Human T-cell leukemia virus type 1 molecular variants, Vanuatu, Melanesia.Four of 391 Ni-Vanuatu women were infected with variants of human T-cell leukemia virus type 1 (HTLV-1) Melanesian subtype C. These strains had env nucleotide sequences [approximately equal to] 99% similar to each other and diverging from the main molecular subtypes of HTLV-1 by 6% to 9%. These strains were likely introduced during ancient human population movements in Melanesia. ********** Human T-cell leukemia virus type 1 (HTLV-1), a human oncoretrovirus, is the etiologic agent of adult T-cell leukemia and of tropical spastic paraparesis/HTLV-1-associated myelopathy. Molecular epidemiologic studies have shown HTLV-1 proviruses to be remarkably stable genetically. The low levels of genetic drift in this virus have been used as a means for monitoring viral transmission and the movement of ancient human populations (1,2). The few nucleotide substitutions observed in HTLV-1 strains are specific to the geographic origin of the patient and are unrelated to viral pathology (1,2). Four major geographic HTLV-1 subtypes have been described: subtype A, cosmopolitan (1,2); subtype B, central African; subtype C, Melanesian (3-6); and subtype D, present in central Africa, mainly in pygmies. Previous reports have indicated that HTLV-1 is endemic in some remote or ancient populations in Melanesia (3-14). These populations include a small number of tribes from Papua New Guinea (especially the Hagahai people) (5) and some inhabitants of the Solomon Islands (7). Evidence of HTLV-1 infection has also been found in some aboriginal groups from Australia (8). Rare cases of adult T-cell leukemia and tropical spastic paraparesis/HTLV-1-associated myelopathy have also been described in these populations (9). Genetic characterization of the few available Melanesian HTLV-1 strains has indicated that these HTLV-1 strains are the most divergent, constituting molecular subtype C (also called Melanesian subtype [3,4,6,10]) in phylogenetic analyses. The discovery of such divergent variants has increased our understanding of the migration of HTLV-1-infected populations throughout the Pacific region. Furthermore, 1 of the calibration methods frequently used, in phylogenetic analyses, to estimate a time scale for the evolution of HTLV and simian T-cell leukemia virus (STLV) appears to coincide with the first human migrations to Melanesia and Australia 40,000-60,000 years ago (2). We carried out a large serologic and molecular study to determine the prevalence of HTLV-1 and associated diseases in the Vanuatu Archipelago. Vanuatu, formerly known as the New Hebrides, is a Y-shaped archipelago made up of [approximately equal to] 80 islands. It is located in Melanesia, in the South Pacific region, northeast of Australia and south of the Solomon Islands. Vanuatu has a population of [approximately equal to] 200,000 inhabitants, most of whom (95%) are of Melanesian origin and are known as the Ni-Vanuatu. Very few seroepidemiologic studies on HTLV-1 in Vanuatu have been carried out, and these studies examined mostly small populations more than a decade ago and were not based on stringent serologic criteria (11-14). No molecular characterization data are available for HTLV-1 from this area. The main goals of this study were to evaluate the situation concerning HTLV-1 infection in a remote Ni-Vanuatu population by using stringent serologic criteria for Western blotting blotting /blot·ting/ (blot´ing) soaking up with or transferring to absorbent material. and molecular characterization of the viruses. The Study In February 2002, we recruited 391 women during a clinical survey for sexually transmitted diseases in various remote rural communities of western Ambae Island in the Penama Province of the Vanuatu Archipelago. Ambae Island, also known as Aoba, has a population of [approximately equal to] 9,500. The women participating in this survey were offered a complete clinical examination, with Papanicolaou test analysis for all women >25 years of age. For each participant, we obtained plasma and buffy coats from 5 mL of blood obtained by venipuncture. The blood samples were rapidly transferred to Institut Pasteur de Nouvelle-Caledonie, where plasma and buffy coats were isolated, frozen, and stored (at -80[degrees]C) until HTLV screening. Informed consent was obtained from each woman participating in the field survey. This