Investigation of retroviral involvement in chronic fatigue syndrome

Within the last few years significant efforts have been made to identify objective reliable diagnostic markers from individuals with chronic fatigue syndrome (CFS). We report the absence of a previously described retroviral marker (HTLV-II gag) in a blinded study of CFS cases. Even with excellent reproducible sensitivities, this marker failed in repeated attempts to distinguish cases from controls. In addition, four other retroviruses (simian T cell leukaemia virus, human spumavirus, bovine leukaemia virus and simian retrovirus) were examined for their presence in these CFS cases and found to be absent. Our findings suggest that these agents, at least as markers, are non-distinguishing for CFS and that other factors may be confounding the resolution of an aetiology to this syndrome.

No genetic evidence for involvement of Deltaretroviruses in adult patients with precursor and mature T-cell neoplasms

Background

The Deltaretrovirus genus comprises viruses that infect humans (HTLV), various simian species (STLV) and cattle (BLV). HTLV-I is the main causative agent in adult T-cell leukemia in endemic areas and some of the simian T-cell lymphotropic viruses have been implicated in the induction of malignant lymphomas in their hosts. BLV causes enzootic bovine leukosis in infected cattle or sheep. During the past few years several new Deltaretrovirus isolates have been described in various primate species. Two new HTLV-like viruses in humans have recently been identified and provisionally termed HTLV-III and HTLV-IV. In order to identify a broad spectrum of Deltaretroviruses by a single PCR approach we have established a novel consensus PCR based on nucleotide sequence data obtained from 42 complete virus isolates (HTLV-I/-II, STLV-I/-II/-III, BLV). The primer sequences were based on highly interspecies-conserved virus genome regions. We used this PCR to detect Deltaretroviruses in samples from adult patients with a variety of rare T-cell neoplasms in Germany.

Results

The sensitivity of the consensus PCR was at least between 10^-2 and 10^-3 with 100% specificity as demonstrated by serial dilutions of cell lines infected with either HTLV-I, HTLV-II or BLV. Fifty acute T-cell lymphoblastic leukemia (T-ALL) samples and 33 samples from patients with various rare mature T-cell neoplasms (T-PLL, Sézary syndrome and other T-NHL) were subsequently investigated. There were no cases with HTLV-I, HTLV-II or any other Deltaretroviruses.

Conclusion

The results rule out a significant involvement of HTLV-I or HTLV-II in these disease entities and show that other related Deltaretroviruses are not likely to be involved. The newly established Deltaretrovirus PCR may be a useful tool for identifying new Deltaretroviruses.

Discovery of a new human T-cell lymphotropic virus (HTLV-3) in Central Africa

Human T-cell Leukemia virus type 1 (HTLV-1) and type 2 (HTLV-2) are pathogenic retroviruses that infect humans and cause severe hematological and neurological diseases. Both viruses have simian counterparts (STLV-1 and STLV-2). STLV-3 belongs to a third group of lymphotropic viruses which infect numerous African monkeys species. Among 240 Cameroonian plasma tested for the presence of HTLV-1 and/or HTLV-2 antibodies, 48 scored positive by immunofluorescence. Among those, 27 had indeterminate western-blot pattern. PCR amplification of pol and tax regions, using HTLV-1, -2 and STLV-3 highly conserved primers, demonstrated the presence of a new human retrovirus in one DNA sample. tax (180 bp) and pol (318 bp) phylogenetic analyses demonstrated the strong relationships between the novel human strain (Pyl43) and STLV-3 isolates from Cameroon. The virus, that we tentatively named HTLV-3, originated from a 62 years old Bakola Pygmy living in a remote settlement in the rain forest of Southern Cameroon. The plasma was reactive on MT2 cells but was negative on C19 cells. The HTLV 2.4 western-blot exhibited a strong reactivity to p19 and a faint one to MTA-1. On the INNO-LIA strip, it reacted faintly with the generic p19 (I/II), but strongly to the generic gp46 (I/II) and to the specific HTLV-2 gp46. The molecular relationships between Pyl43 and STLV-3 are thus not paralleled by the serological results, as most of the STLV-3 infected monkeys have an "HTLV-2 like" WB pattern. In the context of the multiple interspecies transmissions which occurred in the past, and led to the present-day distribution of the PTLV-1, it is thus very tempting to speculate that this newly discovered human retrovirus HTLV-3 might be widespread, at least in the African continent.

