Interviews of individuals diagnosed as anti-human immunodeficiency virus-positive through the screening of blood donations in the Paris area to 1994: reflections on the selection of blood donors

BACKGROUND: One of the aims of the medical interview routinely preceding each blood donation is the identification of individuals with a risk factor for infection with the human immunodeficiency virus (HIV). STUDY DESIGN and METHODS: Interviews were performed with individuals diagnosed as being seropositive for HIV through the systematic biologic screening of blood donations in the Paris area to establish, first, the circumstances allowing HIV-seropositive individuals to pass through the predonation medical interview and, second, the motivation of these individuals as blood donors. Risk factors of 30 HIV-infected donors identified between 1991 and 1994 were determined. RESULTS: When asked whether they recognized the eventual risk to recipients of donated blood, 14 (47%) of 30 answered positively. Fifteen (50%) admitted having given their blood to determine their HIV status. CONCLUSION: These individuals did not exclude themselves from blood donation and probably hid their risk factor(s) at the predonation interview in order to be accepted as blood donors.     

Human T-lymphotropic virus type I among blood donors from Guadeloupe: donation, demographic, and biologic characteristics

BACKGROUND: Epidemiologic data on human T-lymphotropic virus type I (HTLV-I) in Guadeloupe (French West Indies) are scant. STUDY DESIGN AND METHODS: From January 1989 to December 1996, 59,426 blood donors were screened by enzyme immunoassay for antibodies to HTLV-I. All repeatedly reactive samples were confirmed by Western blot. Temporal trends in HTLV-I seropositivity rates were examined during the study period. A multivariate analysis of donation, demographic, and biologic characteristics was performed. RESULTS: Of the screened blood donors, 195 were confirmed as seropositive, for an overall prevalence of 0.33 percent (95% CI 0.28-0.38). A marked decrease in overall HTLV-I prevalence with time (from 0.47% in 1989 to 0.13% in 1996) was observed, which can be explained mainly by the decreasing percentage of recruited new donors during the study period. Four independent risk factors for HTLV-I were identified: new donor status (odds ratio [OR] 12.5), female sex (OR 1.7), increasing age (30-39 years: OR, 2.4; 40-49 years: OR, 3.7; >50 years: OR 6.6), and positive antibodies to hepatitis B virus core antigen (OR, 1.7). Selection of specific locations for blood collection was inversely associated with HTLV-I (OR 0.5). CONCLUSION: New donor status, advancing age, female sex, and positivity for hepatitis B virus core antibodies were the major factors associated with HTLV-I infection in Guadeloupe.     

Seroindeterminate patterns and seroconversions to human T-lymphotropic virus type I positivity in blood donors from Martinique, French West Indies

BACKGROUND: Screening for human T-lymphotropic virus type I (HTLV-I) antibodies in volunteer blood donors has been systematic in the French West Indies since 1989. Western blot-indeterminate results are commonly obtained. The significance of these indeterminate serologic patterns in HTLV-I-endemic areas is still unclear. STUDY DESIGN AND METHODS: During a 2-year period, 9759 blood donors were tested for HTLV-I antibodies. The epidemiologic features of HTLV-I-seropositive, -seroindeterminate, and -seronegative donors were compared. A lookback investigation was performed for the HTLV-I-seropositive donors, and the HTLV-I-seroindeterminate individuals were followed up. RESULTS: Thirty-nine donors (0.4%) were HTLV-I seropositive and 49 (0.5%) were seroindeterminate. The age and sex ratio characteristics of the seroindeterminate donors are divergent from those of the HTLV-I-seropositive group and are more like those of the seronegative population. However, during the study period, three cases of seroconversion after an initial seroindeterminate profile were reported. Two cases were detected through follow-up of 38 HTLV-I-seroindeterminate donors over a mean of 8 months (2-24 months). The third seroconverter belonged to the HTLV-I-seropositive group and was identified through lookback investigation. This case is atypical, with p19 reactivity for several months before HTLV-I seropositivity. CONCLUSION: These findings indicate that, although HTLV-I-seroindeterminate donors mainly are HTLV-I-noninfected, the rate of seroconversion in a repeat blood donor population from an endemic region must be taken into consideration. Moreover, the case of delayed seroconversion observed in this study suggests the difficulty of counseling seroindeterminate blood donors in endemic regions.     

