Human T lymphotropic virus types I and II proviral sequences in Argentinian blood donors with indeterminate Western blot patterns

Brazilian Protocol for Sexually Transmitted Infections 2020: human T-cell lymphotropic virus (HTLV) infection

This article addresses the Human T-lymphotropic virus (HTLV). This subject comprises the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health. HTLV-1/2 infection is a public health problem globally, and Brazil has the largest number of individuals living with the virus. HTLV-1 causes several clinical manifestations of neoplasm (adult T-cell leukemia/lymphoma) and inflammatory nature, such as HTLV-1-associated myelopathy and other manifestations such as uveitis, arthritis, and infective dermatitis. These pathologies have high morbidity and mortality and negatively impact the quality of life of infected individuals. This review includes relevant information for health authorities professionals regarding viral transmission, diagnosis, treatment, and monitoring of individuals living with HTLV-1 and 2 in Brazil.

HTLV-1/2 transmission can occur through blood transfusion and derivatives, injectable drug use, organ transplantation, unprotected sexual intercourse, and vertical transmission.

[Brazilian Protocol for Sexually Transmitted Infections 2020: human T cell lymphotropic virus (HTLV) infection]

This manuscript is related to the chapter about human T-cell lymphotropic virus (HTLV) that is part of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Health Ministry. HTLV-1/2 infection is a worldwide public health problem and Brazil has the largest number of individuals living with the virus. HTLV-1 causes a variety of clinical manifestations of a neoplastic nature, such as adult leukemia/T-cell lymphoma, and also of an inflammatory nature, such as HTLV-1-associated myelopathy, as well as other manifestations such as uveitis, arthritis and infective dermatitis. These pathologies have high morbidity and mortality and negatively impact the quality of life of infected individuals. This review includes relevant information for health service managers and workers regarding virus transmission modes, diagnosis, treatment and monitoring of individuals living with HTLV-1 and 2 in Brazil.

Lymphotropic Viruses EBV, KSHV and HTLV in Latin America: Epidemiology and Associated Malignancies. A Literature-Based Study by the RIAL-CYTED

The Epstein-Barr virus (EBV), Kaposi sarcoma herpesvirus (KSHV) and human T-lymphotropic virus (HTLV-1) are lymphomagenic viruses with region-specific induced morbidity. The RIAL-CYTED aims to increase the knowledge of lymphoma in Latin America (LA), and, as such, we systematically analyzed the literature to better understand our risk for virus-induced lymphoma. We observed that high endemicity regions for certain lymphomas, e.g., Mexico and Peru, have a high incidence of EBV-positive lymphomas of T/NK cell origin. Peru also carries the highest frequency of EBV-positive classical Hodgkin lymphoma (HL) and EBV-positive diffuse large B cell lymphoma, not otherwise specified (NOS), than any other LA country. Adult T cell lymphoma is endemic to the North of Brazil and Chile. While only few cases of KSHV-positive lymphomas were found, in spite of the close correlation of Kaposi sarcoma and the prevalence of pathogenic types of KSHV. Both EBV-associated HL and Burkitt lymphoma mainly affect young children, unlike in developed countries, in which adolescents and young adults are the most affected, correlating with an early EBV seroconversion for LA population despite of lack of infectious mononucleosis symptoms. High endemicity of KSHV and HTLV infection was observed among Amerindian populations, with differences between Amazonian and Andean populations.

Line Immunoassay for Confirmation and Discrimination of Human T-Cell Lymphotropic Virus Infections in Inconclusive Western Blot Serum Samples from Brazil

Difficulties in confirming and discriminating human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by serological Western blot (WB) assays (HTLV Blot 2.4; MP Biomedicals) have been reported in Brazil, mainly in HIV/AIDS patients, with a large number of WB-indeterminate and WB-positive but HTLV-untypeable results. Nonetheless, a line immunoassay (LIA) (INNO-LIA HTLV-I/II; Fujirebio) provided enhanced specificity and sensitivity for confirming HTLV-1/2 infections.