A journey with T cells, primate/human retroviruses and other persisting human T-cell tropic viruses

A study of the growth of primate/human T cells led to mechanisms for temporary laboratory culture of these cells (discovery of interleukin-2) and also their continuous culture (by immortalization after infection with human T-cell lymphotropic virus type 1 or 2 (HTLV-1 or 2)). Cultures of lymphocytes also led us to isolate five persisting T-tropic viruses: 1. the Hall's Island strain of gibbon ape leukemia virus, 2. HTLV-1, 3. HTLV-2, 4. human immunodeficiency virus and 5. human herpes virus-6 (HHV-6). This report is a brief synopsis of the discoveries of the first human retroviruses, the HTLV.

Current prevalence and incidence of infectious disease markers and estimated window-period risk in the American Red Cross blood donor population

BACKGROUND

There has been continuing progress in measures to reduce the risk of transfusion-transmitted infection, including introduction of serologic tests of increased sensitivity and the recent implementation of investigational NAT in small pools of samples.

STUDY DESIGN AND METHODS

Data relating to all blood donations to the American Red Cross have been consolidated into a single database. The prevalence of confirmed-positive test results for HBsAg, HCV, HIV, and HTLV were evaluated for each year for first-time donors from 1995 through 2001. Incidence rates for these infections were evaluated among repeat donors having at least two donations in a 2-year period. The frequencies of HIV-1 RNA- and HCV RNA-positive, seronegative donations were assessed for first-time and repeat donations. The relationship risk = (window period) x (incidence) was used to assess residual risk among repeat donations and to evaluate the incidence of HCV and HIV infection among first-time donors.

RESULTS

During the study period, prevalence rates for all markers declined significantly over time: in 2001, the rates per 100,000 were 75.6 for HBsAg, 299 for HCV, 9.7 for HIV, and 9.6 for HTLV; the corresponding incidence rates (/100,000 person-years) were 1.267, 1.889, 1.554, and 0.239, respectively. Estimates of residual risk in donations from repeat donors (after NAT) for HCV and HIV were 1 per 1,935,000 and 1 per 2,135,000, respectively. However, incidence rates for these agents are approximately two times greater among first-time donors. For both HCV and HIV, NAT yield was concordant with that predicted by current window-period models.

CONCLUSION

These data cover about half of all the whole blood collected in the United States. They suggest increasing improvement in transfusion safety and clearly define the benefit of pooled NAT.

Human T-lymphotropic retrovirus type-1 in Thailand

Seroprevalence of antibodies to human T-lymphotropic virus type-1 (HTLV-1) was surveyed among the Thai population by the particle agglutination test and Western blotting test. None of a total of 727 individuals from seven ethnic groups were positive for the specific antibody to HTLV-1. Among hospital based 3,427 subjects in Southern Thailand, one patient with a brain tumor showed positivity in the Western blotting test, however, HTLV-1 proviral genome was not identified by PCR. The present data suggest that HTLV-1 is not endemic in the Thai population and that HTLV-1 is not a major public health problem in Thailand because HTLV-1 rarely causes its associated diseases.

Transfusion virology: progress and challenges

Discoveries of new human viruses and new technologies for their detection have made, and will continue to make, major contributions to the safety of blood transfusion. This article discusses the practical issues involved in the implementation of additional serological screening tests for viruses such as human T-lymphotropic virus, and reviews current information on the prevalence and pathogenicity of more recently discovered viruses, such as hepatitis G virus (HGV) or GB virus-C (GBV-C) and human herpes virus 8, a potential aetiological agent of Kaposi's sarcoma. Progress in the technology behind nucleic acid amplification techniques, such as the polymerase chain reaction (PCR), makes direct detection of viruses such as human immunodeficiency virus and hepatitis C virus possible. The use of such methods for screening will allow the earlier detection of acutely-infected individuals and the elimination of transmission from 'window' period donations before seroconversion for antibody. Establishing a framework for PCR-based screening would also enable the testing for others such as hepatitis A virus, parvovirus B19 and GBV-C/HGV for which serological detection methods cannot be or have not been developed.

HTLV testing in blood transfusion

To improve the safety of the blood supply, HTLV screening of blood donations became mandatory in different countries. In Japan and in Europe, the majority of HTLV-infected donors are HTLV-1 whereas in the USA more than half of them are HTLV-II-positive. The prevalence of HTLV-infected donors is low in European Countries as is the rate of seroconversion. Consequently, to test donors only once would have a high efficiency. This procedure is already in use in certain countries. Furthermore, if the use of leucodepleted cell concentrates is generalized, the policies of HTLV screening will still be further modified.

