Isolation and genomic analysis of human T lymphotropic virus type II from Ghana

HTLV-2B strains, similar to those found in several Amerindian tribes, are endemic in central African Bakola Pygmies

BACKGROUND

The presence and origin of endemic foci of human T-lymphotropic virus type 2 (HTLV2) infection in Africa remain a matter of debate.

METHODS

To better appreciate such determinants, we performed a survey of 1918 inhabitants from Cameroon forest areas, including 1051 Bakola Pygmies and 867 Bantus.

RESULTS

The overall HTLV-1/2 seroprevalence was 4% (49 cases of HTLV-1 and 27 cases of HTLV-2 infection). Both infections were mainly restricted to the Bakola Pygmies, with surprisingly no HTLV-2 infections in the Bantu population. Both HTLV-1 and HTLV-2 seroprevalences increased with age. There was evidence of ongoing HTLV-2 transmission in this population. Lymphoid T cell lines producing HTLV-2 were established. HTLV-2 long terminal repeat sequences (672 base pairs) obtained from 7 infected Bakola were highly similar to each other (<1% nucleotide divergence), as well as to Amerindian HTLV-2B strains. Analyses on a complete sequence (8954 base pairs) confirmed that it was a typical HTLV-2 subtype B strain. Along with molecular clock analysis, these data strongly suggest that HTLV-2 has been endemic in the Bakola Pygmy population for a long time.

CONCLUSIONS

This study demonstrates clearly an HTLV-2 endemicity with ongoing transmission in an African population. Furthermore, it give insights into central questions regarding the origins and evolution rate of HTLV-2 and the migrations of infected populations.

Seroepidemiological and molecular studies of human T cell lymphotropic virus type II, subtype b, in isolated groups of Mataco and Toba Indians of northern Argentina

We studied plasma samples from 2082 Mataco Indians living in 22 different communities in the western part of Formosa Province, northern Argentina. Samples were screened for HTLV-I/II antibodies by particle agglutination assay. All positive or borderline samples were then tested by an immunofluorescence assay (IFA) on C19 HTLV-II-producing cells. Western blot was used for confirmation of all IFA-positive plasma samples. The crude HTLV-II seroprevalence was 3.0% (62 of 2051), and 0.9% (5 of 588) in children less than 10 years old. The latter result suggests ongoing mother-to-child transmission, probably by breast feeding. There was a marked increase in HTLV-II seroprevalence with age (0.9%, 0-10 years; 1.6%, 11-20 years; 4.4%, 21-30 years; 3.4%, 31-40 years; 7.2%, 41-50 years; 5.7%, >50 years) in both male (p = 0.002) and female subjects (p = 0.00002). None of the 80 non-Indian inhabitants tested was HTLV-I/II seropositive. In a second study, among 105 Toba Indians from a village (Primavera) of the eastern part of this region, 23 were HTLV-II seropositive with a seroprevalence of 59% in those more than 40 years old. From seven of the Indians from Primavera, three others from neighboring regions (including two Tobas and one Pilaga), and one intravenous drug user (IVDU) from Rosario, DNA was extracted from peripheral blood mononuclear cells, and the gp21 transmembrane-encoding gene (590 bp) was amplified by PCR, cloned, and sequenced. LTR sequences were also obtained from the Pilaga, the IVDU, and one Toba. Molecular and phylogenetic analyses revealed that the Indians were all infected with closely related HTLV-II molecular strains belonging to the b subtype, while the IVDU was infected with an HTLV-II subtype a variant. Such data help to make a phylogenetic atlas of HTLV-II among Amerindian tribes and are crucial to gain new insights into the origin and modes of dissemination of this human retrovirus in the Americas.

