Human retroviruses (HIV and HTLV) in Brazilian Indians: seroepidemiological study and molecular epidemiology of HTLV type 2 isolates

HTLV-1/2 in Indigenous Peoples of the Brazilian Amazon: Seroprevalence, Molecular Characterization and Sociobehavioral Factors Related to Risk of Infection

HTLV-1/2 infection is endemic in Indigenous peoples of the Americas. Its origin is attributed to the migratory flow of Amerindian ancestral peoples. The present study aimed to investigate the seroprevalence of HTLV-1/2 infection in Indigenous peoples of the Brazilian Amazon. A total of 3350 Indigenous people belonging to 15 communities were investigated. The investigation was performed using serological (ELISA), molecular (qPCR) and confirmatory (Western blot and/or Inno-Lia) tests to detect and differentiate the infection. The seroprevalence was 8.3% for HTLV-1/2 infection, with 0.1% of individuals seropositive for HTLV-1 and 8.1% for HTLV-2. The prevalence of infection was statistically higher in women (10.1%) than in men (6.5%) (p = 0.0002). This female predominance was observed in all age groups; in females the prevalence was significant from 41 years old (p < 0.0001) and in males from 51 years old (p < 0.0001). Here, we present a prevalence of HTLV-1/2 among Indigenous peoples of the Brazilian Amazon. The endemic infection in these groups must reflect the different epidemiological profiles observed in these peoples, such as sexual transmission through rejection of condom use, breastfeeding, especially in cases of cross-breastfeeding, and the high rate of pregnancy in the villages.

Reflection About the Ancient Emergence of HTLV-2 Infection

During millions of years, viruses have emerged and reemerged, with imbalance of photogenicity and transmissivity overtime. This letter describes that sometimes the nomenclature is uncertain what may actually happen during retrovirus evolution nowadays. This article discusses a possibility that human T-lymphotropic virus type 2 (HTLV-2) has been processed to incorporate the human genome in the last millions of years. Persistent viruses such as human immunodeficiency virus type 1 (HIV-1), HIV-2, and human T cell lymphotropic type 2 may also have potential of endogenization instead of a cytolytic process in a long time.

HTLV infection in Brazil's second-largest indigenous reserve

Human T-lymphotropic viruses 1 and 2 (HTLV-1/2) have a worldwide distribution. HTLV-1 has been associated with several diseases, including an aggressive malignant disease known as adult T-cell leukemia/lymphoma and a chronic inflammatory neurological disease called HTLV-1-associated myelopathy, while HTLV-2 has not been definitively associated with diseases. HTLV-2 is most prevalent in specific groups such as injecting drug users and the indigenous population. In Brazil, most studies about HTLV in indigenous are carried out in indigenous communities from the north of the country. Mato Grosso do Sul (MS), Central Brazil, has the second-largest indigenous population in Brazil. However, there is no available data about HTLV infection in this group. We conducted the first investigation of HTLV-1/2 infection prevalence in the indigenous population from Jaguapiru and Bororó villages in Dourados City, MS, to provide the prevalence and molecular characterization of HTLV. For that, a total of 1875 indigenous participated in the study. All the serum samples were screened by an enzyme-linked immunosorbent assay commercial kit for the presence of anti-HTLV-1/2 antibodies. Positive samples were confirmed by HTLV-1/2 Western Blot assay. The HTLV-1 5’LTR region was detected by nested PCR amplification and sequenced by Sanger. Most of the study population declared belonging to Guarani-Kaiowá ethnicity (69.18%), 872 (46.51%), and 1003 (53.49%) were from Jaguapiru and Bororó villages, respectively. The median age of participants was 31 years, and 74.24% were females. Two individuals were detected with HTLV-1 (0.1%; CI 95% 0.1–0.2). The phylogenetic analysis revealed that isolates belong to the Cosmopolitan subtype and the Transcontinental subgroup (HTLV-1aA). The low HTLV-1 prevalence found in this study is similar to that observed among blood donors, and pregnant populations from Mato Grosso do Sul. The absence of HTLV-2 infection among these Brazilian indigenous communities would suggest a distinct behavior pattern from other indigenous populations in Brazil.

HIV-1 genetic diversity and drug resistance mutations in the northern Brazilian region

Brazil is a huge continental country with striking geographic differences which are well illustrated in the HIV/AIDS epidemic. Contrasting with the significant decline in the national AIDS detection rate in the last decade, a linear growth has been reported in the Northern region. Despite its public health and epidemiologic importance, there is scarce HIV-1 molecular data from Northern Brazil. This scoping review summarizes recent epidemiologic data with special emphasis on HIV-1 genetic diversity and antiretroviral drug resistance mutations in patients from the seven Northern states of Brazil. Studies from the Northern Brazil on different HIV-1 genomic regions, mostly pol (protease/reverse transcriptase) sequences of naïve/antiretroviral treated adults/children were retrieved from PubMed/MEDLINE electronic database. These studies indicate a consistent molecular profile largely dominated by HIV-1 subtype B with minor contribution of subtypes F1 and C and infrequent detection of other subtypes (A1, D, K), recombinants (BF1, BC), circulating recombinant forms (CRF) as the new CRF90_BF1 and CRF02_AG-like, CRF28–29_BF-like, CRF31_BC-like, and a potential new CRF_BF1. This pattern indicates a founder effect of subtype B and the introduction of non-B-subtypes and recombinants probably generated in the Southern/Southeastern regions. In naïve populations transmitted drug resistance (TDR) can impact the outcome of first-line antiretroviral treatment and prophylactic/preventive regimens. In the Northern region TDR rates are moderate while patients failing highly active antiretroviral therapy (HAART) showed high prevalence of acquired drug resistance mutations. The limited HIV-1 molecular data from Northern Brazil reflects the great challenges to generate comprehensive scientific data in isolated, underprivileged areas. It also highlights the need to invest in local capacity building which supported by adequate infrastructure and funding can promote robust research activities to help reduce the scientific asymmetries in the Northern region. Currently the impacts of the overwhelming COVID-19 pandemic on the expanding HIV/AIDS epidemic in Northern Brazil deserves to be closely monitored.