CD30-positive cutaneous large cell lymphomas. A comparative study of clinicopathologic and molecular features of 16 cases

The authors have analyzed and compared the clinicopathologic and molecular features of 16 cases of large cell cutaneous lymphomas expressing CD30 antigen. Three main clinical groups were defined: (1) a group of localized skin disease (7 cases); (2) a group of multicentric skin disease (5 cases); and (3) a group of concomitant skin and extracutaneous disease. Good prognosis was associated with localized skin disease and no history of lymphoma. Interestingly, a majority of Reed Sternberg-like cells was only observed in this group (5 of 6 cases). The two other groups did not show distinctive evolutive nor morphologic features. Southern blot and/or polymerase chain reaction (PCR) technique showed clonality and a T-cell genotype in respectively 13 of 14 and 12 of 12 analyzed cases. Viral infection of tumoral cells was investigated by PCR, in situ hybridization (ISH) or electron microscopy. Epstein-Barr virus (EBV) sequences were detected by PCR and ISH in tumoral cells of cutaneous lesions in one case of skin lymphoma with extracutaneous spreading. No EBV sequence was detected by ISH in the localized lymphomas, whereas HIV particles were visible in tumoral cells in one of these cases. No human T-cell lymphotropic virus (HTLV) tax sequence was amplified by PCR in any case of our series. Our results confirm that CD30-positive cutaneous large cell lymphomas are different clinical and molecular entities. However, a combined clinical and morphologic analysis may help to identify a subset of CD30 cutaneous lymphomas with favorable prognosis.

Viruses and Langerhans cell histiocytosis: is there a link?

As a rare, sporadic disease Langerhans cell histiocytosis (LCH) presents a difficult problem in defining a likely etiology. Epidemiological data would not a priori lead one to choose a viral etiology. However, there are rare tumours which occur as sequelae of common infections from Epstein-Barr virus or human papilloma viruses. Likewise some viruses can cause cells to elaborate cytokines which could ultimately stimulate Langerhans cell growth. There is only a small amount of experimental data testing the hypothesis that viruses might be associated with LCH. The theoretical constructs surrounding this question and new data refuting the association are summarised.

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.

A primate T-lymphotropic virus, PTLV-L, different from human T-lymphotropic viruses types I and II, in a wild-caught baboon (Papio hamadryas)

Searching for clues to the evolution of the primate T-lymphotropic viruses (PTLVs), which include the human and the simian T-lymphotropic viruses (HTLV and STLV), we have identified another PTLV, which differs sufficiently from the known PTLV-I and PTLV-II types to be designated here PTLV-L. The virus was isolated from a wild-born baboon (Papio hamadryas) from Eritrea. In a cDNA library a 1802-bp-long fragment was identified that extends from the env region, including the complete transmembrane protein gene, to part of the tax/rex gene. Homologies at the nucleotide sequence level of PTLV-L, prototype simian T-lymphotropic virus-PH969, with HTLV-I and -II, respectively, were 62% and 64% overall, 65% and 70% in the env region, and 80% and 80% in the partial tax/rex sequence. In the 5' part of the pX region a significant homology was seen only with HTLV-II (52%). Phylogenetic analysis based on the gene encoding the transmembrane protein indicates that PTLV-L represents a PTLV type with a long independent evolution, longer than any strain within the PTLV-I or PTLV-II groups. The finding of another PTLV type in African baboons is further evidence of the wide variety of PTLV found on this continent. Whether PTLV-L resembles PTLV-I and PTLV-II in the extension of its host range to other primates, including humans, remains to be seen.

Retrovirus tests of human leukemia/lymphoma cell lines at DSM

Permanently established human cell lines can produce several retroviruses. It is important to routinely test such cell lines for human T cell lymphotropic virus (HTLV) type I and II, and for human immunodeficiency virus (HIV) type 1 and 2 in order to exclude any potential biohazard from cell lines producing human retroviruses. Reverse transcriptase assay, polymerase chain reaction, and dot-blot hybridization of in-vitro amplified DNA with virus-specific probes are used.

