Progressive multifocal leukoencephalopathy in an HTLV-I carrier.

This report describes a previously 28-year-old healthy woman, identified as an asymptomatic human T-lymphotropic virus type I (HTLV-I) carrier, who developed both progressive multifocal leukoencephalopathy (PML) and Pneumocystis jiroveci pneumonia. For diagnostic confirmation of PML, stereotactic brain biopsy demonstrated multiple demyelinating lesions with the presence of JC viral antigen. Intramuscular alpha-interferon therapy for 2 weeks brought considerable neurologic improvement. Three years later, the patient developed lymphoma-type of adult T-cell leukemia, suggesting that HTLV-I carrier might be one of the underlying diseases of PML.

Seroindeterminate HTLV-1 prevalence and characteristics in blood donors in Taiwan.

Human T-cell leukemia virus type 1 (HTLV-1) is commonly accepted as the cause of adult T-cell leukemia and tropical spastic paraparesis/HTLV-1-associated myelopathy. Screening of blood donors for HTLV-1 and HTLV-2 was implemented in Taiwan in February 1996. From February 1996 to December 1998, we investigated the seroprevalence of HTLV-1 in all unpaid blood donors in Taiwan. Of 2,578,238 donors in all 6 blood centers, 1793 (0.06%) were seropositive for HTLV-1, and 605 (0.023%) were indeterminate for HTLV-1. Among these indeterminate donors, 359 (59.3%) were male. The most common HTLV-1-indeterminate pattern by Western blot in our study was GD21 alone (34.6%) followed by p24 alone (7.8%), p53 alone (6.5%), and gp46 + GD21 (6.0%). That GD21 pattern was found in 59.6% of indeterminate results in this study suggested that the majority of nonspecific enzyme immunoassay reactions were probably precipitated by viral envelop glycoprotein GD21.

Comparison of four HTLV-I and HTLV-I + II ELISAs.

BACKGROUND: Various countries require blood donor screening using assays applying specific HTLV-I and HTLV-II antigens. We evaluated the sensitivity and specificity of 4 anti-HTLV-I + II ELISAs (Abbott, Murex, Organon Teknika and Ortho). METHODS: Panel A consisted of HTLV-I-positive individuals (n = 41), panel B of Mixed Titer Performance Panel 204 (Boston Biomedica Inc. panels C and D of dilution series from HTLV-I-positive (n= 30) and HTLV-II-positive (n =20) individuals and panel E of sera from first-time blood donors (n = 1,055). RESULTS: In HTLV-I- and -II-positive samples, a sensitivity of 100% could be observed in all 4 ELISAs. In diluted HTLV-I- and -II-positive samples, probit analysis revealed that the Murex assay had the highest analytical sensitivity, followed by the ELISAs from Ortho, Abbott and Organon Teknika. In specimens from first-time donors, a specificity of 100% was observed in ELISAs from Murex, Organon Teknika and Ortho, and of 99.7% in the assay from Abbott. CONCLUSION: The 4 anti-HTLV-I + II ELISAs studied were appropriate as screening tests.

[Virological studies on HTLV-1 carrier pregnant women].

Vertical transmission of HTLV-1 (human T-cell leukemia virus type 1) from HTLV-1 carrier mothers to their newborns has been reported with transmission rates, ranging from 6% to 78%. This study was undertaken to identify the high risk group of vertical transmission by detecting viral antigen in cultured lymphocytes and provirus obtained from carrier mothers. Subjects of this study were 70 HTLV-1 carrier mothers who attended the department of obstetrics and gynecology of hospital located in the Kanto area (ATL non endemic area). HTLV-1 antigen was detected in 40 out of 55 (72.7%) in peripheral blood lymphocytes of carrier mothers. HTLV-1 antigen was detected in 2 out of 40 (5.0%) in cord blood lymphocytes of infants born of carrier mothers. These two infants were born from carrier mothers with positive antigen detection study. It seems that carrier mothers whose peripheral lymphocytes are positive for antigen expression by culture are a high risk group for vertical transmission.