The Epidemiological Impact of STIs among General and Vulnerable Populations of the Amazon Region of Brazil: 30 years of Surveillance

Sexually transmitted infections (STIs) represent a worldwide public health problem and, although many of them are curable, they continue to be neglected, especially in areas with a low human development index, such as in the northern region of Brazil. This review describes the results of 30 years of studies at the Virus Laboratory at the Federal University of Pará, including the prevalence and molecular epidemiology of HIV-1, HTLV-1/2, HPV, HBV, Treponema pallidum and Chlamydia trachomatis among urban and non-urban populations, and also in vulnerable groups in the Brazilian Amazon. Control strategies and challenges in preventing STIs are discussed considering this immense geographic region, where essential health services are unable to reach the entire population, especially the most vulnerable, such as female sex workers, people who use illicit drugs, remnants of quilombolos and indigenous communities.

HTLV-1, ATLL, severe hypercalcaemia and HIV-1 co-infection: an overview

HIV and HTLV (Human T-ymphotropic Virus) are the only known retroviruses responsible for causing infection in humans. HTLV-1 and HIV-1 are frequent co-pathogens, however, despite its potential for accelerated progression of HIV disease and the risk of developing adult T-cell lymphoma/leukemia (ATLL), HTLV-1 is seldom considered for investigation in the HIV-1 positive individual. Severe/refractory hypercalcaemia, unresponsive to conventional calcium lowering therapy may complicate up to 70% of cases of ATLL. In addition, HTLV-1 and ATLL have both been associated with a rise in dysfunctional CD4 lymphocytes, thereby conveying a false sense of immune competence in the HIV-1 infected individual.

Human T-Cell Lymphotropic Virus Types 1 and 2 Seropositivity among Blood Donors at Mbarara Regional Blood Bank, South Western Uganda

Background. The human T-cell lymphotropic virus types 1 and 2 (HTLV 1/2) are retroviruses associated with different pathologies. HTLV-1 causes adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP); HTLV-2 is not clearly associated with a known clinical disease. Both viruses may be transmitted by whole blood transfusion, from mother to child predominantly through breastfeeding, and by sexual contact. Presently, none of the regional blood banks in Uganda perform routine pretransfusion screening for HTLV. The aim of this study was to determine the prevalence of anti-human T-cell lymphotropic virus types 1/2 (HTLV-1/2) antibodies among blood donors at Mbarara Regional Blood Bank in South Western Uganda. A cross-sectional study was conducted between June 2014 and September 2014. Methodology. Consecutive blood samples of 368 blood donors were screened for anti-HTLV-1/2 antibodies using an enzyme linked immunosorbent assay (ELISA). Samples reactive on a first HTLV-1/2 ELISA were further retested in duplicate using the same ELISA. Of the three hundred and sixty-eight blood donors (229 (62.2%) males and 139 (37.8%) females), only two male donors aged 20 and 21 years were HTLV-1/2 seropositive, representing a prevalence of 0.54%. Conclusion. HTLV-1/2 prevalence is low among blood donors at Mbarara Regional Blood Bank. Studies among other categories of people at risk for HTLV 1/2 infection should be carried out.

Origin and prevalence of human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) among indigenous populations in the Americas

Human T-lymphotropic virus type 1 (HTLV-1) is found in indigenous peoples of the Pacific Islands and the Americas, whereas type 2 (HTLV-2) is widely distributed among the indigenous peoples of the Americas, where it appears to be more prevalent than HTLV-1, and in some tribes of Central Africa. HTLV-2 is considered ancestral in the Americas and is transmitted to the general population and injection drug users from the indigenous population. In the Americas, HTLV-1 has more than one origin, being brought by immigrants in the Paleolithic period through the Bering Strait, through slave trade during the colonial period, and through Japanese immigration from the early 20^th century, whereas HTLV-2 was only brought by immigrants through the Bering Strait. The endemicity of HTLV-2 among the indigenous people of Brazil makes the Brazilian Amazon the largest endemic area in the world for its occurrence. A review of HTLV-1 in all Brazilian tribes supports the African origin of HTLV-1 in Brazil. The risk of hyperendemicity in these epidemiologically closed populations and transmission to other populations reinforces the importance of public health interventions for HTLV control, including the recognition of the infection among reportable diseases and events.

Seroepidemiology of human T-cell lymphotropic virus among Iranian adult thalassemic patients

BACKGROUND

A large number of transfusion-dependent thalassemic patients is at a substantial risk for transfusion-transmitted infections. Human T-cell lymphotropic virus (HTLV) is a blood-borne pathogen and can be transmitted via cellular products. We aimed to evaluate the seroprevalence of HTLV in transfusion-dependent thalassemic patients referred to Tehran Adult Thalassemia Clinic.

METHODS

From 2008 to 2010, 257 transfusion-dependent thalassemic patients who referred to Tehran Adult Thalassemia Clinic were enrolled. The seroprevalence of HTLV, hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV were assessed using enzyme-linked immunosorbant assay (ELISA). Also, the samples with positive result for anti-HTLVAb (by ELISA) were reassessed using Western blot for HTLV.

RESULTS

Among the 257 transfusion-dependent thalassemic patients who were tested for anti-HTLVAb, 29 (11.3%, 95% CI = 7.8-15.6%) were found to be anti-HTLVAb positive by ELISA and Western blot. No case was detected to be HBsAg positive, whereas 16% had HBV seroconversion criteria, and more than 95% had anti-HBsAb in their sera. Also, 103 (40.1%) patients were HCV seropositive, 13 (5.1%) patients of which were co-infected with HCV/HTLV. Among the HTLV-infected patients, 44.8% were co-infected with HCV, whereas 39.5% of HTLV-seronegative individuals were HCV mono-infected (P > 0.05).

CONCLUSION

This study showed that transfusion-dependent thalassemic patients were in higher risk for transmission of different blood-borne pathogens such as HTLV. The screening of HTLV in Iranian blood donors is recommended.