Polymerase chain reaction and transfusion microbiology

Polymerase chain reaction (PCR) involves alternate denaturing and re-annealing of DNA in test samples in the presence of appropriate oligonucleotide primers complementary to opposite strands of the target DNA together with a heat-stable DNA polymerase, Mg2+ and the four nucleotide triphosphates. DNA target segments can be 'amplified' ten-millionfold by 25-35 such cycles. Even greater amplification (approximately 10(12)-fold) with enhanced specificity can be obtained by a second set of amplification cycles using a further pair of 'nested' primers sited within the DNA sequence defined by the original primers. PCR can be applied to the study of the whole range of transfusion-transmitted infections, both plasma and cell associated; RNA viruses can be analyzed if a DNA copy is made from the viral RNA by treatment with reverse transcriptase. In a transfusion context, the retroviruses (HIV-1, HIV-2, HTLV-I, HTLV-II), HCV and HBV have been the viruses most intensively subjected to PCR analysis. The advantages of PCR in this context include its ability to detect virus during the 'window period' or seronegative stages of infections and its value as a marker for viraemia and for the detection of viruses in products made from large pools of plasma. True immunity may also be differentiated from persistent infection in the presence of antibody. Similarly, PCR can overcome problems of diagnosis of acute infection caused by the presence of passively transferred antibody. Detailed strain differentiation is also possible by PCR, in conjunction with sequencing or with the aid of restriction endonucleases.(ABSTRACT TRUNCATED AT 250 WORDS)

Absence of HTLV-I/II infection in blood donors with positive and inconclusive HTLV-I/II serology

The pathogenetic potential and the true extent of human T leukemia/lymphotropic virus type I (HTLV-I) and type II (HTLV-II) infection are unknown. To find out more about HTLV-I/II seroepidemiology and the risks of iatrogenic transmission, we performed a serological study, screening 4086 healthy blood donors. A surprisingly high percentage of serum reactivity to HTLV-I/II antigens was observed by commercial ELISA (2.08%) and immunoblotting (IB) (0.85%) analysis, although none of the samples satisfied the (IB) criteria for positivity based on detection of gag protein p24 and at least one env gene product, either gp46 or gp61/68. To clarify these inconclusive results, we performed polymerase chain reaction (PCR) analysis for HTLV-I and HTLV-II provirus detection in peripheral blood lymphocytes, obtained from individuals with an apparent pattern of seropositivity. The data obtained by PCR failed to reveal evidence of HTLV-I/II provirus integration in peripheral blood cells, ruling out the possibility of a viral infection in these cases, and pinpointing the limitations of both serological methods used. Our observations suggest that serological assays alone are not a reliable tool for blood donor screening of HTLV-I/II infection and raise the important question of interpreting inconclusive results.

Evaluation of a new generation synthetic peptide combination assay for detection of antibodies to HIV-1, HIV-2, HTLV-I, and HTLV-II simultaneously

A new generation combination test (Detect-Plus, IAF BioChem, Montreal, Canada) based on synthetic peptides for HIV-1, HIV-2, HTLV-I, and HTLV-II was compared with three routine commercial screening assays and confirmatory assays to determine its sensitivity and specificity and to evaluate it as a substitute screening method. Samples from 356 sexually transmitted disease (STD) patients were tested by the four screening tests. All initially reactive samples were retested in duplicate by the corresponding EIA and repeatedly reactive samples were confirmed by Western blots for HIV-1, HIV-2, and HTLV-I/II. The confirmed positives detected by each screening assay were HIV-1 (23/356, 6.46%), HIV-2 (11/356, 3.09%), and HTLV-I/II (5/356, 1.4%). The new generation Detect-Plus test produced only two results (2/356, 0.56%) that were presumed to be false-positives in comparison to the screening tests, but the OD/CO values were just slightly high (1.5 and 1.9). There were no false-negative results, indicating that the sensitivity of the new combination test was excellent (100%). Compared with routine retroviral EIA assays, the test is easy to perform--the total time requirement is only 2 hr and there is no need for incubation equipment. The OD/CO values were very high when samples were positive, making even visual interpretation possible. We conclude that this new combination assay is an excellent screening method for detection of antibodies to the human retroviruses, and may be particularly useful for screening blood for transfusion and in epidemiological investigations.