Evaluation of HTLV-I removal by filtration of blood cell components in a routine setting

BACKGROUND: WBC depletion by filtration may prevent the transmission of HTLV-I, which requires cell-to-cell contact. The removal of HTLV-I-infected cells in routinely filtered blood cell components was measured. STUDY DESIGN AND METHODS: The study was conducted in Martinique where systematic screening for HTLV-I and -II and universal leukoreduction are mandatory. HTLV-I was quantified by use of real-time PCR in 8 RBC units and 4 PLT concentrates before and after filtration. HTLV-I proviral load in PBMNCs was determined in five of the eight HTLV-I-infected blood donors. RESULTS: The amount of MNC-associated HTLV-I DNA in RBC units before filtration was 21 x 10(6)+/- 29 x 10(6) copies (mean +/- SD). HTLV-I was detected in 4 of 8 RBC units after filtration, with a number of copies in the MNC fraction ranging from 20 to 140, following a 4.9 to 5.8 log reduction. Flow cytometry analysis performed in 2 of the filtered RBC units containing detectable HTLV-I showed suboptimal and out-of-range leukoreduction (0.56 x 10(6) and 1.22 x 10(6) residual WBCs). HTLV was not detected in filtered RBCs from the blood donor with the highest percentage of HTLV-I-infected PBMCs (9%). CONCLUSION: This study confirms that HTLV-I-infected cells can be detected in filtered blood cell components and shows that optimal leukoreduction is critical for HTLV-I removal.     

Results of 1-year screening of donors in The Netherlands for human T− lymphotropic virus (HTLV) type I: significance of Western blot patterns for confirmation of HTLV infection

BACKGROUND: Between January 1993 and January 1994, Dutch blood banks screened approximately 674,000 volunteer donors for the presence of antibodies to human T-lymphotropic virus type I (HTLV-I). STUDY DESIGN AND METHODS: Confirmatory testing was performed on samples from 870 different anti-HTLV-I-reactive donors (0.13% of the total tested). RESULTS: According to the authors' Western blot (WB) interpretation criteria, 15 (0.002%) donors tested HTLV-I-positive in the WB; 201 tested negative, and 654 (75% of donors reacting on enzyme-linked immunosorbent assay) tested indeterminate. Fresh samples from 234 of 870 anti-HTLV-reactive donors were tested for HTLV-I and type II (HTLV- II) DNA by polymerase chain reaction: all 15 WB-positive donors tested positive for HTLV-I DNA; 206 WB-indeterminate and 13 WB-negative donors tested negative for HTLV-I and -II DNA. Application of the manufacturer's (World Health Organization-based) guidelines for WB interpretation would have resulted in the misclassification of 48 (23%) of 206 polymerase chain reaction-negative donors as HTLV-I/II-positive. Risk factors were present in 14 of 15 HTLV-I-infected donors: 8 had a partner from an HTLV-I-endemic area, 4 were from HTLV-I-endemic countries, and 2 had received blood transfusions. CONCLUSION: HTLV-I and -II infection is rare among Dutch blood donors. HTLV screening will prevent few cases of HTLV-related disease, but it will prevent a further spread of the virus by transfusion. In a low-risk population, conservative guidelines for WB interpretation unnecessarily generate an excess of false-positive results.     