Characterization of overt and occult hepatitis B virus infection among HTLV-1 positive healthy carriers in the Northeast of Iran; AN HTLV-I endemic area

To date, no studies have provided data on hepatitis B virus (HBV) prevalence among asymptomatic, healthy human T-lymphotropic virus (HTLV-I) positive carriers. This sero- and molecular epidemiology study was performed on patients in the Northeast of Iran, which is an endemic area for HTLV-I infection. A total of 109 sera were collected from HTLV-I positive healthy carriers who were admitted to Ghaem Hospital, Mashhad City. All were tested for HBV serology and subsequently, real time PCR was carried out on the samples, regardless of the results of the serology. Standard PCR and direct sequencing were applied on positive samples. All cases were negative for HBsAg, Anti-HBc, and anti-HBs were positive in 34 (31.1%), and 35 (32%) individuals, respectively. There were 19 (17.4%) cases that were positive only for anti-HBs, and they had already received HBV vaccine. 16 (15%) were positive for both anti-HBs and anti-HBc, indicating a past-resolved HBV infection. 18 (16.5%) were isolated as anti-HBc, and 56 (51.3%) were negative for all HBV serological markers. Only one subject (0.9%) had detectable HBV DNA (2153 copy/ml), and assigned as being an occult HBV infection. The low prevalence of HBsAg, despite the high percentage of anti-HBc positive cases, might be related to the suppression effect of HTLV-I on surface protein expression. The low prevalence of HBV infection among HTLV-I positive healthy carriers from an endemic region, indicates that the epidemiology of HTLV-I and HBV coinfection is related to the endemicity of HBV in that region, rather than HTLV-I endemicity.

HIV-1 epidemic in Warao Amerindians from Venezuela: spatial phylodynamics and epidemiological patterns

OBJECTIVES

We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study was to evaluate the extent and the dynamic of HIV-1 dissemination in eight Warao communities.

DESIGN AND SETTING

HIV-1 infection was evaluated in 576 Warao Amerindians from the Orinoco Delta. Partial HIV-1 pol sequences were analyzed to reconstruct the spatiotemporal and demographic dynamics of the epidemic.

RESULTS

HIV-1 antibodies were present in 9.55% of Warao Amerindians, ranging from 0 to 22%. A significantly higher prevalence was found in men (15.6%) compared with women (2.6%), reaching up to 35% in men from one community. All but one isolates were classified as subtype B. Warao's HIV-1 subtype-B epidemic resulted from a single viral introduction at around the early 2000s. After an initial phase of slow growth, the subtype B started to spread at a fast rate (0.8/year) following two major routes of migration within the communities.

CONCLUSION

A dramatic high prevalence was documented in almost all the communities of Warao Amerindians from the Orinoco Delta tested for HIV-1 infection. This epidemic resulted from the dissemination of a single HIV-1 subtype B founder strain introduced about 10 years ago and its size is probably doubling every year, creating a situation that can be devastating for this vulnerable Amerindian group.

Human T cell lymphotropic virus type 2a strains among HIV type 1-coinfected patients from Brazil have originated mostly from Brazilian Amerindians

The human T cell lymphotropic virus type 2 (HTLV-2) is found mainly in Amerindians and in intravenous drug users (IDUs) from urban areas of the United States, Europe, and Latin America. Worldwide, HTLV-2a and HTLV-2b subtypes are the most prevalent. Phylogenetic analysis of HTLV-2 isolates from Brazil showed the HTLV-2a subtype, variant -2c, which spread from Indians to the general population and IDUs. The present study searched for the types of HTLV-2 that predominate among HIV-1-coinfected patients from southern and southeastern Brazil. Molecular characterization of the LTR, env, and tax regions of 38 isolates confirmed the HTLV-2c variant in 37 patients, and one HTLV-2b in a patient from Paraguay. Phylogenetic analysis of sequences showed different clades of HTLV-2 associated with risk factors and geographic region. These clades could represent different routes of virus transmission and/or little diverse evolutionary rates of virus. Taking into account the results obtained in the present study and the lack of the prototypic North American HTLV-2a strain and HTLV-2b subtypes commonly detected among HIV-coinfected individuals worldwide, we could speculate on the introduction of Brazilian HTLV-2 strains in such populations before the introduction of HIV.

HTLV-1 and -2 infections among 10 indigenous groups in the Peruvian Amazon

Infections with HTLV-1 and -2 were detected in 12 (1.9%) and 6 (0.9%) indigenous individuals living in 27 Amazonian villages in Peru. All infections occurred in Shipibo-Konibo people. HTLV was more common among participants living in villages distant from larger port cities and women with non-monogamous sexual partners.

Predominance of human lymphotropic T cell virus type 2 subtype B in urban populations of Argentina

Human T-lymphotropic virus subtype b (HTLV-2b) infection has been described among aborigines from Northern Argentina, while HTLV-2a has been described in an injecting drug user (IDU) from a Central region, similar to the situation in Spain, the United States, and Brazil. In this study, 22 of the 26 strains analyzed from blood donors and HIV-1(+) individuals were HTLV-2b (84.6%) clustering with Amerindian references, while 4 HIV-1(+) (15.4%) were HTLV-2a. HTLV-2a sequences were closely related to Brazilian references in contrast to the previous Argentinean IDU strain that clustered with Africans and Amerindians from North America. In summary, these findings show that HTLV-2b is the major strain circulating in an urban population of Argentina. HTLV-2a/b could have been introduced from endemic South American countries such as Brazil and because of contact with other populations such as IDUs from Europe despite its introduction due to the increasing internal migration of aborigines to large urban centers. Considering this results and recent data about the dissemination of HTLV-1 in residents of Buenos Aires city, new studies among non-at-risk groups for HTLV-1/2 infection should be performed.