Difficulties in confirming and discriminating human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by serological Western blot (WB) assays (HTLV Blot 2.4; MP Biomedicals) have been reported in Brazil, mainly in HIV/AIDS patients, with a large number of WB-indeterminate and WB-positive but HTLV-untypeable results. Nonetheless, a line immunoassay (LIA) (INNO-LIA HTLV-I/II; Fujirebio) provided enhanced specificity and sensitivity for confirming HTLV-1/2 infections. To add information concerning the improved ability of the LIA in relation to WB when applied to samples of individuals from different risk groups from Brazil, we performed the present study. Three groups were analyzed: group 1 (G1), with 62 samples from HIV/AIDS patients from São Paulo, SP (48 WB indeterminate and 14 HTLV untypeable); group 2 (G2), with 24 samples from patients with hepatitis B or hepatitis C from São Paulo (21 WB indeterminate and 3 HTLV untypeable; 17 HIV seropositive); and group 3 (G3), with 25 samples from an HTLV outpatient clinic in Salvador, Bahia (16 WB indeterminate and 9 HTLV untypeable; all HIV seronegative). Overall, the LIA confirmed HTLV-1/2 infection (HTLV-1, HTLV-2, or HTLV) in 66.1% (G1), 83.3% (G2), and 76.0% (G3) of samples. Interestingly, the majority of WB-indeterminate results were confirmed by the LIA as being HTLV-2 positive in G1 and G2 but not in G3, in which the samples were defined as being HTLV-1 or HTLV positive. These results agree with the virus types that circulate in such patients of different regions in Brazil and emphasize that the LIA is the best serological test for confirming HTLV-1 and HTLV-2 infections, independently of being applied in HTLV-monoinfected or HTLV-coinfected individuals.

Proviral Features of Human T Cell Leukemia Virus Type 1 in Carriers with Indeterminate Western Blot Analysis Results

Western blotting (WB) for human T cell leukemia virus type 1 (HTLV-1) is performed to confirm anti-HTLV-1 antibodies detected at the initial screening of blood donors and in pregnant women. However, the frequent occurrence of indeterminate results is a problem with this test. We therefore assessed the cause of indeterminate WB results by analyzing HTLV-1 provirus genomic sequences. A quantitative PCR assay measuring HTLV-1 provirus in WB-indeterminate samples revealed that the median proviral load was approximately 100-fold lower than that of WB-positive samples (0.01 versus 0.71 copy/100 cells). Phylogenic analysis of the complete HTLV-1 genomes of WB-indeterminate samples did not identify any specific phylogenetic groups. When we analyzed the nucleotide changes in 19 HTLV-1 isolates from WB-indeterminate samples, we identified 135 single nucleotide substitutions, composed of four types, G to A (29%), C to T (19%), T to C (19%), and A to G (16%). In the most frequent G-to-A substitution, 64% occurred at GG dinucleotides, indicating that APOBEC3G is responsible for mutagenesis in WB-indeterminate samples. Moreover, interestingly, five WB-indeterminate isolates had nonsense mutations in Pol and/or Tax, Env, p12, and p30. These findings suggest that WB-indeterminate carriers have low production of viral antigens because of a combination of a low proviral load and mutations in the provirus, which may interfere with host recognition of HTLV-1 antigens.

Comparative performances of serologic and molecular assays for detecting human T lymphotropic virus type 1 and type 2 (HTLV-1 and HTLV-2) in patients infected with human immunodeficiency virus type 1 (HIV-1)