study was approved by the Ministry of Health of the Republic of Vanuatu and was supported by the Vanuatu Family Health Association, a local nongovernmental organization. Samples were taken from 391 women (mean age 36 years, range 16-82 years) with the following stratification by age: 11.2% from women 15-24 years of age, 28.4% from women 25-34 years of age, 31.2% from women 35-44 years of age, 17.4% from women 45-54 years of age, and 11.8% from women [greater than or equal to] 55 years of age. Plasma HTLV-1 antibodies were detected by enzyme-linked immunosorbent assay (ELISA) (HTLV-I+II, Abbott-Murex, Kent, United Kingdom) with Western blot (HTLV-I/II Blot 2.4, Diagnostic Biotechnology, Singapore) used for confirmation. On Western blot, plasma samples were considered HTLV-1-positive if they reacted to the 2 Gag proteins (p19 and p24) and both env-encoded glycoproteins: the HTLV-1--specific recombinant gp46-I peptide (MTA-1) and the specific HTLV-1/HTLV-2 recombinant GD 21 protein. Plasma samples were considered negative when no band were shown and indeterminate when partially reactive (15,16). Forty-nine of the 391 plasma samples studied tested positive or borderline by ELISA, and 4 of these samples displayed full reactivity on Western blot (Figure 1). One sample also displayed a typical HTLV gag-indeterminate profile (16), and 6 displayed weak reactivity (19 or GD 21 bands). The 4 plasma samples testing positive by Western blot had higher immunofluorescence assay titers on MT2 (HTLV-1) cells than on C19 (HTLV-2) cells and high particle agglutination 1. the action of an agglutinant substance. 2. the process of union in wound healing. 3. the clumping together in suspension of antigen-bearing cells, microorganisms, or particles in the presence of specific antibodies (agglutinins). titers (Table 1). We
carried out a second serologic survey on 64 members of the families of
the 4 women seropositive for HTLV-1. This survey identified 2 more
infected women; 1 was the mother of an index patient, and the other was
the sister-in-law of another index patient (Table 1). These results
confirm the circulation of HTLV-1 in this population.[FIGURE 1 OMITTED] High molecular-weight DNA was extracted from buffy coats from the 4 HTLV-1--seropositive women, 5 HTLV-1--seronegative persons, and 6 others with indeterminate Western blot results, by using the QIAamp DNA Blood Mini Kit (Qiagen GmbH, Hilden, Germany). The 15 DNA samples studied were subjected to polymerase chain reaction with primers specific for the human [beta]-globin 1. the protein constituent of hemoglobin. 2. any of a group of proteins similar to the typical globin. glo·bin (gl ![]() b gene to check that cellular DNA was amplifiable for
all samples (17). We then subjected DNA samples to 2 series of
polymerase chain reaction to obtain the complete long terminal repeat
(LTR) (755 bp) and a 522-bp region of the env gene as previously
described (18). Fragments of the appropriate size were amplified for the
4 HTLV-1--seropositive women, whereas the other 11 samples yielded
negative results. The amplified products were cloned and sequenced, and
phylogenetic studies were performed as previously described (18). Both
the complete LTR and the 522-bp env fragment were obtained for the 4
HTLV-1--seropositive women.Conclusions The gp21 gene sequences of the 4 HTLV-1 strains involved were almost identical (99.6%-99.8 % nucleotide similarity) and were very similar to those of Melanesian strains. These strains were closely related (99.4%) to certain strains from Solomon Islanders (Mel 4, 8) but were only 97.1%-98.3% similar to strains from Papua New Guinea residents (Mel 2, 7) and from Australian aborigines Australian aborigines, native people of Australia who probably came from somewhere in Asia more than 40,000 years ago. In 2001 the population of aborigines and Torres Straits Islanders was 366,429, 1.9% of the Australian population as a whole and slightly more than the estimated aboriginal population of 350,000 at the time of European colonization in the late 18th cent. (MSHR-1), respectively. Finally, the sequences of these new strains diverged from those of HTLV-1 strains from the 3 other main molecular subtypes (A, B, D) by 6% to 9%. The 4 new HTLV-1 LTR sequences were also very closely related (98%-100% nucleotide similarity). They displayed 2% nucleotide divergence from Mel 5 (from a Solomon Islander), the