Moderate prevalence of transmitted drug resistance and interiorization of HIV type 1 subtype C in the inland North State of Tocantins, Brazil

The diverse Brazilian AIDS epidemic has reached small cities and scant molecular information is available about the epidemic in Northern Brazil, where the incidence is growing. This study describes transmitted drug resistance and subtypes in the protease (PR) and reverse transcriptase (RT) regions among naive patients recruited in Palmas, the capital of Tocantins State, a newly built city in Northern Brazil. PR/RT regions were retrotranscribed from plasma HIV-1 RNA and 52 were sequenced after direct nested PCR. HIV-1 subtypes were assigned by phylogenetic analysis. Transmitted drug resistance was analyzed by the Calibrated Population Resistance tool Stanford Surveillance Drug Resistance Mutation. Most patients included (59.6%) were males, the median age was 30 years and were mainly referred because of heterosexual or homosexual unprotected sex. One male patient was from the Karajás indigenous tribe. The prevalence of transmitted resistance was 11.5% (CI 95%, 4.4-23.4%): nonnucleoside RT inhibitor mutations (n=3), nucleoside RT inhibitor mutations (n=2), and protease inhibitor mutations (n=1). Dual or triple class resistance was not observed. HIV-1 subtype B(PR)/B(RT) represented 78.8%, 5.8% were subtype C(PR)/C(RT), and 1.9% were subtype F1(PR)/F1(RT). Recombinant viruses represented 13.5% (07/52): B(PR)/F1(RT) (n=1), B(PR)/BF1(RT) (n=4), and C(PR)/CF1(RT) (n=2). This study about the AIDS epidemic in the recently founded city of Palmas/Tocantins in inland Northern Brazil shows moderate levels of transmitted drug resistance and the circulation of diverse recombinant viruses. This pattern is similar to what has been described in major metropolitan cities, suggesting the influence of imported cases from the south/southeast. Moreover these results indicate that patients from this setting should be monitored regarding transmitted drug resistance mutations.

Long terminal repeat sequence analysis of HTLV-2 molecular variants identified in Southern Brazil

In Brazil, human T-lymphotropic virus type 2 (HTLV-2) is endemic in Amerindians and epidemic in intravenous drug users (IDUs). The long terminal repeat (LTR) is the most divergent genomic region of HTLV-2, therefore useful to characterize subtypes. Nucleotide sequence and restriction fragment length polymorphism (RFLP) analysis of LTR genomic segments of fourteen HTLV-2 strains isolated from HIV-infected patients of Londrina, Southern Brazil, were carried out. Molecular analysis disclosed that all HTLV-2 strains belonged to 2a subtype, and RFLP detected the presence of the a4, a5, and a6 subgroups according to Switzer's nomenclature. RFLP correlated with nucleotide sequence, and phylogenetic analysis clustered HTLV-2 sequences of IDUs into subgroups a5 and a6. HTLV-2 sequences from individuals of sexual risk factor clustered into the a4 subgroup. These results extend the knowledge of the genetic diversity of HTLV-2 circulating in Brazil and provide insights into HTLV-2 transmission and virus movement in this geographic area.

Molecular epidemiology of HIV type 1 in northern Brazil: identification of subtypes C and D and the introduction of CRF02_AG in the Amazon region of Brazil

The molecular epidemiology of HIV-1 strains circulating in Belem-PA and Macapa-AP, in the Northern region of Brazil, is described using sequences of the C2V3 segment of the env and the pro gene of HIV-1 from patients of the Reference Unit for Special Infectious and Parasitary Diseases (URE-DIPE) in Belem-PA and the Central Laboratory (LACEN) in Macapa-AP. Subtype B was the most frequently found in relation to pro (88.3%) in Belem and in Macapa (97.1%) and env (88.3% in Belem and 100% in Macapa). Subtype F was also described in Belem (9.3% pro and 8.3% env) and Macapa (2.8% pro). Subtype D was described for the first time in the Northern region of the country as well as the recent entry of CRF02_AG. Furthermore, several possible recombinant forms among the various subtypes were found in both cities. The results support the hypothesis that HIV-1 infection is associated with the epidemic of the virus in the Southeast region of the country and that the city of Belem is the most important route for HIV-1 entry in the Northern region of Brazil.

Confirming the presence of HTLV-1 infection and the absence of HTLV-2 in blood donors from Arequipa, Peru

Epidemiological studies conducted in Peru disclosed HTLV-1 to be prevalent in different ethnic groups, and found HTLV-2 in some Amazonian Indians and in men who have sex with men. No data concerning HTLV-1/2 infection in blood donors from Arequipa, a highlands region in southern Peru, is available. We searched for the presence of HTLV-1 and HTLV-2 antibodies in 2,732 serum samples obtained from blood donors from this geographic area. HTLV-1/2-specific antibodies were detected using an enzyme-linked immunosorbent assay (ELISA) and were confirmed by Western blot (WB). Reactive sera had their blood bags discarded from donation, and the demographic characteristics of the donors were analyzed. Thirty-five sera (1.2%) were HTLV seroreactive by ELISA, and 25 were confirmed HTLV-1-positive by WB. One serum disclosed HTLV-positivity, and the remaining nine serum samples showed indeterminate results by WB; three of which had an HTLV-1 indeterminate Gag profile. The median age of HTLV-positive individuals was 34.6 years; 27 were male and eight were female. All individuals were from southern Peru: 27 from Arequipa, five from Puno, and three from Cuzco. HTLV co-positivity with hepatitis B (five sera) and syphilis (one serum) were detected. Previous transfusion and tattooing were observed in two and one individuals, respectively. No serum was positive for HTLV/HIV co-infection. This study confirmed, for the first time, HTLV-1 infection and the absence of HTLV-2 infection in blood donors from Arequipa, Peru and suggests vertical transmission as the major route of HTLV-1 transmission and acquisition in this geographic region.

Frequency distribution of XbaIG > T and HaeIIIT > C GLUT1 polymorphisms among different Brazilian ethnic groups

GLUT is the major glucose transporter in mammalian cells. Single nucleotide polymorphisms (SNP) at GLUT1 promoter and regulatory regions have been associated to the risk of developing nephropathy in different type 1 and type 2 diabetic populations. It has been demonstrated that differences in allelic and genotypic frequencies of GLUT1 gene (SLC2A1) polymorphisms occur among different populations. Therefore, ethnic differences in distribution of GLUT1 gene polymorphisms may be an important factor in determining gene-disease association. In this study, we investigated the XbaIG > T and HaeIIIT > C polymorphisms in six different Brazilian populations: 102 individuals from Salvador population (Northern Brazil), 56 European descendants from Joinville (South Brazil), 85 Indians from Tiryió tribe (North Brazil) and 127 samples from Southern Brazil: 44 from European descendants, 42 from African descendants and 41 from Japanese descendants. Genotype frequencies from both sites did not differ significantly from those expected under the Hardy-Weinberg equilibrium. We verified that the allele frequencies of both polymorphisms were heterogeneous in these six Brazilian ethnic groups.