The present study evaluated several techniques currently available (commercial kits and in-house assays) for diagnosing human T lymphotropic viruses types 1 and 2 in two groups of patients enrolled at HIV/AIDS specialized care services in São Paulo: Group 1 (G1), n = 1608, 1237 male/371 female, median age 44.3 years old, majority using highly active antiretroviral therapy (HAART); G2, n = 1383, 930 male/453 female, median age of 35.6 years old, majority HAART naïve. Enzyme immunoassays [(EIA) Murex and Gold ELISA] were employed for human T lymphotropic viruses types 1 and 2 screening; Western blotting (WB), INNO-LIA (LIA), real-time PCR pol (qPCR), and nested-PCR-RFLP (tax) were used to confirm infection. Samples were considered human T lymphotropic viruses types 1 and 2 positive when there was reactivity using at least one of the four confirmatory assays. By serological screening, 127/2991 samples were positive or borderline, and human T lymphotropic virus infection was confirmed in 108 samples (three EIA-borderline): 56 human T lymphotropic virus type 1 [G1 (27) + G2 (29)]; 45 human T lymphotropic virus type 2 [G1 (21) + G2 (24)]; one human T lymphotropic virus type 1 + human T lymphotropic virus type 2 (G2); six human T lymphotropic virus [G1 (2) + G2 (4)]. Although there were differences in group characteristics, human T lymphotropic viruses types 1 and 2 prevalence was similar [3.1% (G1) and 4.2% (G2), p = 0.113]. The overall sensitivities of LIA, WB, qPCR, and PCR-RFLP were 97.2%, 82.4%, 68.9%, and 68.4%, respectively, with some differences among groups, likely due to the stage of human T lymphotropic virus infection and/or HAART duration. Indeterminate immunoblotting results were detected in G2, possibly due to the seroconversion period. Negative results in molecular assays could be explained by the use of HAART, the occurrence of defective provirus and/or the low circulating proviral load. In conclusion, when determining the human T lymphotropic virus infection, the findings highlight that there is a need to consider the blood samples with borderline results in screening assays. Of all the tested assays, LIA was the assay of choice for detecting human T lymphotropic virus type 1 and human T lymphotropic virus type 2 in human immunodeficiency virus type 1-infected patients.

Serological and Molecular Methods to Study Epidemiological Aspects of Human T-Cell Lymphotropic Virus Type 1 Infection

We estimated that at least 5-10 million individuals are infected with HTLV-1. Importantly, this number is based on the study of nearly 1.5 billion people living in known human T-cell lymphotropic virus type 1 (HTLV-1) endemic areas, for which reliable epidemiological data are available. However, for some highly populated regions including India, the Maghreb, East Africa, and some regions of China, no consistent data are yet available which prevents a more accurate estimation. Thus, the number of HTLV-1 infected people in the world is probably much higher. The prevalence of HTLV-1 prevalence varies depending on age, sex, and economic level in most HTLV-1 endemic areas. HTLV-1 seroprevalence gradually increases with age, especially in women. HTLV-1 has a simian origin and was originally acquired by humans through interspecies transmission from STLV-1 infected monkeys in the Old World. Three main modes of HTLV-1 transmission have been described; (1) from mother-to-child after prolonged breast-feeding lasting more than six months, (2) through sexual intercourse, which mainly, but not exclusively, occurs from male to female and lastly, (3) from contaminated blood products, which contain HTLV-1 infected lymphocytes. In specific areas, such as Central Africa, zoonotic transmission from STLV-1 infected monkeys to humans is still ongoing.The diagnostic methods used to study the epidemiological aspects of HTLV-1 infection mainly consist of serological assays for the detection of antibodies specifically directed against different HTLV-1 antigens. Screening tests are usually based on enzyme-linked immunoabsorbent assay (ELISA), chemiluminescence enzyme-linked immunoassay (CLEIA) or particle agglutination (PA). Confirmatory tests include mostly Western blots (WB)s or innogenetics line immunoassay (INNO-LIA™) and to a lesser extent immunofluorescence assay (IFA). The search for integrated provirus in the DNA from peripheral blood cells can be performed by qualitative and/or quantitative polymerase chain reaction (qPCR). qPCR is widely used in most diagnostic laboratories and quantification of proviral DNA is useful for the diagnosis and follow-up of HTLV-1 associated diseases such as adult T-cell leukemia (ATL) and tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM). PCR also provides amplicons for further sequence analysis to determine the HTLV-1 genotype present in the infected person. The use of new generation sequencing methodologies to molecularly characterize full and/or partial HTLV-1 genomic regions is increasing. HTLV-1 genotyping generates valuable molecular epidemiological data to better understand the evolutionary history of this virus.

Low Proviral Load is Associated with Indeterminate Western Blot Patterns in Human T-Cell Lymphotropic Virus Type 1 Infected Individuals: Could Punctual Mutations be Related?

