Familial cases of HTLV-I-associated myelopathy

Early Onset of HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) and Adult T-cell Leukemia/Lymphoma (ATL): Systematic Search and Review

Human T-cell lymphotropic virus type 1 (HTLV-1) is endemic in some regions and its vertical transmission occurs mainly through breastfeeding. About 10% of carriers develop associated diseases including HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), adult T-cell leukemia/lymphoma (ATL) and infectious dermatitis associated with HTLV-1 (IDH). We searched for available case reports of early-onset HAM/TSP and ATL to evaluate demographic and disease aspects in infantile-juvenile patients. In the reviewed literature, 27 HAM/TSP and 31 ATL cases were found. In almost all of them, the most likely route of transmission was through breastfeeding. ATL is rarely reported, notwithstanding it may be underestimated because T-cell lymphomas are not investigated for HTLV-1 infection in this age group. IDH was frequently associated with HAM/TSP. The investigation of HTLV-1 infection in pregnant women is an important matter of public health and should be mandatory in endemic countries.

Family Aggregation of Human T-Lymphotropic Virus 1-Associated Diseases: A Systematic Review

Human T-lymphotropic virus 1 (HTLV-1) is a retrovirus that produces a persistent infection. Two transmission routes (from mother to child and via sexual intercourse) favor familial clustering of HTLV-1. It is yet unknown why most HTLV-1 carriers remain asymptomatic while about 10% of them develop complications. HTLV-1 associated diseases were originally described as sporadic entities, but familial presentations have been reported. To explore what is known about family aggregation of HTLV-1-associated diseases we undertook a systematic review. We aimed at answering whether, when, and where family aggregation of HTLV-1-associated diseases was reported, which relatives were affected and which hypotheses were proposed to explain aggregation. We searched MEDLINE, abstract books of HTLV conferences and reference lists of selected papers. Search terms used referred to HTLV-1 infection, and HTLV-1-associated diseases, and family studies. HTLV-1-associated diseases considered are adult T-cell leukemia/lymphoma (ATLL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV-1-associated uveitis, and infective dermatitis. Seventy-four records reported HTLV-1-associated diseases in more than one member of the same family and were included. Most reports came from HTLV-1-endemic countries, mainly Japan (n = 30) and Brazil (n = 10). These reports described a total of 270 families in which more than one relative had HTLV-1-associated diseases. In most families, different family members suffered from the same disease (n = 223). The diseases most frequently reported were ATLL (115 families) and HAM/TSP (102 families). Most families (n = 144) included two to four affected individuals. The proportion of ATLL patients with family history of ATLL ranged from 2 to 26%. The proportion of HAM/TSP patients with family history of HAM/TSP ranged from 1 to 48%. The predominant cluster types for ATLL were clusters of siblings and parent-child pairs and for HAM/TSP, an affected parent with one or more affected children. The evidence in the literature, although weak, does suggest that HTLV-1-associated diseases sometimes cluster in families. Whether familial transmission of HTLV-1 is the only determining factor, or whether other factors are also involved, needs further research.

On the etiology of tropical spastic paraparesis and human T-cell lymphotropic virus-I-associated myelopathy

The purpose of this review is to present some concepts on the etiology of tropical spastic paraparesis or human T-cell lymphotropic virus-I (HTLV-I)-associated myelopathy (TSP/HAM). The large number of syndromes that have been associated with HTLV-I (60 to date), the existence of TSP/HAM cases associated with other retroviruses (human immunodeficiency virus-2 [HIV-2], HTLV-II), the existence of many TSPs without HTLV-I, and the evidence of clear epidemiologic contradictions in TSP/HAM indicate that the etiopathogenesis of TSP/HAM is not yet clear. Tropical spastic paraparesis/HAM affects patients of all human ethnic groups, but usually in well localized and relatively isolated geographic regions where HTLV-I has been endemic for a long time. Environmental factors and geographic locations appear to be critical factors. Because the neuropathology of TSP/HAM suggests a toxometabolic, rather than a viral cause, it is proposed that an intoxication similar to neurolathyrism could account for some of TSP/HAM cases, mainly in tropical and subtropical countries. If this were the case, HTLV-I could be a cofactor or act as a bystander. it is possible that co-infection with another agent is necessary to produce TSP/HAM and most of the syndromes associated with HTLV-I.

Transmission of human T cell leukemia virus type I to sheep: antibody profile and detection of viral DNA sequences