African origin of human T-lymphotropic virus type 2 (HTLV-2) supported by a potential new HTLV-2d subtype in Congolese Bambuti Efe Pygmies

We identified a potential new subtype within human T-cell lymphotropic virus type 2 (HTLV-2), HTLV-2d, present in members of an isolated Efe Bambuti Pygmy tribe. Two of 23 Efe Pygmies were HTLV-2 seropositive, with HTLV-2 Western blot and enzyme-linked immunosorbent assay reactivities. From one of them the entire genome of the HTLV-2 strain Efe2 could be amplified and sequenced. In all gene regions analyzed, this strain was the most divergent HTLV-2 strain, differing by 2.4% (tax/rex) to 10.7% (long terminal repeat) from both subtypes HTLV-2a and HTLV-2b, yet major functional elements are conserved. The similarity between the HTLV-2 Efe2 Gag and Env proteins and the corresponding HTLV-2a and -2b proteins is consistent with the observed serological reactivity. In the proximal pX region, one of the two alternative splice acceptor sites is abolished in HTLV-2 Efe2. Another interesting feature of this potential new subtype is that it has a Tax protein of 344 amino acids (aa), which is intermediate in length between the HTLV-2a Tax protein (331 aa) and the HTLV-2b and -2c Tax proteins (356 aa) and similar to the simian T-cell lymphotropic virus type 2 (STLV-2) PP1664 Tax protein. Together these two findings suggest a different phenotype for the HTLV-2 Efe2 strain. Phylogenetic analyses confirmed that the Pygmy Efe2 strain potentially belonged to a new and quite divergent subtype, HTLV-2d. When the STLV-2 bonobo viruses PP1664 and PanP were used as an outgroup, it was clear that the Pygmy HTLV-2 Efe2 strain had the longest independent evolution and that HTLV-2 evolution is consistent with an African origin.

The origin and evolution of human T-cell lymphotropic virus types I and II

Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II.

Molecular epidemiology of HTLV-II among United States blood donors and intravenous drug users: an age-cohort effect for HTLV-II RFLP type aO

Molecular subtyping was used to investigate the epidemiology of human T-lymphotropic virus type II (HTLV-II) in the United States. Nested polymerase chain reaction of the HTLV-II long terminal repeat region followed by restriction fragment length polymorphism (RFLP) analysis was performed on HTLV-II seropositive subjects including 97 U.S. blood donors without major risk factors for HTLV-II infection, 53 injection drug users (IDU), and 10 American Indian blood donors. Three new HTLV-II RFLP types were confirmed with DNA sequencing and phylogenetic analysis. HTLV-II RFLP type aO (Switzer classification) was associated with older age [adjusted odds ratio (OR) 1.06 per year of age, 95% confidence interval (CI) 1.02-1.09] and with Black (OR 5.24, 95% CI 1.90-14.47) and White (OR 4.43, 95% CI 1.67-11.75) race/ethnicity. These data are consistent with an age-cohort effect for HTLV-II RFLP type aO among older White and Black IDU and blood donors. This finding could be explained by an epidemic of non-aO HTLV-II RFLP types among younger persons of Hispanic and other race/ethnicity, superimposed upon endemic HTLV-II RFLP type aO among older Black and White persons.

Molecular phylogeny of human T-cell leukemia virus type I and II of Amerindians in Colombia and Chile

Six human T-cell leukemia virus type I (HTLV-I) and eight human T-cell leukemia virus type II (HTLV-II) cases newly isolated from the South American countries of Colombia and Chile were analyzed together with the two Amerindian HTLV-I isolates previously reported. All of the HTLV-I isolates belonged to the transcontinental subgroup of the "cosmopolitan" group, and Colombian isolates, including those from native Amerindians and Negroes, formed a single tight cluster within this subgroup. The transcontinental subgroup consisted of isolates from various regions such as the Caribbean basin, India, Iran, South Africa, Sakhalin, and Japan, and included isolates from the "Ainu" and "Okinawa" people, regarded as relatively pure Japanese descended from the prehistoric "Jomon" period which began more than 10,000 years ago. This implied a dissemination of the subgroup associated with the movement of human beings in ancient times. On the other hand, all of the HTLV-II isolates from native Amerindians in Colombia and Chile belonged to the HTLV-IIb subtype which has previously been reported to be mainly endemic in certain populations of native Amerindians. The southernmost isolate from Chile, showing wide distribution of the IIb subtype in native South Amerindians and largest heterogeneity of the subtype in Colombian isolates, supported the idea that the HTLV-IIb subtype has been endemic for a long time in native Indians of South America.