BACKGROUND

indeterminate Western blot (WB) patterns are a major concern for diagnosis of human T-cell lymphotropic virus type 1 (HTLV-1) infection, even in non-endemic areas.

OBJECTIVES

(a) to define the prevalence of indeterminate WB among different populations from Argentina; (b) to evaluate if low proviral load (PVL) is associated with indeterminate WB profiles; and (c) to describe mutations in LTR and tax sequence of these cases.

RESULTS

Among 2031 samples, 294 were reactive by screening. Of them, 48 (16.3%) were WB indeterminate and of those 15 (31.3%) were PCR+. Quantitative real-time PCR (qPCR) was performed to 52 HTLV-1+ samples, classified as Group 1 (G1): 25 WB+ samples from individuals with pathologies; Group 2 (G2): 18 WB+ samples from asymptomatic carriers (AC); and Group 3 (G3): 9 seroindeterminate samples from AC. Median PVL was 4.78, 2.38, and 0.15 HTLV-1 copies/100 PBMCs, respectively; a significant difference (p=0.003) was observed. Age and sex were associated with PVL in G1 and G2, respectively. Mutations in the distal and central regions of Tax Responsive Elements (TRE) 1 and 2 of G3 were observed, though not associated with PVL.The 8403A>G mutation of the distal region, previously related to high PVL, was absent in G3 but present in 50% of WB+ samples (p = 0.03).

CONCLUSIONS

indeterminate WB results confirmed later as HTLV-1 positive may be associated with low PVL levels. Mutations in LTR and tax are described; their functional relevance remains to be determined.

[Serological diagnosis of HTLV-1/2: combination of screening assays to define the serological status in blood donors]

Alternative algorithms were evaluated in order to reduce the number of false reactive results for antibodies against HTLV-1/2. From 20,210 samples tested, 0.37% (74/20,210) was reactive by ELISA Murex. Of these, 23 were confirmed as positive by the indirect immunofluorescence assay whereas 51 were negative, being the positive predictive value (PPV) 31.08%. From a combination of the ELISA Murex assay with the particle agglutination assay (PA) and ELISA MP, the following results were obtained: 26/74 were reactive by ELISA Murex and PA, PPV 88.5% and 32/74 were reactive by ELISA Murex and ELISA MP, PPV 71.8 %. The ROC curve analysis determined that for an RP 4.74, the values for sensitivity, specificity, PPV and NPV by ELISA Murex were 100%, 98.04%, 95.8% and 100%, respectively. We propose that reactive samples by ELISA Murex with an RP d 4.74 should be retested in duplicate by PA, and the resulting concordantly nonreactive samples should be defined as negative for HTLV-1/2.

A new and frequent human T-cell leukemia virus indeterminate Western blot pattern: epidemiological determinants and PCR results in central African inhabitants

Human T-cell leukemia virus (HTLV) indeterminate Western blot (WB) serological patterns are frequently observed in plasma/serum from persons living in intertropical areas. In the framework of ongoing projects on HTLV-1/2 and related viruses in Central Africa, we systematically analyzed plasma from villagers living in South Cameroon by WB. The group included 1,968 individuals (mean age, 44 years; age range, 5 to 90 years; 978 women/990 men), both Bantus (1,165) and Pygmies (803). Plasma samples were tested by WB analysis (MPD HTLV Blot 2.4) and interpreted according to the manufacturer's instructions. Only clear bands were considered in the analysis. Among the 1,968 plasma samples, 38 (1.93%) were HTLV-1, 13 (0.66%) were HTLV-2, and 6 (0.3%) were HTLV WB seropositive. Furthermore, 1,292 (65.65%) samples were WB sero-indeterminate, including 104 (5.28%) with an HTLV-1 Gag-indeterminate pattern (HGIP) and 68 (3.45%) with a peculiar yet unreported pattern exhibiting mostly a strong shifted GD21 and a p28. The other 619 (31.45%) samples were either WB negative or exhibited other patterns, mostly with unique p19 or p24 bands. DNA, extracted from peripheral blood buffy coat, was subjected to PCR using several primer pairs known to detect HTLV-1/2/3/4. Most DNAs from HTLV-1- and HTLV-seropositive individuals were PCR positive. In contrast, all the others, from persons with HTLV-2, HGIP, new WB, and other indeterminate patterns, were PCR negative. Epidemiological determinant analysis of the persons with this new peculiar WB pattern revealed that seroprevalence was independent from age, sex, or ethnicity, thus resembling the indeterminate profile HGIP rather than HTLV-1. Moreover, this new pattern persists over time.