Lambs were inoculated intraperitoneally with either 1.8 x 10(7) live peripheral blood cells from an HTLV-I-infected person (five lambs) or with 8 x 10(7) live cells from the HTLV-I-producing cell lines MT-2 (four lambs) or C10 MJ (five lambs). Four control lambs were inoculated with minimal essential medium supplemented with fetal calf serum. The animals were monitored during a period of 24 months. Beginning at 5 to 12 months after inoculation, four of the five lambs inoculated with the fresh HTLV-I-infected peripheral blood cells began to develop detectable levels of antibodies to a recombinant HTLV-I gp21env antigen, as determined by an enzyme-linked immunoassay (ELISA). The anti-gp21 antibodies persisted for the remaining observation period. These antibodies were not detected in the sera from the other sheep. Absorption and blocking experiments demonstrated the specificity of the gp21 reactivity. This reactivity was also confirmed by Western blot (WB). With the exception of the serum of an MT-2-inoculated sheep that formed a weak band with p19 by WB, none of the sera of the four gp21-positive sheep or of the other experimental sheep reacted with other structural or regulatory HTLV-I proteins, as determined by ELISA, WB, and radioimmunoassay. PCR analyses demonstrated the presence of the HTLV-I provirus in peripheral blood leukocytes of the four sheep showing antibodies to gp21env. The remaining sheep were negative. PCR analyses failed to detect BLV sequences in any of the experimental sheep. None of the sheep showed clinical abnormalities during the observation period. The potential value of the sheep model for studying atypical virus-host interactions in infected people is discussed.

Nucleotide sequences of human T-lymphotropic virus type I (HTLV-I) from a family cluster with tropical spastic paraparesis/HTLV-I-associated myelopathy

We describe nucleotide sequences of human T-lymphotropic virus type I (HTLV-I) proviruses from three symptomatic family members with tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) from Tumaco, Colombia. Polymerase chain reaction was used to clone the U3 region, envelope and tax/rex genes of these HTLV-I proviruses from fresh peripheral blood lymphocytes. Sequences in U3, env and tax/rex showed 96.9-99.5% conservation when compared with sequences from HTLV-I clone ATK, and 96.6-100% when compared with each other. The range of sequence divergence within the family was similar to that described between unrelated TSP/HAM patients of the same geographical origin. Certain mutations were present in all three family members, supporting a geographic and/or familial segregation of mutations.

Contralateral early blink reflex in patients with HTLV-I associated myelopathy/tropical spastic paraparesis

Thirty-two Japanese patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) were studied by means of the electrically elicited blink reflex and three responses (R1, R2, R3) were registered. 69% of the patients displayed a uni- or bilateral crossed R1 response (R1k) as compared to 11% in the control group. A positive correlation between R1k and an exaggerated jaw jerk reflex was found in the patients. Central abnormalities of the nervous system with diminished presynaptic inhibition acting in the interneuronal input of the brainstem of HAM/TSP patients was the most likely cause. It could lead to the unmasking of crossed trigemino-facial pathway reflex which is present in the normal population from birth. These results strongly support the supraspinal involvement of the central nervous system (CNS) in HAM/TSP more than usually thought.

Six Colombian patients with adult T-cell leukemia/lymphoma

Six Colombian patients with adult T-cell leukemia/lymphoma (ATL) are presented. The clinical and hematological features, the familial clusters of human T lymphotropic virus type 1 (HTLV-I) carriers and the prognoses of the Colombian ATL patients were similar to those previously reported for Japanese ATL patients. The only difference was the mean age of onset, which was more than 20 years younger than in Japanese patients. Three patients with ATL were suffering from strongyloidiasis. In one patient it was suggested that ATL developed after horizontal transmission from his wife. In addition, there was a familial case of ATL and HAM/TSP. It seems that in some areas of Colombia, not only HTLV-I infection and HAM/TSP but also ATL are highly endemic.

Considerations on HAM/TSP. Rediscovering Tumaco

Considerations are made on the role of HTLV-I in the etiopathogeny of HAM/TSP. Neuroepidemiologic data reported in the literature are revisited for this purpose. Among results of this evaluation it is pointed-out that the Okinawan Community of Brazil presents ethnographic and demographic characteristics which are ideal for designing new studies. For instance, analyses on HTLV-I and on HAM/TSP in face of the cohort of such community classified according to time and direction of the migration (Japan-Brazil and vice-versa), will ensure promising results for the understanding of etipathogeny of HAM/TSP. They can also be paths towards clarifying the simultaneous generating, of geographical foci of the disease distant one the other, as that of Tumaco and that of south Japan.

Comparative biological responses of rabbits infected with human T-lymphotropic virus type I isolates from patients with lymphoproliferative and neurodegenerative disease

An experimental rabbit model was used to determine host responses to infection by various human T-lymphotropic virus type-I (HTLV-I) strains. Seven groups of 4 to 5 rabbits each were inoculated with lethally-irradiated HTLV-I-infected cell lines derived from patients with adult T-cell leukemia/lymphoma or from patients with HTLV-I-associated myelopathy. Four separate control groups of 2 rabbits each were inoculated with similarly prepared HTLV-I-negative cells derived from rabbits or humans. Anti-viral antibody responses were assessed by immunoblot assay and hematologic parameters were measured using automated cell counters and cytologic staining. The virologic status of challenged rabbits was determined by co-culture and HTLV-I antigen capture assay, as well as by polymerase chain reaction (PCR) amplification of HTLV-I DNA from peripheral blood mononuclear cells (PBMC) or tissues. The HTLV-I inocula could be separated into groups based upon their infectivity to rabbits: highly infectious strains elicited intense serologic responses and were detected frequently in tissues by antigen and PCR assays, while other strains were moderately to poorly infectious, induced weak antibody responses and were infrequently detected by antigen and PCR assays. Overall, PBMC appeared to have the greatest quantity of HTLV-I containing cells, while bone marrow was a poor source of virus. No clinical or hematologic abnormalities were evident during the 24-week course of infection. Taken together, our results suggest there is heterogeneity in the biological response to HTLV-I infection which is, in part, dependent on the infecting strain of virus.