Nucleotide sequence and restriction fragment-length polymorphism analysis of human T-cell lymphotropic virus type II (HTLV-II) in southern Europe: evidence for the HTLV-IIa and HTLV-IIb subtypes

Human T-cell lymphotropic virus type II (HTLV-II) has been subtyped into two major groups, IIa and IIb, according to molecular studies involving env gene sequencing. Subsequently, this retrovirus was further subclassified by examining the long terminal repeat (LTR), the most divergent genomic region. Sequence analysis and restriction fragment-length polymorphism (RFLP) applied to the LTR region identified either four or five groups within the IIa subtype (depending on the restriction enzyme sets used) and six within the IIb subtype. In this study, we analyzed the LTR sequences of 29 samples obtained from HTLV-II-infected individuals living in Spain and Italy, which included 24 injecting drug users (IDUs), three blood donors, and two subjects at risk for HIV/HTLV infection. Sequence analysis and phylogenetic analysis of 720 base pairs of the LTR performed in 10 Spanish samples showed that all of these samples belonged to IIb subtype, with a divergence of 7.5% and 1.66% compared with MoT (IIa) and NRA/G12 (IIb) isolates, respectively. RFLP analysis demonstrated the presence of the IIb 4-subtype restriction pattern in 26 samples, a IIb5-subtype pattern in one Italian IDU, and a IIa0-subtype pattern in two Italian samples (blood donors), according to W.M. Switzer's nomenclature. This is the first report of the presence of IIb5 in Southern Europe and IIa0 among Italian blood donors. RFLP correlated with nucleotide sequence and phylogenetic data obtained in this study, demonstrating the ability of the RFLP method to predict the phylogroup of HTLV-II-infected samples.

Mother-to-child transmission of human T-cell lymphotropic virus types I and II (HTLV-I/II) in Gabon: a prospective follow-up of 4 years

SUMMARY

For 4 years. we determined the mode and risk of mother-to-child transmission of HTLV-I in a prospective cohort of 34 children born to seropositive mothers in Franceville, Gabon. We also determined the prevalence of antibodies to HTLV-I/II in siblings born to seropositive mothers. Antibodies to HTLV-I/II were detected by Western blot, and the proviral DNA was detected by the polymerase chain reaction (PCR). The risk of seroconversion to anti-HTLV-I for the 4 years of follow-up was 17.5 percent. Anti-HTLV-I/II and proviral DNA were only detected after age 18 months. We observed a seroprevalence rate of 15 percent among the siblings born to HTLV-I/II seropositive mothers. Furthermore, we report a case of mother-to-child transmission of HTLV-II infection in a population of HTLV-II-infected pregnant women that is emerging in Gabon. The lack of detection of HTLV-I/II proviral DNA in cord blood and amniotic fluid and, furthermore, the late seroconversion observed in the children indirectly indicate that mother-to-child transmission occurred postnatally, probably through breast milk.

Endemicity and phylogeny of the human T cell lymphotropic virus type II subtype A from the Kayapo Indians of Brazil: evidence for limited regional dissemination

Long terminal repeat (LTR)-based restriction fragment length polymorphism (RFLP) analysis of human T cell lymphotropic virus type II (HTLV-II) from 17 seropositive Kayapo Indians from Brazil showed that all 17 samples contained a unique HTLV-IIa subtype (A-II). Additional RFLP screening demonstrated the presence of this subtype in two of three Brazilian blood donors and a Mexican prostitute and her child. In contrast, 129 samples from blood donors and intravenous drug users (IDUs) from the United States, two Pueblo Indian samples, five samples from Norwegian IDUs, and two samples from blood donors from Denmark were all found to be a different HTLV-IIa subtype (A-III). Phylogenetic analysis of two Kayapo and one Mexican LTR sequences showed that they cluster with a subtype A-II sequence from a Brazilian blood donor and with sequences from two prostitutes from Ghana and Cameroon. These results demonstrate that infection with the A-II subtype is endemic among the Kayapo Amerindians, has disseminated to non-Indian populations in Brazil, and is also present in Mexico. Furthermore, the A-II subtype does not appear to represent an origin for the HTLV-IIa infection in urban areas of the United States and Europe. This study provides evidence that HTLV-IIa may be a Paleo-Indian subtype as previously suggested for HTLV-IIb.