Decline in prevalence and asymmetric distribution of human T cell lymphotropic virus 1 and 2 in blood donors, State of Minas Gerais, Brazil, 1993 to 2007

INTRODUCTION

Human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) are endemic in Brazil and are screened for in transfusion services since 1993. This study evaluated the evolution of the prevalence of HTLV-1 and 2 in blood donors of the Hemominas Foundation from 1993 to 2007, and its geographical distribution in State of Minas Gerais, Brazil.

METHODS

The Hemominas Foundation is a centralized blood center in Minas Gerais, Brazil. The sources of data were the Hemominas Foundation Technical Bulletin and files from the centralized serological laboratory. Donors were tested in the period using enzyme linked immuno sorbent assays (ELISA), followed by Western blot, when repeatedly reactive. The data were analyzed by EPIINFO 6.2 and TABWIN 3.5 softwares.

RESULTS

The average seroprevalence in the period 1993-2007 was 0.1%. A steady decline occurred from 0.4% in 1993 to below 0.1% in 2002 and later, with a transient peak of 0.5% in 1994. HTLV reactivity distribution was asymmetrical in the state, with regions of higher prevalence, interspersed with low prevalence areas. Comparison of positive and negative donors verified that increasing age was proportional to virus positivity. Odds ratio for age ranged from 1.43 (30 to 39 years-old) to 3.09 (50 to 65 years-old). Women had a greater chance of being positive (OR-1.64), as previously described.

CONCLUSIONS

Possible explanations for HTLV-1/2 prevalence decline are the exclusion of positive donors from the donor pool, an increase in repeat donors and ELISA test improvement, with reduction in the number of false positive results.

The prevalence and significance of HTLV-I/II seroindeterminate Western blot patterns

Human T-lymphotropic virus type I (HTLV-I) infects an estimated 15–20 million persons worldwide. A number of diseases have been associated with the virus including adult T-cell leukemia (ATL), HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV-I uveitis, and HTLV-I-associated infective dermatitis. Once it was shown that there is an increased risk for developing HAM/TSP associated with blood transfusion, screening for HTLV-1 among blood banks was implemented in Japan, United States, France, and the Netherlands. This process includes detection by an enzyme immunoassay (EIA) followed by a confirmatory Western blot (WB) in which recombinant proteins specific for HTLV-I Env glycoproteins are incorporated into WB strips. HTLV-I seropositive results are defined by the presence of antibodies against either gp46 or gp62/68 (both Env protein bands) and either p19, p24, or p53 (one of the gag bands). HTLV-II seropositivity is confirmed by the presence of rgp46-II. However, numerous cases have been documented in which serum samples are reactive by EIA, but an incomplete banding pattern is displayed by subsequent confirmatory WB. Although the significance of these HTLV-I/II seroindeterminates is unclear, it may suggest a much higher incidence of exposure to HTLV-I/II than previously estimated.

Molecular analysis of human T cell lymphotropic virus type 1 and 2 (HTLV-1/2) seroindeterminate blood donors from Northeast Iran: evidence of proviral tax, env, and gag sequences