only available LTR from all the HTLV-1 subtype C strains. However, they also displayed up to 11% nucleotide divergence from HTLV-1 strains from other molecular subtypes. Phylogenetic analyses were performed on all the available env and LTR HTLV-1 sequences from Melanesia, and on several representatives of HTLV-1 and STLV-1 strains from the various subtypes/subgroups as described (18), by the neighbor-joining (NJ) method. Similar tree topologies were obtained for both genomic regions (Figure 2 and Appendix Figure, which is available online at http://www.cdc.gov/ncidod/EID/vol11no05/04-1015_app.htm). Analyses of these trees confirmed that the 4 novel Vanuatu HTLV-1 strains were closely related to all available HTLV-1 subtype C strains (Table 2). Indeed, in the era, analysis, which included 71 HTLV-1 strains (including 12 Melanesian strains and 1 from an Australian aborigine, Table 2) and 55 STLV-1 strains, the 4 new HTLV-1 strains clustered with subtype C (Figure 2). This subtype only includes strains from Australia, Papua New Guinea, the Solomon Islands, and Vanuatu. Within this clade are at least 2 subgroups, strongly supported phylogenetically: 1 comprises the Vanuatu strains and most of the strains from the Solomon Islands (bootstrap values of 88%), and the other comprises the 3 isolates from Papua New Guinea (the Hagahai population), with a bootstrap value of 100%. Two other unique and divergent strains, the only strain available from an Australian aborigine (MSHR-1) and the other from a Solomon Islander (Mel-12), may represent prototypes of 2 other clades CLADES - Centro Latinoamericano de Desarrollo Sustentable (Spanish) within the Melanesian subtype C. [FIGURE 2 OMITTED]ruth In conclusion, we report, for the first time, the presence of HTLV-1 infection in a Ni-Vanuatu population living in remote villages. We also demonstrate that the viruses infecting these Ni-Vanuatu persons are novel HTLV-1 molecular variants belonging to the Melanesian divergent C subtype. This finding suggests that these viruses were introduced into Vanuatu by ancient migrations of Melanesian populations. The first people to reach Santa Cruz, Banks, Vanuatu, and the Loyalties Islands [approximately equal to] 3,600 years ago seem to have been Austronesian Austronesian (ôs'trōnē`zhən, –shən), name sometimes used for the Malayo-Polynesian languages. speakers (19). Epidemiologic and clinical surveys are under way in this area to determine the extent of such retroviral infection and associated neurologic and hematologic diseases. In addition, studies of viral and mitochondrial/nuclear DNA are being conducted and should provide insight into the migrations of the first settlers and the origin, evolution, and modes of dissemination of such retroviruses.
Table 1. Human T-cell leukemia virus type 1 (HTLV-1) antibody titers
and molecular screening results for HTLV-1-seropositive women from
Ambae Island, Vanuatu Archipelago *
IFA titers
Virus strain Age (y) PA titers MT 2 C 19
VAN 54 45 1/2,048 1/320 1/80
VAN 136 36 1/8,192 1/1,280 1/320
VAN 251 42 1/1,024 1/40 <1/20
VAN 335 42 1/4,096 1/1,280 1/160
DH1SIL2 (sister-in-law
of VAN 335) 56 1/8,192 1/2,560 1/320
AWM (mother of VAN 54) 63 1/1,024 1/160 1/40
PCR
Virus strain WB pattern 3' LTR 5' LTR env
VAN 54 HTLV-I + + +
VAN 136 HTLV-I + + +
VAN 251 HTLV-I + + +
VAN 335 HTLV-I + + +
DH1SIL2 (sister-in-law
of VAN 335) HTLV-I NA NA NA
AWM (mother of VAN 54) HTLV-I NA NA NA
* PA, particle agglutination; IFA, immunofluorescence assay; WB,
Western blot; PCR, polymerase chain reaction; LTR, long terminal
repeat; NA, DNA not available.
Table 2. Epidemiologic data and GenBank accession numbers of the
human T-cell leukemia virus type 1 (HTLV-1) strains of the Melanesian
subtype C
Age Clinical
Country of origin (y) Sex Birth Residence status
Vanuatu 45 F Ambae Filakalaka AC
36 F Ambae Ndui Ndui AC
42 F Ambae Vinangwangwe AC
42 F Ambae Lolobinanungwa AC
Papua New Guinea 21 M Madang Madang AC
60 F Madang Madang AC
31 M Madang Madang AC
Solomon Islands 39 F New Georgia Guadalcanal AC
60 F Guadalcanal Guadalcanal AC
58 M Guadalcanal Guadalcanal AC
38 M Guadalcanal Guadalcanal TSP/HAM
49 M New Georgia Guadalcanal AC
75 M Rendova Guadalcanal AC
13 F Guadalcanal Guadalcanal AC
42 F Guadalcanal Guadalcanal AC
60 F Guadalcanal Guadalcanal AC
Australia NA NA NA NA AC
env GenBank LTR GenBank
Country of origin Virus name accession no. accession no.