Phylogenetic and molecular analysis of HTLV-1 isolates from a medium sized town in northern of Brazil: tracing a common origin of the virus from the most endemic city in the country

Salvador-Bahia has the highest prevalence of HTLV-1 infection in Brazil; about 2% of the population is infected. In this city, the prevalence of HTLV in pregnant women is 1%. There is no data of the HTLV-1 prevalence in others cities of the Bahia's Recôncavo, where the population has similar social and demography characteristics to those from Salvador. Our aim was to evaluate the seroprevalence of HTLV in pregnant women in Cruz das Almas-Bahia, a medium-sized city from the Bahia's Recôncavo. All individuals were tested for HTLV (ELISA) and the positive samples were confirmed by Western Blot. Phylogenetic analyses of the total LTR region were performed in all positive samples. We tested 408 samples (45.4% of the estimate pregnant women population) between June 1st and October 31, 2005. The prevalence of HTLV-1 infection was 0.98%. In addition, all isolated virus were grouped in the subtype HTLV-1a, in the Latin American group. Our results suggest that the introduction of HTLV-1 occurred after the slave trade into Salvador. In addition, HTLV-1-infection should be screened during the pregnancy in women originating from HTLV-1 endemic areas.

Serological patterns and temporal trends of HTLV-1/2 infection in high-risk populations attending Public Health Units in São Paulo, Brazil

BACKGROUND

HTLV-1/2 diagnosis in high-risk populations from São Paulo, Brazil has been problematic due a high proportion of seroindeterminate results.

OBJECTIVES

To confirm and extend previous findings regarding HTLV-1/2 diagnosis in this geographic area.

STUDY DESIGN

Sera from 2312 patients were tested for HTLV-1/2 antibodies using enzyme immunoassay (EIA) and Western blot (WB) analysis. Patients were from AIDS Reference Centers (Group I; 1393 patients) and HTLV out-patient clinics (Group II; 919 patients). Results were analyzed according to patients' age, gender, and clinic type.

RESULTS

HTLV-1 and HTLV-2 were detected in both groups. Among seropositive females, HTLV-2 was slightly more common in Group I (54.5%), while HTLV-1 prevailed in Group II (73.9%). Males from Group II had a higher percentage of HTLV-seroindeterminate results. No correlation between HTLV serological results and age was detected. Temporal analyses disclosed a high number of HTLV-seroindeterminate samples, and a large spectrum of indeterminate WB profiles. GD21 and/or rgp46-II bands were detected in 34.6% of sera from Group I, and a p24 or p19 band was detected in 35.3% of sera from Group II.

CONCLUSIONS

High rates of HTLV-indeterminate serological patterns during temporal analyses were confirmed in high-risk populations from São Paulo, Brazil.

Difficulties in the diagnosis of HTLV-2 infection in HIV/AIDS patients from Brazil: comparative performances of serologic and molecular assays, and detection of HTLV-2b subtype

The current diagnosis of human T-lymphotropic virus type-2 (HTLV-2) infection is based on the search of specific antibodies; nevertheless, several studies conducted in Brazil pointed deficiencies of the commercially available kits in detecting HTLV-2, mostly in HIV/AIDS patients. This study searched for the presence of HTLV-1 and -2 in 758 HIV/AIDS patients from Londrina, Paraná, Brazil. Serum samples were screened for HTLV-1/2 antibodies using two EIA kits (Vironostika and Murex), and confirmed by WB (HTLV Blot 2.4, Genelabs). The results obtained by EIA disclosed 49 (6.5%) reactive sera: 43 positive by both EIA kits, and six with discordant results. WB confirmed HTLV-1 infection in seven samples (0.9%) and HTLV-2 in 21 sera (2.8%). Negative and indeterminate results were detected in four (0.5%) and 16 (2.1%) sera, respectively. Blood from 47 out of 49 HTLV seroreactive patients were collected and analyzed for the presence of env, LTR and tax genomic segments of HTLVs by PCR. PCR confirmed six cases of HTLV-1 and 37 cases of HTLV-2 infection (14 out of 16 that were found to be WB indeterminate). Restriction analysis of the env PCR products of HTLV-2 disclosed 36 isolates of HTLV-2a/c subtype, and one of HTLV-2b subtype. These results emphasize the need of improving serologic tests for detecting truly HTLV-2 infected patients from Brazil, and confirm the presence of HTLV-2b subtype in the South of this country.

Unusual finding of HTLV-I infection among Amazonian Amerindians

Human T-cell lymphotropic virus type II is a retrovirus endemic in Amerindian communities throughout the American continent, although some Amerindian groups that apparently emerged from the same ethnic root as HTLV-II carriers do not secrete antibodies against the virus and show very low prevalence for human T-cell lymphotropic virus type I. In this study, sera from 487 Amazonian amerinds were screened for HTLV type I and II antibody by the gelatin particle agglutination assay and ELISA and confirmed by Western blot and indirect immunofluorescence assay. None was positive for HTLV type II. One young healthy male of Waiãpi ethnicity was reactive with HTLV-I and was confirmed by Western blot assay and indirect immunofluorescence test. The absence of HTLV type II infection among these Amerindian communities would suggest a behavior pattern distinct from other groups in the American continent. Also, the very low prevalence of HTLV type I infection among these ethnic groups probably indicates contamination by blood transfusion (external transmission route).