Human T-lymphotropic virus type I and type II infections and correlation with risk factors in blood donors from Sao Paulo, Brazil

BACKGROUND: Little is known about the prevalence of and risk factors for human T-lymphotropic virus type I and type II (HTLV-I, HTLV-II) infections in Brazil. STUDY DESIGN AND METHODS: Sera from 17,063 healthy Brazilian donors were screened by enzyme-linked immunosorbent assay for antibody to HTLV-I/II between August 1991 and July 1993. Repeatedly reactive samples were confirmed by Western blot, and discrimination between HTLV-I and HTLV-II was made by polymerase chain reaction or synthetic peptide enzyme-linked immunosorbent assay. A univariate analysis was performed on demographic and serologic data. RESULTS: HTLV-I infection was demonstrated in 83 percent of the 30 donors with reactive serologic tests (0.15% of the total tested [17,063]; 95% CI, 0.09-0.20) and HTLV-II infection in 17 percent (0.03% of the total tested [17,063]; 95% CI, 0.01-0.05). HTLV-I-positive donors were more likely than reference groups to be of Asian ethnicity (odds ratio [OR] 15.1; reference group: whites), more than 50 years old (OR 4.2; reference group: 20–29 years old), and positive for antibody to hepatitis C virus (anti-HCV) (OR 21.8) or to hepatitis B core (antigen) (anti-HBc) (OR 5.7). HTLV-II showed a significant association with anti-HCV (OR 75.2) and anti-HBc (OR 21.8). Eleven of the 25 HTLV-I- positive donors were counseled. Family origin in endemic areas of Japan (n = 4), prior blood transfusion (n = 3), or sexual contact with prostitutes (n = 1) were the risk factors reported by 8 donors. In 3 white men, no risk factors could be identified. CONCLUSION: Both HTLV-I and HTLV-II occur among Brazilian blood donors. HTLV-I is associated with Asian ethnicity, greater age, and the presence of anti-HCV and anti-HBc. Three HTLV-I-positive donors had a history of blood transfusion, which emphasizes the need for HTLV-I/II screening in Brazil.     

Adult T-cell leukemia/lymphoma in the Middle East: first report of two cases from Lebanon

BACKGROUND: Adult T-cell leukemia/lymphoma (ATL) is an aggressive lymphoproliferative disorder caused by human T-cell leukemia virus type I (HTLV-I). HTLV-I is endemic in southern Japan, the Caribbean, Central and South America, certain areas of Africa, and the southeastern United States. In the Middle East, North East Iran, particularly the region of Mashhad, has been recognized as an endemic region.
CASE REPORTS: In this report, the first two cases of ATL diagnosed in Lebanon are described. The first patient of Lebanese origin presented with acute ATL. The second patient of Romanian origin developed acute ATL in early relapse after autologous transplantation for ATL. Both patients had lymphocytosis, severe hypercalcemia, and CD25+ T-cell immunophenotype on peripheral blood. In both patients, HTLV-I serology was positive by enzyme-linked immunosorbent assay and confirmed by Western blot and HTLV-I oncoprotein Tax expression was documented in the leukemic cells. Upon screening, seven direct family members of the first patient were HTLV-I positive; four of them were regular blood donors.
CONCLUSIONS: Screening blood donors for HTLV-I seropositivity is not currently performed in Lebanon. A large screening study in Lebanon is needed to confirm whether South Lebanon is a new endemic region for HTLV-I infection and to recommend mandatory screening of blood donors for HTLV-I infection.     

Human T-cell lymphotropic virus type I and II in transfusion medicine.

As a consequence of migrating populations, IV drug use and, to a lesser extent, blood transfusions, endemic HTLV-I and HTLV-II infections have spread to nonendemic geographic regions. Although the risk that a person infected with HTLV-I will develop significant disease--even over a lifetime--is estimated to be relatively low, our awareness of the serious diseases associated with other retroviruses requires a cautious approach to blood transfusion. Reports from Japan and the United States indicate that programs testing donated blood and excluding units with HTLV-I antibodies have been highly successful in interrupting the spread of HTLV-I by transfusions. One unanticipated outcome of testing large numbers of people in the United States for HTLV-I antibodies has been recognition of the relatively high prevalence of HTLV-II infection, particularly among IV drug users. The long-term effects of HTLV-II infection are also unknown. Until the natural history and clinical consequences of HTLV-II infection are clearly understood, it is only prudent that blood donated by persons identified to be HTLV-II carriers also be excluded.     