Vanuatu HTLV-1 VAN 54 AY549879 AY549875
HTLV-1 VAN 136 AY549880 AY549876
HTLV-1 VAN 251 AY549881 AY549877
HTLV-1 VAN 335 AY549882 AY549878
Papua New Guinea HTLV-1 MEL 1 L02533 NA
HTLV-1 MEL 2 M94197 NA
HTLV-1 MEL 7 U11576 NA
Solomon Islands HTLV-1 MEL 3 M94198 NA
HTLV-1 MEL 4 M94199 NA
HTLV-1 MEL 5 M94200 L02534
HTLV-1 MEL 6 M93099 NA
HTLV-1 MEL 8 U11578 NA
HTLV-1 MEL 9 U11580 NA
HTLV-1 MEL 10 U11566 NA
HTLV-1 MEL 11 U11568 NA
HTLV-1 MEL 12 U11570 NA
Australia HTLV-1 MSHR-1 M92818 NA
* LTR, long terminal repeat; F, female; M, male; AC, Asymptomatic
carrier; TSP/HAM, tropical spastic paraparesis/HTLV-1--associated
myelopathy; NA, not available.
Acknowledgments We thank Myriam Abel, Maturine Tary, Rose Bahor, Yvanna Taga, and Rachel Wells for their continual support and interest in this work; Blandine Boulekone, Helene Walter, and Woreka Mera for field work; Sylviane Bassot, Francoise Charavay, and Frederic Touzain for excellent assistance during serologic testing of the samples; and Renaud Mahieux for critically reviewing this manuscript. This study received financial support from the Institut Pasteur, the Institut Pasteur de Nouvelle-Caledonie, and the Regional Office for the Western Pacific of the World Health Organization (WHO-WPRO). Laurent Meertens was supported by a fellowship from the Caisse Nationale d'Assurance Maladie (CANAM) and the Pasteur-Weizmann Foundation. References (1.) Gessain A, Gallo RC, Franchini G. Low degree of human T-cell leukemia/lymphoma virus type I genetic drill in vivo as a means of monitoring viral transmission and movement of ancient human populations. J Virol. 1992;66:2288-95. (2.) Slattery JP, Franchini G, Gessain A. Genomic evolution, patterns of global dissemination, and interspecies transmission of human and simian T-cell leukemia/lymphotropic viruses. Genome Res. 1999;9:525-40. (3.) Gessain A, Boeri E, Yanagihara R, Gallo RC, Franchini G. Complete nucleotide sequence of a highly divergent human T-cell leukemia (lymphotropic) virus type I (HTLV-I) variant from Melanesia: genetic and phylogenetic relationship to HTLV-I strains from other geographical regions. J Virol. 1993;67:1015-23. (4.) Gessain A, Yanagihara R, Franchini G, Garruto RM, Jenkins CL, Ajdukiewicz AB, et al. Highly divergent molecular variants of human T-lymphotropic virus type 1 from isolated populations in Papua New Guinea and the Solomon Islands. Proc Natl Acad Sci U S A. 1991;88:7694-8. (5.) Saksena NK, Sherman MP, Yanagihara R, Dube DK, Poiesz BJ. LTR sequence and phylogenetic analyses of a newly discovered variant of HTLV-1 isolated from the Hagahai of Papua New Guinea. Virology. 1992;189:1-9. (6.) Yanagihara R. Geographic-specific genotypes or topotypes of human T-cell lymphotropic virus type I as markers for early and recent migrations of human populations. Adv Virus Res. 1994;43:147-86. (7.) Yanagihara R, Ajdukiewicz AB, Garruto RM, Sharlow ER, Wu XY, Alemaena O, et al. Human T-lymphotropic virus type 1 infection in the Solomon Islands. Am J Trop Med Hyg. 1991;44:122-30. (8.) Bastian I, Gardner J, Webb D, Gardner I. Isolation of a human T-lymphotropic virus type I strain from Australian aboriginals. J Virol. 