Patterns of In vitro Lymphoproliferative Responses Among HTLV-1-infected Subjects: Upregulation by HTLV-1 During HIV-1 Co-infection

The present study evaluated the in vitro response to different mitogens and a candidin antigen (CMA) in Human T-cell lymphotropic virus type 1 (HTLV-1) and co-infected HIV-1/HTLV-1 patients, to identify if this co-infection may modify the spontaneous lymph proliferative response. Peripheral blood mononuclear cells from 72 healthy seronegative controls, 75 asymptomatic HTLV-1-infected carriers, 42 HAM/TSP cases, 33 solely HIV-1-infected subjects and 24 HIV-1/HTLV-1 patients were assayed in the presence and absence of mitogens (PHA, PWM and OKT3) and CMA. The HAM/TSP group had the highest proliferation rate at 3 and 6 days after culture. HAM/TSP cases showed decreased response to PHA, compared with asymptomatic HTLV-1 subjects, and most important, the co-infected HIV-1/HTLV-1 cases presented a similar response to HTLV-1-infected subjects after 3 days of culture. The singles HIV-1-infected group had decreased in vitro response. It appears that during co-infection, the HTLV-1 regulatory proteins overwhelm the action of HIV-1 regulatory proteins.

Serological and molecular typing of HIV type 1 infection in the Tiriyo tribe, a native Indian community of the Amazon region of Brazil

The seroprevalence and the occurrence of an HIV-1 subtype was assessed in blood samples of the Tiriyo tribe. Antibody was found in 0.6% and the molecular analysis of the pro region detected the emergence of a subtype B for the first time in a native Indian tribe of the Amazon region of Brazil.

Molecular evidence of HTLV-II subtype B among an urban population living in South Brazil

Human T cell lymphotropic virus type II (HTLV-II) is a deltaretrovirus endemic in Indian populations living in Central and South America, among Pygmies tribes from Central Africa, and epidemic among injecting drug users (IDUs) in the United States, Europe, Southeast Asia, and South America. To date only the HTLV-IIa subtype has been demonstrated among Brazilians (Amazon basin Indians, blood donors, and IDUs). We analyzed HTLV-II isolates from 12 individuals living in the urban area of Porto Alegre, Southern Brazil, identified as seropositive for HTLVI/II in a blood donation. The HTLV-II long terminal repeat (LTR) region was sequenced and compared with nucleotide sequences of isolates HTLV-IIa (Mo), HTLV-IIb (NRA) prototypes. Phylogenetic analysis of the LTR region demonstrated that seven new isolates clustered together with American Indians HTLV-IIb isolates, and five new HTLV-IIa isolates clustered within the HTLV-IIa Brazilian subgroup, named the HTLV-IIc subtype. Both HTLV-IIa and IIb seem to be endemic in the urban area of Porto Alegre, South of Brazil, and could have reached this region via the Amazon basin and the Pacific Coast ancient human migratory pathways. To our knowledge this is the first study demonstrating the presence of HTLV-IIb among the urban population in Brazil.

Molecular characterization of human T-cell lymphotropic virus type 2 (HTLV-II) from people living in urban areas of Sao Paulo city: Evidence of multiple subtypes circulation

BACKGROUND

In Brazil, human T-cell lymphotropic virus type I and type II (HTLV-I and HTLV-II) are co-circulating and possess approximately 65% homology, which results in high cross-reactivity in serological tests. Based on the detection of EIA and Western blot (WB) tests, HTLV serodiagnosis yields indeterminate results in high-risk population, with the true determination of HTLV-II prevalence requiring a combined serological and molecular analysis. Molecular analysis of HTLV-II isolates has shown the existence of four distinct subtypes: IIa, IIb, IIc, and IId. The aim of this study was to evaluate the routine EIA and WB used in Sao Paulo city, as well as molecular methods for confirmation of infection and HTLV-II subtype distribution.

RESULTS

Two hundred ninety-three individuals, who were enrolled in the HTLV out-clinic in Sao Paulo city, Brazil, between July 1997 and May 2003, were tested by EIAs, and positive sera 232 (79%) reactive by one of the tests. When these sera were tested by WB revealed 134 were HTLV-I, 28 HTLV-II, 4 HTLV-I/II, and 48 were indeterminate. Polymerase chain reaction (PCR) on the indeterminate group showed that 20 (42%) were HTLV-II and 28 were negative. From a total of 48 HTLV-II subjects with DNA available, restriction fragment length polymorphism (RFLP) of the env region revealed 47 HTLV-IIa and 1 HTLV-IIb. The phylogenetic analysis was performed on 23 samples, which identified 19 as subtype a, Brazilian subcluster, and 4 as subtype b. This is the first time HTLV-II subtype b has been described in Brazil. However, further studies, such as a complete nucleotide DNA sequencing, need to be done to confirm these findings.

HUMAN RIGHTS, BIOMEDICAL SCIENCE, AND INFECTIOUS DISEASES AMONG SOUTH AMERICAN INDIGENOUS GROUPS

Despite the efforts of international health agencies to reduce global health inequalities, indigenous populations around the world remain largely unaffected by such initiatives. This chapter reviews the biomedical literature indexed by the PubMed database published between 1963 and 2003 on South American indigenous populations, a total of 1864 studies that include 63,563 study participants. Some language family groupings are better represented than are others, and lowland groups are better represented than are highland groups. Very few studies focus on major health threats (e.g., tuberculosis, influenza), public health interventions, or mestizo-indigenous epidemiological comparisons. The prevalence rates of three frequently studied infections—parasitism, human T-cell lymphotropic viral infection (HTLV), and hepatitis—are extraordinarily high, but these facts have been overlooked by national and international health agencies. This review underscores the urgent need for interventions based on known disease prevalence rates to reduce the burden of infectious diseases in indigenous communities.

Increasing seroprevalence of Human herpesvirus 8 (HHV-8) with age confirms HHV-8 endemicity in Amazon Amerindians from Brazil

Human herpesvirus 8 (HHV-8) seroprevalences were determined in two isolated Amazon Amerindian tribes, according to age, gender and familial aggregation. Plasma and serum samples obtained from 982 Amazon Amerindians (664 Tiriyó and 318 Waiampi) were tested for antibodies against lytic and latent HHV-8 antigens by using ‘in-house’ immunofluorescence assays. Overall, HHV-8 seroprevalence was 56·8 % (57·4 % in the Tiriyó tribe and 55·7 % in the Waiampi tribe). Seroprevalence was independent of gender and increased linearly with age: it was 35·0 % among children aged 2–9 years, 51·4 % in adolescents (10–19 years), 72·9 % in adults and 82·3 % in adults aged >50 years. Interestingly, 44·4 % of children under 2 years of age were HHV-8-seropositive. No significant differences in seroprevalence between tribes and age groups were detected. It is concluded that HHV-8 is hyperendemic in Brazilian Amazon Amerindians, with vertical and horizontal transmission during childhood, familial transmission and sexual contact in adulthood contributing to this high prevalence in these isolated populations.