Identification and characterization of a new and distinct molecular subtype of human T-cell lymphotropic virus type 2

Molecular studies have demonstrated the existence of at least two major subtypes of human T-cell lymphotropic virus type 2 (HTLV-2), designated HTLV-2a and HTLV-2b. To further investigate the heterogeneity of this family of viruses, we have characterized the HTLV-2 subtypes present in several urban areas in Brazil. DNAs from peripheral blood mononuclear cells of a large number of infected individuals, the majority of whom were intravenous drug abusers, were analyzed by using PCR with restriction fragment length polymorphism and nucleotide sequencing analysis. Restriction fragment length polymorphism analysis of the env region suggested that all individuals were infected with the HTLV-2a subtype, and this was confirmed by nucleotide sequence analysis. In contrast, nucleotide sequence analysis of the long terminal repeat demonstrated that although the viruses were more related to the HTLV-2a than to the HTLV-2b subtype, they clustered in a distinct phylogenetic group, suggesting that they may represent a new and distinct molecular subtype of HTLV-2. This conclusion was supported by nucleotide sequence analysis of the pX region, which demonstrated that the Tax proteins of the Brazilian viruses differed from that of prototype HTLV-2a isolates but were more similar to that of HTLV-2b in that they would be expected to have an additional 25 amino acids at the carboxy terminus. In transient expression assays, the extended Tax protein of the prototype HTLV-2a subtype. The studies suggest that the Brazilian viruses analyzed in this study, while being phylogenetically related to the prototypic HTLV-2a seen in North America, are phenotypically more related to HTLV-2b and can be justifiably classified as a new molecular subtype, which has been tentatively designated HTLV-2c.

Human T lymphotropic virus type II (HTLV-II): epidemiology, molecular properties, and clinical features of infection

Human T lymphotropic virus, type II (HTLV-II), infection has been shown to be endemic in a number of American Indian populations, and high rates of infection have also been documented in intravenous drug abusers in urban areas throughout the world. Although the role of HTLV-II in human disease has yet to be clearly defined, there is accumulating evidence that like HTLV-I, infection may also be associated with rare lymphoproliferative and neurological disorders. In this article we review and summarize the epidemiology, molecular properties and clinical features of HTLV-II infection.

Evidence in Gabon for an intrafamilial clustering with mother-to-child and sexual transmission of a new molecular variant of human T-lymphotropic virus type-II subtype B

Following the observation of an HTLV-II seropositive 60-year-old woman living in Gabon (Central Africa), a serologic and molecular study of her family members was conducted in an attempt to determine the duration of the HTLV-II infection and the modes of transmission of the virus. Among 41 family members, five were HTLV-I seropositive and 7 exhibited specific HTLV-II antibodies in their sera as demonstrated by high immunofluorescence titers on C19 cells and/or specific Western-blot pattern. The second husband of the index case and two of his sisters were infected by the virus, suggesting the presence of HTLV-II in this family over two generations. Sequence analysis of an amplified fragment of 172 nucleotides within the gp21 of the env region (6469-6640) of four HTLV-II infected individuals revealed a new HTLV-II molecular variant of the subtype b diverging from the prototypes NRA and G12 by seven (4.1%) and five (2.9%) bases substitutions, respectively. Molecular analysis of the total env gene (1462 bp) and fragments of the pol and pX regions confirmed that this new African variant was the most divergent HTLV-II subtype b yet described, exhibiting 2.3% of nucleotide substitutions in the env gene (33 bases) as compared to the two HTLV-II b prototypes. These data demonstrate, for the first time in Africa, intrafamilial both mother-to-child transmission and sexual transmission between spouses of an HTLV-II b molecular variant, and also suggest that this virus has been present in Gabon for a long period of time.