Prevalence of human T-cell leukemia virus type 1 (HTLV-I) in family members of adult T-cell leukemia (ATL) patients in non-ATL-endemic Hokkaido of Japan.

Family members of patients with adult T-cell leukemia (ATL) in non-ATL-endemic Hokkaido, the northernmost part of Japan, were assessed for the prevalence of HTLV-I infection. Immunofluorescence assay showed that 53 out of 133 (39.8%) healthy family members of 23 ATL patients were positive for antibodies to HTLV-I. When general inhabitants in Hokkaido were examined, 3 out of 18 (16.7%) family members of 5 seropositive healthy persons had HTLV-I antibodies. The overall seropositivity in Hokkaido was 0.7%. Of 26 family members of 6 patients with non-T-cell leukemia seroconverted by blood transfusion, none (0%) was seropositive.

Identification of a type-specific protein that differentiates serologically between human T cell lymphotropic virus types I and II.

The 24-kDa band formed when sera of humans infected with human T cell lymphotropic virus type I (HTLV-1) were reacted with HTLV-I lysates in conventional Western blot (WB) assays was found to be composed of two immunologically unrelated proteins of 24- and 23-kDa. p24, but not p23, carries epitopes shared by the major core proteins of the other known transactivating C-type retroviruses. p23 is unrelated immunologically to the env and tax HTLV-I products but partly cross-reacts with HTLV-I p19. All HTLV-I and simian T cell leukemia virus type I sera tested reacted with p23. Reactivity with p23 was seen with some HTLV-I sera that did not react or reacted weakly with HTLV-I p24. No reactivity with p23 was seen among the 51 human HTLV-II sera tested nor among a large panel of control sera. Because of its type-specificity and strong immunogenicity, p23 provides a reliable serologic marker for the diagnosis of HTLV-I infection and for distinguishing between HTLV-I and -II.

Isotypic and IgG subclass restriction of the humoral immune responses to human T-lymphotropic virus type-I.

We have investigated the isotypic and IgG subclass profile of the antibody response to HTLV-I structural proteins (gag and env) in patients with HTLV-I-associated myelopathy (HAM; n = 20), adult T-cell leukemia (ATL; n = 15), and HTLV-I-positive asymptomatic carriers (ASY; n = 21). IgG, IgM, and IgA were the predominant antibody responses in all HTLV-I-infected individuals; minimal IgE response was detectable in the HAM and ATL groups. Among the IgG subclasses, IgG1 was the most predominant antibody detected in responses to HTLV-I antigens, followed by IgG3 and IgG2; IgG4 could not be detected in any patient group. Levels of both IgG1 and IgG3 were significantly higher in patients with HAM, when compared to ATL and ASY (P < 0.01 for both comparisons). In addition, Ig isotypes and IgG subclass antibody in patient sera reactive with purified viral proteins and several immunodominant epitopes, represented by synthetic peptides, Gag-1a102-117, Env-1(191-214), Env-5(242-257), and recombinant proteins, MTA-1(162-209) and r21e303-440, were examined to delineate specific epitopes responsible for inducing the host immune responses of each isotype and subclass to the structural proteins of HTLV-I. IgG, IgM, and IgA responses were directed against both the gag and env gene products. Among IgG subclasses, the IgG1 and IgG3 responses were directed against both the gag (p53, p24, p19, and Gag-1a) and env (recombinant MTA-1, r21e, and synthetic Env-1, Env-5) proteins; IgG2 responses were mainly restricted to gag proteins. The frequency profile of HTLV-I-specific antigen recognition in all four IgG subclasses were similar in all of the clinical groups. These results further define the fine specificity of anti-HTLV-I immune reaction for understanding the mechanism of pathogenesis in these individuals and suggest that factors other than the humoral immune responses may be associated with the clinical manifestation of the disease.

Discrimination of human T-lymphotropic virus type-I and type-II infections by synthetic peptides representing structural epitopes from the envelope glycoproteins.