In vitro photochemical inactivation of cell-associated human T-cell leukemia virus Type I and II in human platelet concentrates and plasma by use of amotosalen

BACKGROUND

Human T-cell leukemia virus Types I and II (HTLV-I and HTLV-II), blood-borne retroviruses found worldwide, can cause leukemia, immunosuppression, and severe neurologic diseases. In most countries, HTLV-I and -II screening is not performed systematically for blood donations. A new photochemical treatment (PCT) with a synthetic psoralen was developed to inactivate most pathogens in platelet (PLT) concentrates or plasma and to improve the safety of blood donations.

STUDY DESIGN AND METHODS

Cell-associated HTLV-I or -II (10(6)/mL) was inoculated in full-size fresh PLT concentrates or fresh frozen plasma and treated with 150 micromol per L amotosalen (S-59) and different doses of long-wavelength ultraviolet A (UVA) light. The residual viral titer in the treated samples was assessed by a cocultivation assay on indicator cells.

RESULTS

The inactivation obtained at a 3.0 J per cm2 UVA dose was greater than 5.2 log foci-forming units (FFUs) per mL for HTLV-I and 4.6 log FFUs per mL for HTLV-II in presence of human PLT concentrates and greater than 4.5 log FFUs per mL for HTLV-I and 5.7 log FFUs per mL for HTLV-II in the presence of human plasma. The residual infectivity was very low and shown as the limit of detection of the cocultivation assay.

CONCLUSION

In human plasma or PLT concentrates, the retroviruses HTLV-I and -II were strongly sensitive to the PCT with 150 micromol per L amotosalen (S-59) and a 3.0 J per cm2 UVA dose. This high efficiency for photoinactivation of these retroviruses opens a possibility of improving the safety of PLTs or plasma transfusion in the future.

Molecular characterization of human T-cell lymphotropic virus coinfecting human immunodeficiency virus 1 infected patients in the Amazon region of Brazil

The present work evaluated the epidemiology of human immunodeficiency virus 1/human T-cell lymphotropic virus (HIV-1/HTLV) coinfection in patients living in Belém (state of Pará) and Macapá (state of Amapá), two cities located in the Amazon region of Brazil. A total of 169 blood samples were collected. The sera were tested by enzyme-linked immunosorbent assay to determine the presence of antibodies anti-HTLV-1/2. Confirmation of infection and discrimination of HTLV types and subtypes was performed using a nested polymerase chain reaction targeting the pX and 5' LTR regions, followed by restriction fragment length polymorphism and sequencing analysis. The presence of anti-HTLV1/2 was detected in six patients from Belém. The amplification of the pX region followed by RFLP analysis, demonstrated the presence of HTLV-1 and HTLV-2 infections among two and four patients, respectively. Sequencing HTLV-1 5' LTR indicated that the virus is a member of the Cosmopolitan Group, Transcontinental subgroup. HTLV-2 strains isolated revealed a molecular profile of subtype HTLV-2c. These results are a reflex of the epidemiological features of HIV-1/HTLV-1/2 coinfection in the North region of Brazil, which is distinct from other Brazilian regions, as reported by previous studies.

HTLV-2 horizontal and vertical transmission in a family from a Brazilian urban area: seroepidemiological, clinical and molecular study

Human T cell lymphotropic virus type 2 (HTLV-2) has been shown to be endemic in Brazilian Indians and among intravenous drug users in urban areas, but transmission of this infection seems to be infrequent in the general population living in urban areas in Brazil. Six persons in three generations of a Brazilian family were evaluated to assess HTLV-2 transmission and its molecular features in the positive cases. The index was detected during screening (HTLV EIA) of donated blood in Fundação Hemominas, Belo Horizonte, Brazil. Confirmatory serological test and viral typing were performed by Western blotting and polymerase chain reaction. The family consisted of husband, wife (index case), three daughters, and the mother of the index case. The husband and one daughter were found positive, thus pointing to horizontal and vertical transmission. The husband was a truck driver, who reported casual sex during frequent traveling. The positive daughter was breast-fed for 3 months, as opposed to the remaining two (seronegative), who breast-fed for 1 month. The index case's mother was negative. To identify HTLV-2 subtype(s), phylogenetic analysis of the noncoding long terminal repeat region and part of the env and tax coding regions was performed. These new isolates from Belo Horizonte are related to subtype IIa but present a molecular variant with extended tax, previously reported in subtype IIc. Analyzing both LTR and env regions, the family's sequences clustered with isolates of Brazilian intravenous drug users and transfusion transmitted virus.

High seroprevalence of human T-cell lymphotropic virus type 1 in blood donors in Guyana and molecular and phylogenetic analysis of new strains in the Guyana shelf (Guyana, Suriname, and French Guiana)

The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 in blood donors in Guyana has never been estimated. We evaluated the prevalence of these viruses in blood donors by enzyme-linked immunosorbent assay and Western blotting and showed a prevalence of HTLV-1 of 1.3%; no HTLV-2 was detected. Female donors had a much higher HTLV-1 seroprevalence (3.6%) than male donors (0.7%). HTLV-1-seropositive donors tended to be slightly older than the average age for the total pool of donors. We also investigated the phylogenetic and molecular characteristics of HTLV-1 strains in Guyana and compared them with those identified in Suriname and French Guiana. Analysis of portions of the env and long terminal repeat nucleotide sequences showed that all the strains in Guyana and Suriname, like those in French Guiana, belonged to the transcontinental group of cosmopolitan subtype A. The similarities were greater between strains from Suriname and Guyana than between strains from Suriname and Guyana and those from French Guiana. Nevertheless, our results confirm that the HTLV-1 strains in all three countries have a common African origin.