The phylogeny and molecular epidemiology of human T-cell lymphotropic virus type II

Phylogenetic analysis of long terminal repeat (LTR) sequences from 29 human T-cell lymphotropic virus type II (HTLV-II) strains from endemic and nonendemic populations led to the proposition of three HTLV-IIa phylogroups (A-I, A-II, and A-III) and four HTLV-IIb phylogroups (B-I, B-II, B-III, B-IV). B-I and B-II represented sequences from U.S. and European intravenous drug users, and B-IV included Amerindian sequences from the Guaymi and Wayuu. Interestingly, sequences from an African Pygmy and Seminole and Pueblo Indians and other non-India U.S. samples clustered together in B-III. Similarly, sequences from the Kayapo Indians from Brazil, a Brazilian blood donor, a Cameroonian, and a Ghanaian prostitute clustered together in A-II. Sequences from non-Indian U.S./European samples and a Pueblo Indian formed A-III. A restriction fragment length polymorphism (RFLP) assay was developed to identify rapidly the prevalence of the A and B phylogroups in 246 HTLV-II samples. The RFLP results suggest that A-III and B-II may represent cosmopolitan subtypes because of global distribution in urban areas. In contrast, B-IV and A-II infections were restricted primarily to Central and South America. The phylogenetic data suggest a possible Amerindian origin for B-III, A-II, and A-III infections in non-Indians and an evolution into A and B subtypes that preceded population migrations to the Americas.

Questions on the evolution of primate T-lymphotropic viruses raised by molecular and epidemiological studies of divergent strains

In human and simian T-lymphotropic viruses (HTLV and STLV), collectively referred to as primate T-lymphotropic viruses (PTLV), four distinct clades can be distinguished: PTLV-I, PTLV-II, and the newly discovered divergent STLVs isolated from hamadryas baboons and from bonobos (pygmy chimpanzees). The hamadryas STLV is clearly distinct from types I and II, in terms both of sequence divergence and of genomic structure, and would qualify as a separate type, provisionally called PTLV-L. The bonobo STLV is closer to, although clearly distinct from, PTLV-II, at present known only in humans. While PTLV-II, PTLV-L, and the bonobo STLV appear presently to be species specific, PTLV-I has spread during its evolution through repeated interspecies transmissions between primates and is now present in many species of Old World monkeys and apes and in humans. The human subtypes of PTLV-I arose from at least three acquisitions from separate simian reservoirs.

What is the situation of human T cell lymphotropic virus type II (HTLV-II) in Africa? Origin and dissemination of genomic subtypes

Human T cell lymphotropic virus type II (HTLV-II) and its two genomic subtypes, A and B, which differ by 3 to 6% at the nucleotide level (depending on the gene studied), were until recently considered to be endemic only in certain Indian tribes in the Americas and were therefore considered mainly as a "New World virus." First, the evidence of HTLV-II antibodies and later characterization of isolates from sex workers or individuals living in large West and Central African cities suggested that HTLV-II subtype A could have been imported recently in Africa. However, the findings of HTLV-II infection in two Pygmy populations living in remote areas of Zaire and Cameroon suggest that HTLV-II might have been in Africa for a very long time. Furthermore, the discovery of HTLV-II subtype B virus in some of these Pygmies, but also in other individuals from Zaire and within a family in Gabon for three generations, confirms the hypothesis of a very ancient presence of this HTLV-II subtype B on the African continent Recent data indicate also that there exist in Central Africa specific HTLV-II divergent strains including an HTLV-II B variant strain in Gabon. In the context of recent evidence for interspecies transmission in Central and West Africa of HTLV-I/simian T cell lymphotropic virus type I (STLV-I) strains, leading to the two major HTLV-I African subtypes, we would like to suggest that some STLV-II (closely related to HTLV-II subtype B) still exist or might have existed in Central/East Africa. The recent finding of quite divergent primate T cell lymphotropic viruses (PTLVs) in several Pygmy chimpanzees of Zairian origin (PTLV-PP1664 and STLV-PP) and in wild-caught baboons in Eritrea, Ethiopia (PTLV-L), also supports the complementary hypothesis of a yet to be discovered new HTLV-II-related virus in humans. Careful study of the indeterminate Western blot patterns present in some populations in Central Africa strongly suggests that such an exciting possibility exists, thus opening new avenues of research on both the history of primate retroviruses and that of early human groups.