The prevalence of antibody to HTLV-I/II in United States plasma donors and in United States and French hemophiliacs

Antibody to HTLV-I/II was detected in 19 (0.3%) of 6286 plasma donors from five regions of the United States (US). This seroprevalence rate is approximately 10 times that in whole blood donors. The regional distribution of infection was as follows: Southwest, 0.68 percent; Southeast, 0.45 percent; Midwest, 0.28 percent; Northwest, 0.1 percent; and Northeast, 0.0 percent. Rates of HTLV-I/II infection in blacks (0.74%) and Hispanics (0.66%) were higher (both, p less than 0.001) than those in whites (0.08%). All 19 infected units were donated by subjects aged 30 or older, even though 52.9 percent of the donations came from persons less than 30 years old. Equal rates of HTLV-I/II infection were found in men (0.31%) and women (0.29%). No HTLV-I/II antibody was detected in 154 French and 25 US hemophiliacs who were transfused regularly with noninactivated plasma or its derivatives. This suggests that the transfusion of HTLV-I/II-seropositive plasma products does not transmit the viral infection.     

Quick detection of Leishmania in peripheral blood by flow cytometry. Is prestorage leucodepletion necessary for leishmaniasis prevention in endemic areas?

Leishmaniasis is a serious health problem in various endemic areas. There are reports that the parasite can be transmitted via blood transfusions. We studied the clinical utility of flow cytometry for the screening of blood donors in an endemic area in Greece. Samples from 2000 blood donors from the area of Lasithi, Crete, Greece were examined by flow cytometry after labelling with a polyclonal anti-leishmania antibody conjugated with fluorescein-isothiocyanate derived from infected canines in the area. The same blood samples were simultaneously examined for serum anti-leishmania antibodies, May-Grünwald staining of peripheral blood smears and polymerase chain reaction (PCR) in buffy coat to the minicircle of kinetoplastic DNA. Direct sequencing of the PCR-amplified area helped discriminate leishmania species. Flow cytometry detected 33 cases with parasites in the peripheral blood leucocytes (1.65%), which were confirmed by PCR. One PCR-positive case was negative by flow cytometry. After prestorage leucodepletion, no sample was positive by PCR. Anti-leishmania antibodies were positive in 304 (15%) cases. Flow cytometry was found to be a sensitive and rapid method of detecting leishmania in peripheral blood samples. Leucodepletion effectively reduces the detection of the parasite, thus minimizing the potential risk of leishmania transmission through blood transfusions in endemic areas.     

Transfusion-associated transmission of human T-lymphotropic virus types I and II: experience of a regional blood center

During a 22-month period, 78,000 blood donors were screened for human T- lymphotropic virus types I and II (HTLV-I/II) at Belle Bonfils Memorial Blood Center (Denver, Colorado). Positive donors and the living recipients of their previously donated blood components were evaluated for risk factors and symptoms related to HTLV-I infection, were screened by enzyme immunoassay, confirmed by Western blot for HTLV- I/II, and subsequently tested by polymerase chain reaction and peptide enzyme immunoassay to distinguish between HTLV-I and -II infection. Six seropositive blood donors (0.008%) were identified; four were typed as having HTLV-I infection and two as having HTLV-II. Of 18 living recipients of components from seropositive donors, none had risk factors for HTLV-I infection prior to transfusion and none had signs or symptoms of HTLV-I infection at follow-up. The mean time from transfusion to testing was 6.4 years. Seven recipients of HTLV-I- infected components were HTLV seropositive; all were typed as having HTLV-I. A possible case of posttransfusion HTLV-I-associated myelopathy was identified in one patient who died before complete evaluation. One possible case of transfusion-associated HTLV-II was identified. These data further support the continued screening of blood donors for HTLV- I/II.     