Human T cell lymphotropic virus type 1 and 2 (HTLV-1/2) Western blot indeterminate results are a problem for blood banks in endemic areas. To determine the prevalence of HTLV-1/2 infection among indeterminate donors, we analyzed 130 cases from Mashhad, an HTLV-1/2 endemic area in Northeast Iran. The most frequent Western blot bands were GD21 alone (37.2%) followed by rgp46-2 alone (32.1%). We further tested 40 available DNA samples of these cases by PCR for viral sequences, tax, gag, and pol, and found five cases (12.5%) to be positive for two or three HTLV-1 genes. There were no significant age, sex, and blood group differences between PCR-positive and PCR-negative cases. Among PCR-positive individuals, the most prevalent Western blot bands were variable combinations of rgp46-1, GD21, and gp21. The mean of the optical density (OD) of the enzyme-linked immunosorbent assay (ELISA) test was significantly higher in PCR-positive individuals. The frequency of the rgp46-1 band was also significantly higher in PCR-positive cases compared to PCR-negative ones. In conclusion, the majority of HTLV-indeterminate donors lack the HTLV provirus and therefore are not considered infected. However, in some cases with higher ODs in the ELISA test and seroreactivity to env proteins, rgp46-1 and GD21 in particular may be indicative of infection and need further evaluation by molecular methods.

Human T-Lymphotropic Virus (HTLV) Type I in vivo Integration in Oral Keratinocytes

Although the infection of HTLV-1 to cell components of the mouth have been previously reported, there was not until this report, a detailed study to show the characteristics of such infection. From 14 Tropical Spastic Paraparesis/HTLV-1-Associated Myelopathy (HAM/TSP) patients and 11 asymptomatic carrier individuals (AC) coming from HTLV-1 endemic areas of southwest Pacific of Colombia, infected oral mucosa cells were primary cultured during five days. These cell cultures were immunophenotyped by dual color fluorescence cell assortment using different lymphocyte CD markers and also were immunohistochemically processed using a polyclonal anti-keratin antibody. Five days old primary cultures were characterized as oral keratinocytes, whose phenotype was CD3- /CD4-/CD8-/CD19-/CD14-/CD45-/A575-keratin+. From DNA extracted of primary cultures LTR, pol, env and tax HTLV-1 proviral DNA regions were differentially amplified by PCR showing proviral integration. Using poly A+ RNA obtained of these primary cultures, we amplify by RT-PCR cDNA of tax and pol in 57.14% (8/14) HAM/TSP patients and 27.28% (3/11) AC. Tax and pol poly A+ RNA were expressed only in those sIgA positive subjects. Our results showed that proviral integration and viral gene expression in oral keratinocytes are associated with a HTLV-1 specific local mucosal immune response only in those HTLV-1 infected individuals with detectable levels of sIgA in their oral fluids. Altogether the results gave strong evidence that oral mucosa infection would be parte of the systemic spreading of HTLV-1 infection.

Quantitation of HTLV-I proviral load by a real-time PCR assay using SYBR Green: comparison of two methods for DNA isolation

A real-time quantitative PCR (qPCR) assay using SYBR Green was developed to determine HTLV-I proviral load (pVL) in peripheral blood mononuclear cells (PBMCs), and its performance was evaluated with samples processed as cell lysates and DNA isolated by salting out. Primers targeting the pol region were standardized against the MT2 cell line and HTLV-I copy number was normalized to the amount of cellular DNA by quantitation of the albumin gene. The sensitivity, specificity and reproducibility of the qPCR were assessed in the two methods used for DNA processing. The assay had a limit of detection of 400 HTLV-I copies/10(6) PBMCs for both methods, with a broad range of quantitation (2.6log(10) to >5log(10)), and without cross-reactivity with HTLV-II or with HIV-1. The inter- and intra-assay coefficients of variation were less than 2.4%. HTLV-I pVL quantitation in seven blood donor samples processed as either cell lysates or isolated DNA by salting out showed a strong linear correlation and no difference in the calculated pVL (Fisher's exact test, p>0.05). The assay was found to be a low cost, robust and reproducible assay for quantifying HTLV-I pVL in samples processed as cell lysates or as isolated DNA.

HTLV infection and its implication in gynaecology and obstetrics

INTRODUCTION

Worldwide, 20-30 million people are estimated to be infected with HTLV. HTLV-1 is endemic in Western Africa and Southern Japan, whereas HTLV-2 is considered to be spread among native American people.