1993;67:843-51. (9.) Seaton RA, Wembri JP, Nwokolo NC. Clinical associations with human T-cell lymphotropic virus typed in Papua New Guinea. Med J Aust. 1996;165:403-6. (10.) Nerurkar VR, Song KJ, Bastian IB, Garin B, Franchini G, Yanagihara R. Genotyping of human T cell lymphotropic virus type 1 using Australo-Melanesian topotype-specific oligonucleotide primer-based polymerase chain reaction: insights into viral evolution and dissemination. J Infect Dis. 1994;170:1353-60. (11.) Asher DM, Goudsmit J, Pomeroy KL, Garruto RM, Bakker M, Ono SG, et al. Antibodies to HTLV-1 in populations of the southwestern Pacific. J Med Virol. 1988;26:339-51. (12.) Brindle RJ, Eglin RP, Parsons A J, Hill AV, Selkon JB. HTLV-1, HIV-1, hepatitis B and hepatitis delta in the Pacific and South-East Asia: a serological survey. Epidemiol Infect. 1988; 100:153-6. (13.) Nicholson SR, Efandis T, Dimitrakakis M, Karopoulos A. Lee H, Gust ID. HTLV-I infection in selected populations in Australia and the western Pacific region. Med J Aust. 1992:156:878-80. (14.) Zhao LG, Yanagihara R, Mora C, Garruto RM, Wong TW. Gajdusek D(aniel) Carleton Born 1923. American virologist. He shared a 1976 Nobel Prize for research on the origin and spread of infectious diseases. (15.) Gessain A, Mahieux R, De The G. HTLV-I "indeterminate'" Western blot patterns observed in sera from tropical regions: the situation revisited. J Acquir Immune Defic Syndr Hum Retrovirol. 1995:9:316-9. (16.) Mauclcre P. Le Hesran JY, Mahieux R, Salla R, Mfouponendoun J, Abada ET, et al. Demographic, ethnic, and geographic differences between human T cell lymphotropic virus (HTLV) type I--seropositive carriers and persons with HTLV-I Gag-indeterminate Western blots in Central Africa. J Infect Dis. 1997;176:505-9. (17.) Mahieux R, Horal P, Mauclere P, Mercereau-Puijalon O, Guillotte M, Meertens L, et al. Human T-cell lymphotropic virus type 1 gag indeterminate Western blot patterns in Central Africa: relationship to Plasmodium falciparum infection. J Clin Microbiol. 2000:38:4049-57. (18.) Meertens L, Rigoulet J, Mauclere P, Van Beveren M, Chen GM, Diop O, et al. Molecular and phylogenetic analyses of 16 novel simian T-cell leukemia virus type 1 from Africa: close relationship of STLV-1 from Allenopithecus nigroviridis to HTLV-1 subtype B strains. Virology. 2001:287:275-85. (19.) Cavalli-Sforza LL, Menozzi P, Piazza A. Australia, New Guinea, and the Pacific Islands. In: The history and geography of human genes. Princeton (NJ): Princeton University Press: 1994. p. 343-71. Olivier Cassar,* [dagger] Corinne Capuano, [double dagger] Laurent Meertens, [dagger] Eliane Chungue,* and Antoine Gessain [dagger] * Institut Pasteur de Nouvelle-Caledonie, Noumea, France; [dagger] Institut Pasteur, Paris, France; and [double dagger] World Health Organization, Port-Vila, Vanuatu Address for correspondence: Antoine Gessain, Unite d'Epidemiologie et Physiopathologie des Virus Oncogenes, Departement des Ecosytemes et Epidemiologie des Maladies Infectieuses, Batiment Lwoff, Institut Pasteur, 28 Rue du Dr. Roux, 75724 Paris, Cedex 15, France; fax: 33-1-40-61-34-65; email: agessain@pasteur.fr Mr. Cassar is a PhD student whose primary research interests are the clinical and molecular epidemiology and physiopathology of dengue viruses. He is currently working on the epidemiology of HTLV-1 in Melanesian populations. |
|
||||||||||||||||||||


b
Printer friendly
Cite/link
Email
Feedback
Reader Opinion