Prevalence of HTLV infection in the Dominican Republic: association with neurological disease

The presence of the human T-cell leukemia virus (HTLV) in Dominican blood donors and patients with tropical spastic paraparesis (TSP) was first detected in 1987. To define further the seroprevalence in the country, nearly 4,000 samples from high- and low-risk populations, as well as patients with neurological disease and with leukemia or lymphoma were tested for HTLV antibodies. A 1-2% seropositivity rate was found among the low-risk population, a 2-5% in the high-risk, and at least 87% in those with TSP. A few patients with malignancy also had antibodies to HTLV. An increase in seropositivity with age and a predominance of female seropositive individuals were found. Infectious virus was isolated from TSP patients, prostitutes, and family members of index patients. These data indicate the substantial level of HTLV infection in another Caribbean country and its relation to neurologic disease.

The role of HTLV in HIV-1 neurologic disease

We performed a serologic survey for antibodies to HTLV-I/II in the course of a longitudinal study of the neurologic complications of HIV-1 infection. Nine (3.7%) of 242 HIV-1 seropositive subjects and none of 60 HIV-1 seronegative control subjects had antibodies to HTLV-I/II by ELISA. Western blot and polymerase chain reaction confirmed the presence of HTLV-I in 2 subjects and HTLV-II infection in 2 others. Both HIV-1/HTLV-I coinfected subjects and 1 HIV-1/HTLV-II coinfected subject had a slowly progressive myelopathy clinically identical tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). The presence of a myelopathy resembling TSP/HAM in the coinfected subjects suggests that HIV-1 may enhance the expression of neurologic disease caused by HTLV. Patients with a progressive myelopathy occurring in association with HIV-1 infection should be serologically tested for the presence of HTLV. Establishing dual infection has therapeutic and prognostic import as 1 of the HIV-1/HTLV-I subjects substantially improved with corticosteroids and the HIV-1/HTLV-II subject with myelopathy had a marked improvement in the absence of therapeutic intervention.

Human T-cell lymphotropic virus in volunteer blood donors

Serum samples collected in 1985 and 1986 from 18,257 donors to the Greater New York Blood Program were screened by enzyme-linked immunoassay for antibody to human T-cell lymphotropic virus (anti-HTLV). Fifteen samples (0.08%) were confirmed positive: 7 by radioimmunoprecipitation assay (RIPA) alone, 6 by Western blot alone, and 2 by combined results from both tests. One donor, whose original test result was uninterpretable because multiple nonspecific bands were present on RIPA, clearly tested positive on subsequent specimens. Follow-up testing of individuals with this type of result may be needed to resolve their HTLV status. Anti-HTLV prevalence increased with age and was significantly more common in black or Hispanic donors and in those born in the Caribbean than in other donors. All anti-HTLV-positive donors were negative for antibody to HIV-1, and only one donor (7% of those positive) would have been excluded by any of the routine donor screening tests used at that time.

Molecular cloning and complete nucleotide sequence of an adult T cell leukaemia virus/human T cell leukaemia virus type I (ATLV/HTLV-I) isolate of Caribbean origin: relationship to other members of the ATLV/HTLV-I subgroup

We report the first complete nucleotide sequence of an adult T cell leukaemia virus/human T cell leukaemia virus type I (ATLV/HTLV-I) isolate from a British patient of Caribbean origin. Sequence comparisons of our proviral clone (HS-35) with other molecular clones are shown. We note the strong sequence conservation between isolates of Caribbean and Japanese origin (2.3% divergence), but demonstrate the higher homologies existing between isolates originating from similar geographical areas (approximately 1% divergence). Implications for the origin, evolution and dissemination of the ATLV/HTLV-I subgroup are discussed. Analysis of defective proviral clones isolated from the same genomic library is also reported, and suggests a pattern of proviral sequence deletions during the biogenesis of defective proviruses.

Serological and structural comparison of immunodeficiency viruses from man, African green monkey, rhesus monkey and sooty mangabey

We have studied the serological relationship among the human immunodeficiency virus type 1 (HIV-1), and three simian immunodeficiency viruses (SIV). SIVagm was isolated from African green monkeys (Cercopithecus aethiops), and compared with the previously described isolates of SIVmac from a rhesus macaque (Macaca mulatta) and SIVsm from a sooty mangabey (Cercocebus atys). With respect to the glycoproteins, the simian viruses represent a subgroup apparently different from HIV. To classify HIV and SIV isolates further, we compared tryptic peptide maps of the core polypeptides p 18 and p 24 of HIV-2, three HIV-1 and five SIV isolates. Each peptide map was distinguishable, and differences are most prominent between the HIV-1 group and the SIVmac/SIVsm group. HIV-2 is very similar to SIVmac and SIVsm. The three SIVagm isolates form a more heterogeneous group. The p24s of all SIVagms are more similar to the p24s of HIV-1, but with respect to p 18, one isolate is similar to HIV-1, while the two others are more related to SIVmac, SIVsm, and HIV-2.