MATERIALS AND METHODS

The impact of HTLV in gynaecology and obstetrics is being reviewed. Search strategy and selection criteria for identifying relevant data were performed by searching Medline, Current Contents, Web of Science, Embase and references from relevant articles. English and German gynaecological and infectious diseases textbooks as well as national and international guidelines and recommendations were also reviewed.

RESULTS

Transmission may occur by sexual intercourse or cellular blood products. Although materno-fetal transmission is debated, transmission through maternal breast milk has been confirmed. An HTLV-infection can lead to adult T-cell leukaemia (ATL) or cumulative opportunistic and neurological disorders that can occur with varying degrees of severity. Diagnosis can be done by antibody detection via the use of ELISA and western blot analysis as well as PCR diagnosis.

CONCLUSION

Due to inadequate treatment options and the lack of an effective vaccination, prevention is currently only possible by restricting transmission, including the usage of condoms during sexual intercourse or avoiding breastfeeding in HTLV-seropositive mothers. If, due to socio-economic reasons, breastfeeding cannot be avoided, short-term breastfeeding for a maximum of up to 6 months is suggested.

Age and gender specific prevalence of HTLV-1

BACKGROUND

The seroprevalence of Human T-cell Leukemia Virus Type 1 (HTLV-1) is female predominant despite the higher incidence of Adult T-cell Leukemia (ATL) in males. If the mother-to-child transmission of HTLV-1 is more common for male infants than in female infants, longer exposure to the virus for males may explain the paradoxically higher incidence of ATL.

OBJECTIVES

To test the hypothesis that the seroprevalence of HTLV-1 is male predominant during adolescence.

STUDY DESIGN

The presence of HTLV-1 antibody in 272,043 blood samples donated to a regional blood bank in an HTLV-1 high-endemic region was assessed.

RESULTS

The entire population of female donors had a significantly higher seroprevalence compared to males (2.05% and 1.80%, respectively, p<0.0001). However, compared with male donors, the carrier rate for female donors was lower for the youngest subgroup (16-19 years, p=0.0011); was similar for the next two age subgroups (20-29 years and 30-39 years); and was significantly higher for the last two age subgroups (40-49 years and over 50-64 years, both p<0.0001). In general, older age subgroups led to higher seroprevalence in both genders.

CONCLUSIONS

HTLV-1 infection is more common for males until after age 20, when male to female sexual transmission becomes likely. This suggests that mother-to-child transmission is more common for males.

Molecular evidence of human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2) infections in HTLV seroindeterminate individuals from São Paulo, Brazil

BACKGROUND

Using enzyme immunoassays and Western blot (Wb) tests, HTLV serodiagnosis yields indeterminate results in a significant number of cases.

OBJECTIVE

To determine the prevalence of HTLV infection among HTLV-seroindeterminate individuals.

STUDY DESIGN

We studied peripheral blood mononuclear cells from 65 anti-HTLV Wb-seroindeterminate individuals by attempting to amplify proviral DNA sequences (tax and pol) to identify HTLV-1 and HTLV-2 infections.

RESULTS

These 65 specimens exhibited predominantly (43%) anti-HTLV antibodies to gag-coded antigens in the absence of anti-p24 on Wb analysis. Tax proviral sequences were detected in 6 (9.2%) samples. According to restricted fragment polymorphism analysis (RFLP), we identified HTLV-1 proviral DNA in 4 samples, HTLV-2 in one and sequences from both in another. Nested PCR for the pol region was positive in 3 (4.6%) specimens, which were also positive for tax sequences. After hybridization HTLV-1 infection was confirmed in 2 samples (3.1%) and HTLV-2 in another (1.5%). Detection of a single HTLV DNA sequence may be due to infection by defective provirus, but its significance remains undefined. In this cohort, no Wb reactivity pattern was predictive of proviral detection. HTLV-1 infection was demonstrated in an individual who had Wb reactivity to gag-coded antigens only.

CONCLUSIONS

This emphasizes the importance of clinical and laboratory follow-up of HTLV-seroindeterminate individuals from endemic areas.