High prevalence of human T-lymphotropic virus type 1 (HTLV-1) in immigrant male-to-female transsexual sex workers with HIV-1 infection

Human T-lymphotropic virus type 1 and 2 (HTLV-1 and HTLV-2) infections in Europe are limited to intravenous drug users and migrants coming from areas in which they are endemic. A survey was undertaken of HTLV-1 and HTLV-2 infections in 393 recent immigrants: 167 HIV-1 positive subjects (including 52 male-to-female transsexual sex workers) and 226 pregnant HIV-1 negative women. The prevalence of HTLV-1 was 3.6% in the HIV-1 positive group and 0.9% in the HIV-1 negative group. The highest HTLV-1 prevalence in both groups was found in persons from Latin America, particularly those born in Peru (up to 26% in the HIV-1 positive group). All of the HIV-1/HTLV-1 co-infected individuals were male-to-female transsexual sex workers in whom the overall prevalence of HTLV-1 infection was 11.5%. HTLV-2 was only found in the HIV-1 positive group (prevalence 1.2%); all of the infected subjects were transsexual sex workers from Brazil (overall prevalence 6.4%). Phylogenetic analysis showed that all of the HTLV-1 isolates were of the cosmopolitan type, clustering with other strains circulating in the patients' birthplaces; the HTLV-2 isolates were of subtype 2a, and clustered significantly with other Brazilian strains. These results suggest the independent origin of each infection in the patient's birthplace. The data raise concerns about the further spread of HTLV infections mainly through the sexual route.

Human T-cell Lymphotropic Virus types I and II (HTLV-I/II) in French Guiana: clinical and molecular epidemiology

We review here the epidemiological studies performed by our group on human retrovirus HTLV-I and HTLV-II infections and the associated diseases in French Guiana since 1984. French Guiana is an overseas French administrative district located between Brazil and Surinam. Its population is characterized by a large variety of ethnic groups, including several populations of African origin and various populations of Amerindian origin. Several epidemiological studies of large samples of pregnant women and in remote villages showed that HTLV-I is highly endemic in this area but is restricted to groups of African origin, especially the Noir-Marrons. In this endemic population, the results of segregation analysis in a genetic epidemiological study were consistent with the presence of a dominant major gene predisposing to HTLV-I infection, especially in children. In contrast, HTLV-II infection appears to be rare in French Guiana, having been found in only a few individuals of Brazilian origin. From a molecular point of view, the HTLV-I strains present in the Noir-Marrons, Creoles and Amerindians appear to originate from Africa, as they belong to the large cosmopolitan molecular subtype A.

Prevalência da infecção pelo vírus linfotrópico humano de células T e fatores de risco associados à soropositividade em doadores de sangue da cidade de Rio Branco, AC, Brasil (1998-2001)

Para cada doador de sangue soropositivo (ELISA, Abbott®) para HTLV-I/II, de dezembro de 1998 a março de 2001, também foram selecionados dois soronegativos. As amostras séricas foram re-testadas pelo ELISA (Murex®) e aquelas que permaneceram soropositivas foram testadas pelo Western Blot e pela PCR. Das 11.121 amostras séricas, 73 (0,66%) foram positivas (Abbott®), mas somente 12 (0,11%) permaneceram positivas (Murex®), enquanto que as 146 soronegativas foram confirmadas, apesar de ser sofrível o índice de concordância entre os dois ELISA. O Western Blot confirmou as 12 amostras como soropositivas: 8 (0,07%) HTLV-I; duas (0,02%) HTLV-II e duas (0,02%) indeterminadas - sendo pela PCR uma pelo HTLV-I e a outra pelo HTLV-II. Em conclusão, nessa população da Amazônia Ocidental foi muito baixa a soroprevalência de HTLV-I/II, apesar de ser esperada maior prevalência do HTLV-II devido a grande miscigenação racial indígena.

Epidemiological aspects of retrovirus (HTLV) infection among Indian populations in the Amazon Region of Brazil

HTLV was initially described in association with a form of leukemia in Japan and a neurological disease in the Caribbean. It was soon shown that HTLV-II was endemic among Amerindians and particularly among Brazilian Indians. The Amazon Region of Brazil is presently the largest endemic area for this virus and has allowed several studies concerning virus biology, the search for overt disease, epidemiological data including detailed demographic data on infected individuals, clear-cut geographic distribution, definition of modes of transmission and maintenance within small, epidemiologically-closed groups, and advances in laboratory diagnosis of the infection. A new molecular subtype named HTLV-IIc was further described on the basis of genome sequencing and phylogenetic analysis. This subtype is present in other areas of Brazil, indicating that the virus is additionally both a valuable marker for tracing past human migration routes in the Americas and a probable marker for social habits of the present human population. HIV, the other human retrovirus, is still not prevalent among indigenous communities in the Brazilian Amazon, but these groups are also easy targets for the virus.

Brazilian HTLV type 2a strains from intravenous drug users (IDUs) appear to have originated from two sources: Brazilian Amerindians and European/North American IDUs

In Brazil, HTLV-2 has been detected in blood donors, in intravenous drug users (IDUs) from urban areas, and in Amerindians living in the Amazon basin. Of the three main HTLV-2 subtypes (2a, 2b, and 2d) only subtype 2a has been detected in Brazil. However, a molecular variant of subtype 2a (also called HTLV-2c) characterized by an extended Tax protein has been isolated from Brazilian blood donors, IDUs, and Indians. Here, we analyzed HTLV-2 isolates from 10 IDUs and a Chilean woman living in Salvador, Bahia, Brazil. Sequencing of env, pX, and long terminal repeat (LTR) genes demonstrated that 10 of the isolates are related to the Brazilian subtype 2a molecular variant described previously. We show that most HTLV-2a Brazilian strains comprise a phylogenetic group harboring a considerable degree of diversity within the env region but not within the LTR region. Interestingly, we demonstrated for the first time in Brazil the presence of a subtype 2a in IDUs that is closely related to the prototype Mo but distinct from the Brazilian 2a molecular variant.