Seroprevalence and epidemiological correlates of HTLV-I infection in U.S. blood donors

Screening for human T-lymphotropic virus type I (HTLV-I) antibodies was performed on sera from 39,898 blood donors at eight blood centers in geographically distinct areas of the United States. Ten donors (0.025 percent) showed evidence of HTLV-I seropositivity by enzyme immunoassays; this was confirmed by protein immunoblot and radioimmunoprecipitation. Seroprevalence rates ranged from 0 to 0.10 percent at the locations sampled, with HTLV-I antibodies found predominantly in donors from the southeastern and southwestern United States. Matched case-control interviews and laboratory studies were performed on five seropositive women and two seropositive men who participated in an identity-linked collection of sera from a subset of 33,893 donors at six of the eight blood centers. Four of the women and both men are black; one woman is Caucasian. Four of the seven seropositive individuals admitted to prior intravenous drug abuse or sexual contact with an intravenous drug user. Sexual contact with native inhabitants of an HTLV-I endemic area was the only identified risk factor for one male. The distribution of HTLV-I antibodies in this U.S. blood donor sample corroborates the previously reported epidemiology of this agent and suggests that additional donor screening measures, including the testing of donated blood for HTLV-I markers, may be necessary to prevent the spread of HTLV-I to transfusion recipients.

Isolation of human T-lymphotropic virus type I (HTLV-I) from a black South African with Kaposi's sarcoma

Serological evidence for HTLV-I infection in the South African population has now been confirmed by the isolation of the virus from the peripheral blood lymphocytes of an adult Tsonga male. The subject was an indigenous black man from the south-eastern Transvaal who had suffered from Kaposi's sarcoma for a decade and in whom serum antibodies against HTLV-I were demonstrated. T-lymphocyte cell lines were established from his peripheral blood lymphocytes and shown to be productively infected with HTLV-I as evidenced by: the characteristic cell morphology; the typical viral morphogenesis on ultra-thin section electron microscopy; the viral genome in DNA extracted from the cell lines; characteristic reverse transcriptase activity and viral specific proteins in the cell culture supernatant fluids. Spread of infection occurs through sexual intercourse, from mother to child, and by blood transfusion. Donated blood should be screened to contain the spread of HTLV-I infection.

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.

Comparison of simian immunodeficiency virus isolates

Information on the extent of genetic variability among non-human primate lentiviruses related to human immunodeficiency virus (HIV) is sorely lacking. Here we describe the isolation of two molecular clones from the simian immunodeficiency virus (SIV) and their use to derive restriction endonuclease maps of five SIV isolates from rhesus macaques and one from a cynomolgus macaque. Although similar, all six viral isolates are readily distinguishable; the single isolate from a cynomolgus macaque is the most different. The restriction endonuclease map of one macaque isolate (SIVMAC-251) is identical to that published by others for STLV-IIIAGM of African green monkeys and for HTLV-IV of humans. Nucleotide sequences from the envelope region of cloned SIVMAC-251 have more than 99% identify to previously published sequences for STLV-IIIAGM (refs 2, 4) and HTLV-IV (ref. 4). These results and other observations provide strong evidence that isolates previously referred to as STLV-IIIAGM and HTLV-IV by others are not authentic, but were derived from cell cultures infected with SIVMAC-251.

Isolation of an HTLV-1-like retrovirus from patients with tropical spastic paraparesis

Tropical spastic paraparesis (TSP) is a slowly progressive myelopathy associated with increased serum and cerebrospinal fluid antibodies to the human T-lymphotropic retrovirus type I (HTLV-I) (ref. 1), and has been observed in many regions of the world. A similar condition known as HTLV-I-associated myelopathy occurs in the Kagoshima prefecture of Japan. Recent but controversial reports suggest involvement of virus related to HTLV-I in multiple sclerosis. Magnetic resonance imaging and electrophysiological studies indicate that TSP lesions are like multiple sclerosis in that they are disseminated throughout the nervous system. Complete virus from patients with TSP has proved difficult to isolate using techniques successful in adult T-cell leukaemia cases associated with HTLV-I. Here we report the isolation of an HTLV-I-like virus from T-cell lines derived from the peripheral blood and cerebrospinal fluid of TSP patients. The monoclonal antibody OKT3 was used to generate non-transformed T-cell lines that express HTLV-I antigens. Infectious virus was demonstrated by co-cultivation and complete, replicating virions were visualized ultrastructurally.