Human T-lymphotropic virus 1: recent knowledge about an ancient infection

Human T-lymphotropic virus 1 (HTLV-1) has infected human beings for thousands of years, but knowledge about the infection and its pathogenesis is only recently emerging. The virus can be transmitted from mother to child, through sexual contact, and through contaminated blood products. There are areas in Japan, sub-Saharan Africa, the Caribbean, and South America where more than 1% of the general population is infected. Although the majority of HTLV-1 carriers remain asymptomatic, the virus is associated with severe diseases that can be subdivided into three categories: neoplastic diseases (adult T-cell leukaemia/lymphoma), inflammatory syndromes (HTLV-1-associated myelopathy/tropical spastic paraparesis and uveitis among others), and opportunistic infections (including Strongyloides stercoralis hyperinfection and others). The understanding of the interaction between virus and host response has improved markedly, but there are still no clear surrogate markers for prognosis and there are few treatment options.

Human T-lymphotropic virus type 1 (HTLV-1) prevalence and quantitative detection of DNA proviral load in individuals with indeterminate/positive serological results

BACKGROUND

HTLV-1 infection is currently restricted to endemic areas. To define the prevalence of HTLV-1 infection in patients living in Italy, we first carried out a retrospective serological analysis in a group of people originating from African countries referred to our hospital from January 2003 to February 2005. We subsequently applied a real time PCR on peripheral blood mononuclear cells from subjects with positive or indeterminate serological results.

METHODS

All the sera were first analysed by serological methods (ELISA and/or Western Blotting) and then the peripheral blood mononuclear cells from subjects with positive or inconclusive serological results were analyzed for the presence of proviral DNA by a sensitive SYBR Green real time PCR. In addition, twenty HTLV-I ELISA negative samples were assayed by real time PCR approach as negative controls.

RESULTS

Serological results disclosed serum reactivity by ELISA (absorbance values equal or greater than the cut-off value) in 9 out of 3408 individuals attending the Sexually Transmitted Diseases Clinic and/or Oncology Department, and 2 out 534 blood donors enrolled as a control population. Irrespective of positive or inconclusive serological results, all these subjects were analyzed for the presence of proviral DNA in peripheral blood mononuclear cells by SYBR real time PCR. A clear-cut positive result for the presence of HTLV-1 DNA was obtained in two subjects from endemic areas.

CONCLUSION

SYBR real time PCR cut short inconclusive serological results. This rapid and inexpensive assay showed an excellent linear dynamic range, specificity and reproducibility readily revealing and quantifying the presence of virus in PBMCs. Our results highlight the need to monitor the presence of HTLV-1 in countries which have seen a large influx of immigrants in recent years. Epidemiological surveillance and correct diagnosis are recommended to verify the prevalence and incidence of a new undesirable phenomenon.

Human T-cell lymphotropic virus types I and II (HTLV-I and -II) infection among seroindeterminate cases in Argentina

Human T-cell lymphotropic virus (HTLV) seroindeterminate cases have been reported among blood donors (BD) and in at-risk populations worldwide, including Argentina. The objective of the present work was to study the presence of HTLV-I/II infection and its association to specific Western blot (WB) patterns among healthy BD and at-risk populations in Argentina. We analyzed 83 HTLV-I/II seroindeterminate WB cases diagnosed among BD (n = 49) and in different at-risk populations (n = 34) for human retroviruses infections. Multiple indeterminate WB patterns were observed. Out of the total, 13.2% (11/83) of the cases were found to be HTLV-I/II positive by nested-PCR (n-PCR), including 13.2% (11/83) HTLV-I and 2.4% (2/83) presenting HTLV-I and -II co-infection. Most of their serological profiles showed reactivity to gag or env codified proteins. Two samples amplified only one of the six analyzed genes (1 HTLV-I pol gene and 1 HTLV-II tax gene). There was no association between the presence of Trypanosoma cruzi infection and an HTLV-I/II indeterminate WB pattern (only 3 of the 83 samples were positive for T. cruzi antibodies). In conclusion, the majority of HTLV-seroindeterminate WB donors lacked HTLV provirus and was thus considered uninfected. However, when seroreactivity to Env and Gag proteins are observed on the WB and especially in at-risk populations, HTLV infection should be suspected; such individuals should be followed-up and retested.