A new HTLV type II subtype A isolate in an HIV type 1-infected prostitute from Cameroon, Central Africa

Among 332 female sex workers in Douala, Cameroon, 113 were HIV-1 seropositive, 3 were HTLV-I seropositive, and only 1 had specific anti-HTLV-II antibodies. By cocultivation with BJAB cells, an HTLV-II was isolated from the peripheral blood mononuclear cells of this 32-year-old woman coinfected by HIV-1. This new African HTLV-II isolate (PH230PCAM) belongs to the molecular subtype A, exhibiting, however, a nucleotide variability of 2.4% and 0.8%, vis-à-vis the MO prototype, in the LTR and in the gp21 env gene, respectively. These data, as well as the previous findings of another HTLV-II subtype A in a Ghanean prostitute, suggest that this viral subtype had been imported into Africa, while the HTLV-II subtype B, described in remote areas of Zaire, Gabon, and Cameroon, could be a genuine African HTLV-II, present in this continent for a long period of time.

Identification of human T cell lymphotropic virus type IIa infection in the Kayapo, an indigenous population of Brazil

Human T cell lymphotropic virus type II (HTLV-II) infection is endemic in a number of indigenous populations in North, Central, and South America. In the present study we have employed serological and molecular methods to identify HTLV-II infection in Indian communities in the Amazon region of Brazil. Sera (1324) from 25 different Indian communities were analyzed by ELISA and Western blot. One hundred and four samples (7.8%) from a number of culturally distinct and geographically unrelated populations were found to have reactivities consistent with HTLV-II infection. Of these, 67 were from the Kayapo Indian communities, which had an overall seroprevalence rate of greater than 30%. In addition, high seroprevalence rates were observed in three other communities, the Munduruku, Arara do Laranjal and the Tyrio, suggesting that there are additional foci of endemic infection in the Amazon region. In the Kayapo, seroprevalence rates tended to increase with age, supporting the importance of sexual transmission of the virus, and family studies demonstrated that vertical transmission is also an important route of infection. Restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis of a region of the env gene demonstrated that the Kayapo are infected with the HTLV-IIa subtype. Moreover, nucleotide sequence analysis of the LTR demonstrated that this belonged to a distinct HTLV-IIa phylogenetic group. The identification of HTLV-IIa in the Kayapo is, as far as we are aware, the first identified endemic focus of infection by this subtype of HTLV-II in the Americas.

Molecular analysis of human T-cell lymphotropic virus type II from Wayuu Indians of Colombia demonstrates two subtypes of HTLV-IIb

Studies of the genetic heterogeneity of human T-cell lymphotropic virus type II (HTLV-II) have revealed the presence of two genetic subtypes, termed HTLV-IIa and HTLV-IIb. The HTLV-IIb subtype encodes an immunodominant epitope present at the C-terminus of the extended Tax protein and, by using an LTR-based, restriction fragment-length polymorphism (RFLP) assay, can be further classified into IIb60-IIb5, with HTLV-IIb1 (Central Amerindian-like) and HTLV-IIb5 (North Amerindian-like) being characteristic subtypes for Native American Indians. To determine the antigenic and genetic heterogeneity among HTLV-II-infected South Amerindians, we used a Tax synthetic peptide immunoassay on serum, and RFLP and phylogenetic analysis on LTR sequences amplified from genomic DNA from four Wayuu Indians of Colombia. The Wayuu specimens displayed seroreactivity to the immunodominant epitope located in the extended Tax region, as predicted, and demonstrated genetic heterogeneity by the presence of both the IIB1 (Wyu1, Zuc31) and IIb5 (Wyu2, Zuc42) subtypes sequences within separate phylogroups represented by the Guaymi Indian (IIb1) and North Amerindian (IIb5) sequences, respectively. Sequence analysis showed that major LTR regulatory motifs and the cis-acting repressive elements in the LTR RNA secondary structure were relatively conserved in both Wayuu subtypes, but the predicted secondary structure of the rex response stem loop in the Wyu2 (IIb5) LTR sequence was 45 nucleotides (nt) and 95 nt longer than that observed in the Wyu1 (IIb1) and G12.1 (IIb1) LTR sequences, respectively. These results extend our knowledge of the genetic heterogeneity of HTLV-II in South Amerindians.