Nucleotide sequence analysis of a provirus derived from HTLV-1-associated myelopathy (HAM)

Human T-cell leukemia virus type 1 (HTLV-1) is known to be associated with adult T-cell leukemia (ATL). Recently, HTLV-1-associated myelopathy (HAM) was described as a neurological disease with which an etiological association of HTLV-1 is suspected. A provirus genome was cloned from a lymphoid cell line derived from the cerebrospinal fluid of a patient with HAM, in order to examine in detail the etiological virus associated with HAM. The nucleotide sequence of the long terminal repeat (LTR), protease, env and pX regions of the provirus shows over 97% homology with that of HTLV-1 derived from ATL. These results suggest that this provirus, derived from a patient with HAM, belongs to the same species as HTLV-1 derived from patients with ATL.

Human T cell lines established from the cerebrospinal fluid of patients with human T lymphotropic virus type I-associated myelopathy (HAM)

T cell lines were established from the cerebrospinal fluid (CSF) lymphocytes of two patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM). These two interleukin-2 (IL-2)-dependent T cell lines have been cultured for more than 8 months without any accessory cells. The surface phenotype of these cells was CD2(+), CD4(+), CD8(-), Ia(+) and Tac(+). Southern blot hybridization analysis revealed the presence of HTLV-I provirus in these cells and C-type retrovirus particles were identified by electron microscopy. These findings indicate the presence of HTLV-I infected helper T lymphocytes in the CSF of the patients with HAM. These HTLV-I(+) T cell lines may be valuable for investigating the possible neutrotropism of HTLV-I and the role of HTLV-I in the pathogenesis of HAM.

HTLV-I, adult T-cell leukemia, and tropical spastic paraparesis

Human lymphotropic retroviruses have been identified as the etiological agents of adult T-cell leukemia and acquired immunodeficiency syndrome (AIDS). Human T-lymphotropic virus type I (HTLV-I) has been linked to the etiology of ATL, and human immunodeficiency virus type I (HIV-1) has been identified as the cause of AIDS. Both retroviruses are T-cell tropic. HTLV-I is a transforming virus, whereas HIV-1 is a cytopathic virus and kills the cells it infects. HTLV-I has recently been identified from some patients with tropical spastic paraparesis, and it appears that HTLV-I infection alone or in the presence of other cofactors may be important in the development of this neurological dysfunction.

An overview of retrovirus replication and classification

This introductory chapter has presented an overview of how retroviruses replicate and how they are classified within the family Retroviridae. The genomic structure of retroviruses, so reminiscent of bacterial transposons and other similar genetic elements, and reverse transcriptase, which leads to the reverse flow of genetic information from RNA to DNA, are responsible for many of the properties of these viruses which make them both fascinating and important as causes of cancer and other diseases. The requirement for integration shared by most retroviruses leads directly to most of the phenomena resulting from their interaction with target cells. Certainly latency, at the level of the organism, is one such property relevant to how we think of vaccines and therapeutic reagents. The ability of retroviruses to acquire oncogenes from cellular DNA has greatly facilitated our understanding of the genetics of neoplasia. Additionally, the use of retroviral vectors to introduce new genes into genetically defective animals is a consequence of the genetic organization of retroviruses. Classification of viruses at the species level is difficult for several reasons. In particular, viruses do not sexually reproduce in any conventional sense, and it is difficult to identify a population of virions which make up a genetically distinct pool. Thus, the definition of individual species is often controversial and is not necessarily aided by the criteria used to define larger phylogenetic groups. In the latter case, retroviruses have distinctive morphological and biochemical features which allow their classification at the family, subfamily, genus, and subgenus levels. Additional classification occurs by accounting for factors such as host range, cross neutralization, ability to compete in interspecies radioimmunoassays, and genetic homology detected by hybridization under conditions of relaxed stringency. Direct comparison of nucleotide sequences offers the hope that mathematical criteria will be developed that can define the level of differences characteristic of individual species, genuses, and subfamilies.