Absence of human T-lymphotropic virus type I tax sequences in a population of normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study

BACKGROUND: It was reported recently that sequences corresponding to the human T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripheral blood mononuclear cells from 8 to 11 percent of healthy blood donors without detectable antibodies to HTLV-I. A multicenter blind study was conducted to determine if these results could be independently confirmed. STUDY DESIGN AND METHODS: Specimens were collected from 100 anti-HTLV-I-negative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positive individuals. All samples were coded and distributed to each of four independent testing laboratories for polymerase chain reaction analysis to detect sequences of the HTLV-I or HTLV-II tax gene, using detailed procedures specified by the laboratory reporting the original observation. Each laboratory also tested a dilution panel of a plasmid containing HTLV-I tax to determine the analytical sensitivity of the procedure. RESULTS: The analytical sensitivity of the screening methods permitted detection of as few as 1 to 10 copies of the tax gene. However, HTLV-I tax sequences could not be detected in any of the anti-HTLV-I-negative blood donors at more than one test site. CONCLUSION: HTLV-I tax sequences appear not to be present in this population of 100 blood donors negative for anti-HTLV-I.     

Randomized trial assessing the feasibility and safety of biologic parents as RBC donors for their preterm infants

BACKGROUND: Most very low birth weight (<1.0 kg) infants receive RBC transfusions. Several reports have demonstrated that RBCs stored up to 42 days can be transfused safely in small volumes to preterm infants to decrease donor exposure without consequent hyperkalemia, acidosis, or other adverse effects. Although biologic parents are likely candidates as donors of blood for their neonates, it has been suggested that their blood may be serologically incompatible with that of their infants. STUDY DESIGN AND METHODS: A two-arm randomized study was conducted to compare the feasibility and immediate safety of two single-donor programs for providing small-volume RBC transfusions to preterm infants: in one arm, infants received RBCs collected from unrelated donors and stored up to 42 days, and in the other arm, RBCs were collected from one of the biologic parents and stored identically. All infants received compatible RBCs that were WBC reduced before storage, stored in AS-3, and gamma-radiated. All transfusions were given uniformly as 15 mL per kg of RBCs transfused over 5 hours, during which time the infants were closely observed for clinical reactions. In addition, laboratory studies were performed shortly before and after each transfusion. RESULTS: A total of 40 preterm infants received 120 RBC transfusions. Biologic parents experienced several donor eligibility problems. However, once enrolled as donors, they were able to supply all RBCs needed by their infants. Significant differences in rates of clinical transfusion reactions and laboratory abnormalities were rare and had no apparent clinical importance, regardless of whether RBCs were donated by biologic parents or unrelated donors. CONCLUSION: A single-donor system, in which AS-3 RBCs were collected either from unrelated blood donors or from biologic parents and then stored up to 42 days, was able to supply small-volume RBC transfusions needed by individual preterm infants without immediate, adverse effects. Because the risk of infectious disease transmission is likely reduced by limiting donor exposure, it is logical to conclude that single-donor programs should increase transfusion safety and that biologic parents should be considered as blood donors for their infants.     

Risk factors for Trypanosoma cruzi infection in California blood donors

BACKGROUND: Trypanosoma cruzi, the protozoan parasite that causes Chagas'disease, is endemic in Central and South America and in Mexico. Risk of infection is related to exposure to insects harboring T. cruzi or to the transfusion of blood from an infected donor. Large numbers of immigrants from endemic areas reside in California, but the frequency with which persons at risk for T. cruzi contribute to the blood supply there is not known. STUDY DESIGN AND METHODS: A questionnaire was used to survey donors in 18 California donor centers for risk factors for T. cruzi infection. RESULTS: Otherwise eligible allogeneic blood donors (n = 17,521) completed questionnaires. Of this group, 427 (2.4%) had lived in endemic areas for more than 1 year, and 39 of these donors had lived in dwellings with mud walls or thatched roofs. Sixteen donors had received transfusions in endemic areas. Six donors gave a history of Chagas' disease. Fifty-seven donors (0.33% of total) had at least one risk factor for T. cruzi infection. Donors at risk for T. cruzi were found in all 18 centers studied, at a median prevalence of 1 per 340 donors. CONCLUSION: Donors at risk for T. cruzi are contributing to the blood supply throughout California. Further consideration should be given to donor screening for this transfusion-transmissible infection.     

