which shows association with B-CLL over 50 years of age and ATL.

Multiple sclerosis and human T-cell lymphotropic retroviruses: negative serological results in 135 German patients

A total of 135 sera and 18 cerebrospinal fluid (CSF) samples from patients with multiple sclerosis (MS) were screened for antibodies to human T-cell lymphotropic virus type I (HTLV-I) and human immunodeficiency virus (HIV) by ELISA tests. None of the sera or CSF reacted with HIV antigens. Only 3 out of 135 MS sera but no MS CSF showed increased reactions in the ELISA test for HTLV-I. However, these positive reactions were classified as non-specific by immunoprecipitation. Thus no serological evidence for infection with HIV, HTLV-I, or a related retrovirus was found in the MS patients.

Absence of HTLV I from New Zealand

Sera from 1,943 individuals from Auckland, New Zealand, were tested for the presence of serum antibodies to human T cell lymphotropic virus I (HTLV I), mainly with an enzyme-linked immunosorbent assay (ELISA) with cell extracts as target antigen. The individuals tested were blood donors and mostly Caucasian, but included indigenous Maoris and representatives of several groups of Pacific islanders now resident in New Zealand. Also included were 37 patients with various hematological malignancies, including seven with T cell leukemias. Although 1% of samples were positive by ELISA, none of these were confirmed as positives by Western blotting. On the basis of these results we consider that it is unlikely that HTLV I infection occurs in Auckland; however, we cannot exclude the possibility that pockets of virus infection may occur in other parts of New Zealand or the South Pacific.

Antibodies to HTLV-I in Nigerian blood-donors, their relatives and patients with leukaemias, lymphomas and other diseases

Antibodies to HTLV-I have been detected in sera from 15 (2.0%) of 736 adult blood-donors in Nigeria, in 4 (20.0%) of 20 patients with chronic lymphatic leukaemia, 3 (10.0%) of 30 with non-Hodgkin's lymphoma, one of 12 with Burkitt's lymphoma and one of 7 with acute lymphoblastic leukaemia. The frequency of positivity was higher (3.6%) in the blood-donors from the guinea and wooded savanna of northern Nigeria than in those from the rain-forest and mangrove swamps of southern Nigeria (1.8% in Lagos and 0.7% in Calabar). Two of the 3 seropositive patients with lymphoma had clinical presentation and courses similar to those of Japanese and Caribbean patients with adult T-cell leukaemia/lymphoma.

Serological differences between human T-lymphotropic virus type-I (HTLV-I) and HTLV-III/LAV

Sera from each of five preselected groups of patients with acquired immune deficiency syndrome (AIDS), AIDS-related complex (ARC), hemophilia, adult T-cell leukemia (ATL), and healthy controls were examined for antibodies to human T-cell leukemia (T-lymphotropic) virus type-I (HTLV-I) and HTLV-III by indirect immunofluorescence (IF) and radioimmunoprecipitation (RIP) methods. All sera from five patients with AIDS, ARC, and hemophilia reacted at titers from 1 : 512 to 1 : 5,120 with fixed H9/HTLV-III cells by IF but not with fixed MT-1 cells carrying HTLV-I. Similarly, sera from patients with AIDS, ARC, and hemophilia precipitated HTLV-III-specific polypeptides of 120K, 46K, and 24K. In contrast, sera from five patients with ATL did not react with fixed H9/HTLV-III cells, but reacted with fixed MT-1 cells. Moreover, HTLV-I-specific polypeptides of 68K, 28K, and 24K were precipitated with sera from ATL-patients but not with anti-HTLV-III-positive sera. Recently, we infected HTLV-I-carrying MT-4 cells with HTLV-III and provoked strong cytopathic effects. This system enabled testing for neutralizing antibodies to HTLV-III. Neutralizing titers to HTLV-III of five anti-HTLV-III-positive sera ranged from 1 : 720 to 1 : 9,000. In contrast, all five seronegative controls showed no or only low reactivity to HTLV-III envelope (1 : 80 and 100). However, three out of five anti-HTLV-I-positive sera exhibited weak cross-reactivities with HTLV-III. The reactivities were expressed as less than 1 : 160, except for one case (1 : 720). They were considered to be nonspecific since they were negative for HTLV-III antibodies in the radioimmunoprecipitation studies.

Structural analysis of p19 and p24 core polypeptides of primate lymphotropic retroviruses (PLRV)

Core polypeptides of primate lymphotropic retroviruses (PLRV) have very similar molecular weights. To discriminate between individual PLRVs we have compared two-dimensional tryptic peptide maps of 125I-labeled core polypeptides p19 and p24 of 11 isolates originating from humans and six simian species. Peptide maps showed homologies between all the simian viruses and the human isolates, but they were completely different from those of human T-cell leukemia virus type III (HTLV-III). In general p24s are more conserved than p19s. According to the relationship of their peptide maps we have classified the PLRVs into three groups, the human and chimpanzee isolates, macaque viruses, and green monkey virus.

A glycopolypeptide (gp 100) is the main antigen detected by HTLV-III antisera

Sera from homosexuals and hemophiliacs in Germany were examined for antibodies to human T-lymphotropic retrovirus type III (HTLV-III) by an enzyme-linked immunosorbent assay (ELISA) against purified virus. ELISA positive sera were used to search by immunoprecipitation for HTLV-III related antigens in a persistently infected human T-cell line. A glycopolypeptide with a mol. wt. of 100 000 was regularly recognized by all positive sera. In analogy to glycosylation and high antigenicity of envelope polypeptides of other mammalian retroviruses, gp 100 seemed to be related to the env gen. Two polypeptides with mol. wts. of 24 000 and 22 000 probably representing viral core polypeptides were additionally detected by sera with high ELISA titers.

Antibodies to ATLV/HTLV-1 in Africa

Almost 4000 sera from seven African states were examined for antibodies to ATLV/HTLV-1. Between 1% and 8% of healthy people from sub-Saharan Africa have such antibodies. The highest frequency was observed in Gabon. There were considerable variations between villages. The percentage of seropositives and the mean titre increased with age. Our findings suggest that the African continent is the largest endemic area for ATLV.