HTLV-I-like viral particles in spinal cord cells in Jamaican tropical spastic paraparesis

Viral-like particles morphologically identical to human T-lymphotropic virus type I or II, but distinct from human T-lymphotropic virus type III, have been seen by electron microscopy in spinal cord tissue from a Jamaican tropical spastic paraparesis patient who was known to be positive for human T-lymphotropic virus I antibody before death. This is the first electron microscopy report on a patient from an endemic tropical spastic paraparesis region.

The role of HTLV-I in tropical spastic paraparesis in Jamaica

We report clinical and laboratory investigations of 47 native-born Jamaican patients with endemic tropical spastic paraparesis and of 1 patient with tropical ataxic neuropathy. Mean age at onset was 40 years, with a female-male preponderance (2.7:1). Neurological features of endemic tropical spastic paraparesis are predominantly those of a spastic paraparesis with variable degrees of proprioceptive and/or superficial sensory impairment. Using enzyme-linked immunoabsorbent assay (ELISA), IgG antibodies to human T-lymphotropic virus type I (HTLV-I) were present in 82% of sera and 77% of cerebrospinal fluids. On Western blot analysis, IgG antibodies detected the p19 and p24 gag-encoded core proteins in both serum and cerebrospinal fluid. Titers were tenfold higher by ELISA in serum than in cerebrospinal fluid, and some oligoclonal bands present in fluid were not seen in serum. Serum-cerebrospinal fluid albumin ratios were normal, and IgG indexes indicated intrathecal IgG synthesis. Histopathological changes showed a chronic inflammatory reaction with mononuclear cell infiltration, perivascular cuffing, and demyelination that was predominant in the lateral columns. In 1 patient, a retrovirus morphologically similar to HTLV-I on electron microscopy was isolated from spinal fluid. Our investigations show that endemic tropical spastic paraparesis in Jamaica is a retrovirus-associated myelopathy and that HTLV-I or an antigenically similar retrovirus is the causal agent.

Studies on activation variables in multiple sclerosis

The study aimed to evaluate the usefulness of some selected immune variables as markers of disease activation, progression and possible etiopathogenesis of multiple sclerosis (MS). Levels of neopterin, a factor known to be released from macrophages and monocytes at increased rates in cellular immune reactions were higher in cerebrospinal fluid (CSF) from patients with MS during exacerbations in comparison with remissions. The elevation in CSF during exacerbations was not reflected in serum. Expression of HLA class II antigens (DR) on activated T lymphocytes in CSF were encountered at elevated percentage in only 10% of patients with MS, against 81% of patients with acute aseptic meningoencephalitis (AM). In patients with AM, the DR expression on CSF T cells was found on both CD8+ and CD4+ cells. There was no correlation between percentage of DR+ T cells in CSF and disability, exacerbation/remission or recent onset of disease in patients with MS. Phenotypic characterization of mononuclear cells in CSF and peripheral blood revealed increased proportion of CD5+ cells in CSF compared to peripheral blood which in MS was not reflected by any changes in CD4+ or CD8+ cells, while in AM the increase of CD5+ cells in CSF was followed by increase of CD4+ cells. A population of CD5+, CD8-, CD4- cells might be postulated to occur in MS CSF. Levels of CD8+ cells in peripheral blood and CSF did not fluctuate in parallel with disease activity as measured as clinical exacerbation. OKB7+, OKM1+ and HLA-DR+ cells differed significantly between CSF and peripheral blood, indicative of a selective passage of cells into the central nervous system (CNS) - CSF compartment. Proliferating cells expressing transferrin receptors (OKT9) were generally few or absent in CSF of patients with MS. MS patients' bone marrow mononuclear cells showed higher spontaneous proliferation both in comparison with cells from bone marrow of control subjects and peripheral blood lymphocytes from MS patients. PHA response of bone marrow mononuclear cells from MS patients was also higher than that from controls. There was, however, no significant difference in proliferative response of peripheral blood lymphocytes between MS patients and controls. Seven of 11 MS patients showed morphological signs of activation in their bone marrow, without correlation to patients' clinical condition. Higher levels of undifferentiated or activated cells, measured as OKT10+ cells were found in peripheral blood of patients with MS compared to controls.(ABSTRACT TRUNCATED AT 400 WORDS)