Characterization of two human lymphoid cell lines producing human T-lymphotropic virus type I (HTLV-I) isolated from patients with HTLV-I-associated myelopathy or encephalopathy

Two cell lines, CNS-5 and CNS-6, were established by cocultivation of sedimented cells in cerebrospinal fluid (CSF) from two anti-human T-lymphotropic virus type I (HTLV-I) antibody-positive male patients with encephalopathy and HTLV-I-associated myelopathy, respectively, with peripheral blood mononuclear cells from a healthy seronegative female. These cell lines, possessing a normal female karyotype, revealed similar characteristics as follows; they expressed HTLV-I-related antigens, they produced C-type retrovirus particles, HTLV-I provirus genomes were integrated into their DNAs, and they had CD4+ activated T-cell markers. In addition, immunocytochemical and immunoelectron microscopic studies showed peculiar immunoreactivity of these cell lines with anti-alpha/beta T-cell antigen receptor (TCR) antibodies; beta Fl, defining beta chain epitope, was only positive in the perinuclear spaces and rough endoplasmic reticulum in some cells, and WT31, recognizing alpha/beta framework, was mostly negative, while CD3 was expressed in the majority of the cells. These facts indicate that HTLV-I-infected cells were present in CSF of these two patients, and suggest that neurological disorders associated with HTLV-I may not be restricted to myelopathy and may include brain abnormalities.

Familial adult T-cell leukemia/lymphoma

Clinical and laboratory data are described for two siblings who both developed adult T-cell leukemia/lymphoma resulting from infection by human T lymphotropic virus type I (HTLV-I). These findings suggest that genetic factors or virus-specific factors may determine which HTLV-I-infected individuals will develop leukemia.

A cluster of HTLV-1 associated tropical spastic paraparesis in Equateur (Zaire): ethnic and familial distribution

In Lisala, Equateur province, Zaire, 25 patients from 21 pedigrees were identified with human T-lymphotropic virus type 1 (HTLV-1) associated tropical spastic paraparesis (TSP). In the 10 (48%) pedigrees with additional genuine TSP cases established mainly by history, seven of 10 patients' mothers, no fathers or spouses, one of 59 surviving offspring, five of 105 siblings, and six other close blood relatives had TSP. A child may develop TSP before its mother. Three familial cases were in paternal relatives only. In total, 39 cases (11 men, 28 women) were identified in this population of about 50,000. Half were in the Mundunga minority of less than or equal to 10% (p less than 0.001). The data suggest maternal transmission of HTLV-1 and enhanced TSP susceptibility in those infected due to familial, probably genetic factors.

Characterization of HTLV-I isolates and T lymphoid cell lines derived from French West Indian patients with tropical spastic paraparesis

Lymphoid cell lines derived from the peripheral blood of French West Indian patients with HTLV-I sero-positive Tropical Spastic Paraparesis and HTLV-I isolates were characterized. While patients' peripheral blood lymphocytes did not express detectable HTLV-I antigens when uncultured, they did so after short-term culture. Established cell lines were of T-cell lineage: CD2+, CD3+, CD4+, CD7+, WT31+ with activated T-cell markers CD25+, DR+ and a clonal rearrangement of the beta and gamma genes of the T-cell receptor. HTLV-I antigens were detected in cell lines by indirect immunofluorescence, Western blot and radio-immunoprecipitation assays. After 4 months in culture, low levels of Mg2+ dependent reverse transcriptase activity were detected and electron microscopy revealed numerous type-C retroviral particles similar to HTLV-I virions. Western blot and radio-immunoprecipitation analysis of purified viruses revealed gp46, p24, p19 and Pr53gag proteins similar to those detected in HUT 102 and MT2 cell lines. Deep analysis of env-coded precursor of one TSP versus ATL isolates revealed minor differences in their molecular weights. Southern blot analysis using 32P HTLV-I env gene as a probe showed the presence of HTLV-I proviral fragments clonally integrated into the genome of the cell lines. Our data suggest that HTLV-I isolated from Tropical Spastic Paraparesis does not differ significantly from the leukemogenic prototypes. Does HTLV-I induce either acute lymphoproliferative diseases or chronic neuromyelopathies depending upon as yet unknown co-factors? This question remains to be determined.

Inflammatory lesions of peripheral nerve in a patient with human T-lymphotropic virus type I--associated myelopathy

In a patient with tropical spastic paraparesis associated with a positive titer for human T-lymphotropic virus type I, electrophysiological study detected a mixed, axonal and demyelinating, multifocal neuropathy. Perineural and perivascular infiltrates, moderate axon loss, wallerian degeneration, and demyelinating lesions of isolated fibers were present in the nerve biopsy specimen. These inflammatory lesions resembled those found in the central nervous system of patients with tropical spastic paraparesis.