BLOOD DONORS AND BLOOD COLLECTION: Testing blood donors for Chagas disease in the Paris area,France: first results after 18 months of screening

BACKGROUND: Chagas disease is endemic in Latin America (LA). Currently 10 million people are infected despite World Health Organization efforts aimed at preventing domestic transmission. However, with the migration of infected asymptomatic individuals to nonendemic countries, transmission of Chagas disease by transfusion may become a worldwide problem. The observation that the number of cases of Chagas disease has increased over the past 10 years in French Guiana, together with the results of a previous hospital‐based study in the Paris area, confirms the transmission of Chagas disease from patients coming from LA. For these reasons, the French authorities stopped the collection of blood in French Guiana in 2005 and began screening blood donors in the French Caribbean islands and, in 2007, in continental France. STUDY DESIGN AND METHODS: Data on birth place, mother's birth place, and travel in LA were recorded for at‐risk donors. These subjects were tested using two enzyme‐linked immunosorbent assays (ELISAs). RESULTS: Of the 312,458 individuals who gave blood in the Paris area during an 18‐month period, 30,837 were tested. Of these, 972 were born in LA, three of whom were positive for the two ELISAs and immunofluorescence tests. The prevalence of Trypanosoma cruzi–positive donors was 9.7 in 100,000 tested donors, but 0.31% among donors born in LA. Serology tests gave discrepant results in 1.02% of the samples. CONCLUSION: The efficiency of blood donor screening programs could be improved by screening only blood donors who were born in LA or who have traveled in LA for extended periods, using a single enzyme immunoassay.     

Predonation screening of blood donors with rapid tests: implementation and efficacy of a novel approach to blood safety in resource-poor settings

BACKGROUND: In sub-Saharan Africa, the percentage of screened blood is limited to approximately 75 percent for human immunodeficiency virus antibodies (anti-HIV), 50 percent for hepatitis B surface antigen, and 19 percent for hepatitis C virus antibodies (anti-HCV), mainly because of costs. STUDY DESIGN AND METHODS: In 2002 to 2003, candidate blood donors were screened before donation for HIV, HCV, and hepatitis B virus (HBV) serologic markers with rapid tests. The efficacy of this screening was assessed by nucleic acid testing (NAT) applied to pools of 10 plasma samples from donated units with a virus specific triplex assay. NAT-reactive pools were resolved by viral genome identification in individual plasma sample. Deferred candidate donors were referred to a donor-care program. RESULTS: A total of 9372 people were screened and 1534 (16.4%) were deferred. No HIV or HCV RNA-containing samples remained undetected by rapid tests unless a human testing error was involved. In contrast, 1.3 and 3.0 percent of HBV DNA-containing blood units were negative with rapid tests but were detected in individual donations with enzyme immunoassay and genomic amplification, respectively. Only half of these units were detectable in pools of 10 samples. One-third of deferred candidate donors attended the donor-care program and were informed and counseled. CONCLUSIONS: Predonation viral screening of blood donors is effective in high endemic areas, and the savings it generates may improve the safety and limit the cost of blood. Communication with deferred donors may contribute to public health. A new screening strategy associating serologic rapid test before donation and NAT on pools of 10 plasma samples after donation is proposed.     