Synthetic peptides representing the immunodominant structural motifs of the envelope region of human T-lymphotropic virus types I (HTLV-I) (Env-1(191-214) and Env-5(242-257)) and II (HTLV-II) (Env-20(85-102 and Env-2(187-209)) were used to develop an enzyme immunoassay that could discriminate between HTLV-I and HTLV-II. Serum specimens from individuals whose infections were confirmed and typed by means of the polymerase chain reaction (PCR) were used to determine the sensitivity and specificity of the new assay. When 73 PCR-confirmed HTLV-I specimens were tested with the HTLV-I peptides, the absorbance values for 71 (97.3%) were at least two times higher than the values obtained with the HTLV-II peptides; these samples thus were classified as HTLV-I. Two specimens reacted with all the peptides and, therefore, could not be typed. Conversely, when 59 PCR-confirmed HTLV-II specimens were tested with the HTLV-II peptides, 55 (93%) produced high absorbance values and were typed as HTLV-II; 4 specimens could not be typed. None of the specimens was incorrectly typed; hence, the specificity of this assay was 100%. When this assay was compared with other HTLV immunoassays, the degrees of sensitivity and specificity were similar. The main advantage of this new assay is that synthetic peptides representing variant sequences can easily be added as new variant HTLV strains are identified.

HTLV-1 sequences in lymphocytes of a patient with non-tropical spastic tetraparesis and her asymptomatic husband.

We describe a 65-year-old woman born and living in Northern Italy affected by non tropical spastic tetraparesis and her asymptomatic husband presenting HTLV-1 sequences in their lymphocytes detected by polymerase chain reaction (PCR). We discuss the significance of the case and the mechanism involved in HTLV-1 infection and the relationship with neurological disorders, stressing that this case is the first reported in Italy.

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.

Detection of HTLV-I antigen in peripheral and cord blood lymphocytes from carrier mothers.

Vertical transmission of human T-cell lymphotropic virus type-I (HTLV-I) from an antibody-positive carrier mother to her infant has been reported, but it is not clear when and by what route such transmission occurs. Peripheral blood and cord blood lymphocytes from 40 antibody-positive carrier mothers were cultured for 2 months and HTLV-I antigen was sought by indirect immunofluorescence. Viral antigen was detected in 28 (70%) samples of peripheral blood lymphocytes and in 2 of cord blood lymphocytes, both from mothers positive for antigen in peripheral blood. From these data it is estimated that transplacental infection occurs at a rate of about 7%.

Novel and sensitive enzyme immunoassay (immune-complex-transfer enzyme immunoassay) for antihuman T cell leukemia virus type 1 IgG in human serum using recombinant gag-env hybrid protein as antigen.

A novel and sensitive enzyme immunoassay (immune-complex-transfer enzyme immunoassay) for antihuman T cell leukemia virus type 1 IgG (anti-HTLV-1 IgG) in human serum using recombinant gag(14-139)-env-(197-295) hybrid protein is described. Anti-HTLV-1 IgG in test serum was reacted with dinitrophenyl biotinyl bovine serum albumin-recombinant gag-env hybrid protein conjugate. The complex formed was trapped onto polystyrene balls coated with affinity-purified antidinitrophenyl group IgG. After washing to eliminate nonspecific IgG in the test serum, the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine and transferred to polystyrene balls coated with streptavidin. After washing, anti-HTLV-1 IgG in the complex trapped onto the streptavidin-coated polystyrene balls was reacted with antihuman IgG gamma-chain Fab'-peroxidase conjugate. Peroxidase activity bound to the streptavidin-coated polystyrene balls was assayed by fluorometry. By transfer of the complex, the nonspecific binding of nonspecific human IgG was considerably reduced, and the detection limit of anti-HTLV-1 IgG in serum was lowered 30-300-fold compared with that by Western blotting, gelatin particle agglutination, and the conventional enzyme immunoassay, in which a recombinant gag-env hybrid protein-coated polystyrene ball was incubated with test serum and, after washing, with antihuman IgG gamma-chain Fab'-peroxidase conjugate. Usefulness of the immune-complex-transfer enzyme immunoassay was demonstrated using 271 serum samples.