Nucleotide sequence and restriction fragment length polymorphism analysis of the long terminal repeat of human T cell leukemia virus type II

Molecular studies have demonstrated the existence of two major subtypes of human T cell leukemia virus type II: HTLV-IIa and HTLV-IIb. In attempts to further classify this family of viruses we have carried out nucleotide sequence and restriction fragment length polymorphism (RFLP) analysis of the long terminal repeat (LTR), a region that has been shown in previous studies to have the greatest intra- and intersubtype genomic divergence. Analysis of the nucleotide sequences suggested the existence of distinct phylogenetic groups in each subtype and, on the basis of predicted differences in restriction endonuclease sites, RFLP analysis allowed the identification of four groups within the IIa subtype (a1-a4) and six within the IIb subtype (b1-b6). Nucleotide sequence analysis also suggested the possible existence of HTLV-II quasispecies. However, this appeared not to be significant, and preliminary studies suggest that these would not be expected to influence the results of RFLP analysis appreciably. The validity of the RFLP method was demonstrated in an analysis of 36 randomly chosen samples from HTLV-II seropositive blood donors from the New York City Blood Center, where it could be shown that all could be successfully classified. Moreover, the RFLP analysis correctly matched the viruses in donors and recipients of contaminated blood in four situations in which HTLV-II was inadvertently transmitted by transfusion. RFLP analysis of the LTR appears to be a rapid and reliable method by which to identify HTLV-II infection. This should prove useful in studies of the epidemiology and the characterization of viruses present both in nonindigenous and indigenous populations.

Extraordinary high rate of HTLV type II seropositivity in intravenous drug abusers in south Vietnam

Serum specimens (n = 1899) were assayed for infections with HTLV-I, HTLV-II, and HIV-1 in seven classified groups of normal healthy controls, children, pregnant women, prostitutes, intravenous drug abusers, patients under going hemodialysis, and hemophiliacs in South and North Vietnam. Surprisingly, 125 of 954 samples from South Vietnam exhibited seropositivity for HTLV-II and 119 of these belonged to the group of IVDAs (n = 200). The remaining six positives were a healthy control, a prostitute, two children, and two patients under going hemodialysis. Two IVDAs who were seropositive for HTLV-I and 10 of 15 seropositives for HIV-1 were also positive for HTLV-II in this population. In contrast, no seropositives to any of the viruses were detected in the North Vietnamese samples (0 of 945). The HTLV-II-seropositive IVDAs exhibited increased seropositivity with age compared with HIV-1 seropositivity in the population, and there was no statistical relation between seropositivity for HTLV-II and HIV-1. The HTLV-IIs in South Vietnam IVDAs appeared, by subtype-specific peptide ELISA, to be a mixture of both subtypes a and b, with subtype a predominant. It seems possible that HTLV-II may have been introduced into this population from IVDAs from the United States during the Vietnam conflict, but in a period prior to, or early in, the introduction of HIV-1 to IVDAs.

Isolation and molecular characterization of a human T-cell lymphotropic virus type II (HTLV-II), subtype B, from a healthy Pygmy living in a remote area of Cameroon: an ancient origin for HTLV-II in Africa

We report characterization of a human T-cell lymphotropic virus type II (HTLV-II) isolated from an interleukin 2-dependent CD8 T-cell line derived from peripheral blood mononuclear cells of a healthy, HTLV-II-seropositive female Bakola Pygmy, aged 59, living in a remote equatorial forest area in south Cameroon. This HTLLV-II isolate, designated PYGCAM-1, reacted in an indirect immunofluorescence assay with HTLV-II and HTLV-I polyclonal antibodies and with an HTLV-I/II gp46 monoclonal antibody but not with HTLV-I gag p19 or p24 monoclonal antibodies. The cell line produced HTLV-I/II p24 core antigen and retroviral particles. The entire env gene (1462 bp) and most of the long terminal repeat (715 bp) of the PYGCAM-1 provirus were amplified by the polymerase chain reaction using HTLV-II-specific primers. Comparison with the long terminal repeat and envelope sequences of prototype HTLV-II strains indicated that PYGCAM-1 belongs to the subtype B group, as it has only 0.5-2% nucleotide divergence from HTLV-II B strains. The finding of antibodies to HTLV-II in sera taken from the father of the woman in 1984 and from three unrelated members of the same population strongly suggests that PYGCAM-1 is a genuine HTLV-II that has been present in this isolated population for a long time. The low genetic divergence of this African isolate from American isolates raises questions about the genetic variability over time and the origin and dissemination of HTLV-II, hitherto considered to be predominantly a New World virus.