Serologic distinction between human T-lymphotropic virus (HTLV) type I and HTLV type II

In November 1988, the Food and Drug Administration approved reagents for serologic screening for human T-lymphotropic virus type I (HTLV-I) infection in blood donors and patients suspected of having HTLV-I-related illnesses. These reagents are able to detect HTLV type II (HTLV-II), a close relative of HTLV-I with no known pathologic effect. The distinction between the two forms of HTLV is important to the donor and to any recipient of blood containing HTLV. The application to sera from 38 seropositive blood donors and 2 recipients (37 "confirmed" positive and 3 indeterminate by Western blot) of two methods (Western blot and peptide enzyme immunoassay) for serologic distinction between HTLV-I and -II is described. These results were compared to those from polymerase chain reaction (PCR) analysis of HTLV proviral DNA obtained from donor peripheral blood mononuclear cells. The peptide enzyme immunoassay was found to be less sensitive than the Western blot, but completely concordant with PCR results when differential reactivity could be established. The Western blot pattern showed complete diagnostic concordance with the samples with confirmed-positive serologic tests, but was incorrect in two HTLV-II-infected donors with indeterminate serologic tests. Thirty-three (89%) of the 37 individuals from this predominantly Native American and Hispanic group of blood donors were found to have HTLV-II. These findings confirm and extend previous reports that HTLV-I infection may be less common, and HTLV-II infection more common, than previously believed. The peptide enzyme immunoassay can provide most individuals who have positive results with the HTLV-I/II screening test with serologic distinction between HTLV-I and HTLV-II.     

北京地区部分献血员嗜人T细胞病毒I型血清抗体调查

目的 进一步了解北京地区献血员HTLV-I感染状况。方法 应用明胶颗粒凝集试验(GPAT)检测本院的749份北京地区献血员血清HTLV-I抗体。结果 均为阴性。结论 研究结果可能与近年来北京地区对献血员的严格筛选有关,其它病毒检测项目的增加可能也会减少血清HTLV-I的阳性率。     

Evidence for the chronic in vivo production of human T cell leukemia virus type I Rof and Tof proteins from cytotoxic T lymphocytes directed against viral peptides

Human T cell leukemia virus type I (HTLV-I) is a persistent virus that causes adult T cell leukemia and tropical spastic paraparesis/HTLV-I-associated myelopathy. Studies on rabbits have shown that viral proteins encoded by the open reading frames pX-I and pX-II are required for the establishment of the persistent infection. To examine the in vivo production of these proteins in humans, we have investigated whether cytotoxic T lymphocytes isolated from HTLV-I-infected individuals recognized pX-I and pX-II peptides. CD8(+) T lymphocytes to pX-I and pX-II peptides were detected in HTLV-I-infected individuals, whatever their clinical status, and even in the absence of any antigenic restimulation. These findings indicate that the HTLV-I pX-I and pX-II proteins are chronically synthesized in vivo, and are targets of the natural immune response to the virus.     

Low incidence of HTLV infections in random blood donors with indeterminate western blot patterns

Peripheral blood mononuclear cells (PBMCs) were recovered from platelet units of 61 blood donors who were HTLV-I positive and 3 blood donors who were HTLV-I negative on enzyme-linked immunosorbent assay (ELISA). Western blot analyses were performed on the sera and DNA was prepared from the PBMCs and analyzed by the polymerase chain reaction (PCR). Of the 61 repeatably reactive samples, 2 were positive, 26 were negative, and 33 were interpreted as indeterminate on Western blot. HTLV-II sequences were detected by PCR in one of the Western blot-positive samples, as well as in one Western blot-indeterminate sample that showed reactivity to p24 only. HTLV-I sequences were detected in the second Western blot-positive sample. HTLV sequences were not detected in the remaining samples, which suggested that the majority of individuals with indeterminate results on Western blots that used one set of commercially available reagents are not infected with HTLV. It is demonstrated in this study that PCR can be used not only to resolve the infection status of individuals with indeterminate Western blots but also to distinguish between HTLV-I and HTLV-II.