Phylogenetic relationship and geographic distribution of multiple human T-cell lymphotropic virus type II subtypes

The current env-based subtyping of human T-cell lymphotropic virus type II (HTLV-II) identifies only two heterogenetic groups, HTLV-IIa and HTLV-IIb. To better understand the genetic diversity and phylogeny of HTLV-II, we examined the most divergent genomic region of HTLV-II, the long terminal repeat, by using restriction fragment length polymorphism (RFLP) and sequence analysis. Long terminal repeat sequences were amplified from peripheral blood mononuclear cells by PCR and digested with seven restriction endonucleases that differentiated HTLV-II into five HTLV-IIa (IIa0 to IIa4) and six HTLV-IIb (IIb0 to IIb5) restriction types, with HTLV-IIa0 and HTLV-IIb0 being prototypes for the MoT and NRA isolates, respectively. We examined 169 HTLV-II-infected samples, including 123 from blood donors and intravenous drug users (IDU) from the Americas, 16 from IDU from Europe, and 30 from Amerindians. Of the 169 samples, 109 (64.5%) were categorized as HTLV-IIa and 60 (35.5%) were categorized as HTLV-IIb. The predominant restriction types seen among the U.S. blood donors and U.S. IDU were IIa0 (68.7%) and IIb4 (10.4%). Four Spanish and seven Italian samples were IIb4, while five Norwegian samples were IIa2. Twelve Guaymi and all ten Seminole samples were single restriction types (IIb1 and IIb5, respectively), whereas the two Navajo and six Pueblo samples had a mixture of restriction types IIa0, IIa4, and IIb5. Of the HTLV-IIb restriction types observed in the U.S. non-Indians, 42.8% appear to have originated from the North Amerindian (IIb5), while 57.2% were similar to the European IIb4 restriction type. Sequences of 15 selected HTLV-II samples were determined and phylogenetically compared with 7 previously published HTLV-II LTR sequences. The derived topologies revealed three HTLV-IIa phylogroups (A-I to A-III) and four HTLV-IIb phylogroups (B-I to B-IV). Furthermore, the HTLV-IIa phylogroups appear to have evolved from the HTLV-IIb phylogroups. In the HTLV-IIa cluster, a Navajo (A-I) and a Brazilian (A-II) sequence formed separate phylogroups, while the remaining IIa sequences formed a single phylogroup (A-III). The four HTLV-IIb phylogroups were represented predominantly by a New York IDU (B-I), European IDU (B-II), North Amerindian and NRA (B-III), and Central Guaymi Indian (B-IV) sequence(s). Comparison of the phylogenetic data with the RFLP results revealed that results of the two methods correlated completely, demonstrating the ability of the RFLP method to predict the phylogroup of HTLV-II-infected samples accurately and quickly. GENBANK/U10258

HTLV infections among Swedish intravenous drug users in 1992

Serum samples collected in 1992 from 1158 intravenous drug users (IVDUs) in Stockholm, Sweden, were tested retrospectively for antibodies to human T-lymphotropic virus type I and II (HTLV-I and II). The overall prevalence rate of HTLV infections was 2.4% (28/1158). A majority of the HTLV infections were caused by HTLV-II (27/28). A significant association between HTLV-II and HIV-1 seropositivity was found, the prevalence of HTLV-II infection being 11.4% (11/96) in HIV-seropositive individuals compared with 1.5% (16/1062) in HIV-seronegative persons (p < 0.001). All the HTLV-infected individuals were of Scandinavian origin. No significant differences in age and sex distribution were observed in HTLV-infected persons compared to seronegative individuals. This study confirms that HTLV-II infection is present in the Swedish IVDU population and the findings provide baseline information for future epidemiological studies.

Detection of HTLV-II-seropositive blood donors in South Vietnam but not in North Vietnam

Approximately 1% (4/500) of blood donors exhibited seropositivity for HTLV-II in South Vietnam, but none (0/500) did in North Vietnam. Further, all individuals seropositive for HTLV-II were intravenous drug abusers who were seronegative for HIV-1 and HTLV-I. These findings suggest that HTLV-II infection may be specifically prevalent in drug abusers in South Vietnam.