HTLV: a stigmatizing infection? / HTLV: uma infecção estigmatizante?

HTLV is a virus that affects human T-cells. Brazil is the country of the world with the largest absolute number of HTLV cases. Estimates by the Ministry of Health point to 700,000 to 2 million infected Brazilians. The majority are asymptomatic carriers, but some persons may develop degenerative neurological conditions such as tropical spastic paraparesis, in addition to leukemia and lymphoma. The forms of transmission and clinical manifestations such as progressive motor incapacity, genitourinary disorders, in addition to restriction of maternal breastfeeding, impact daily life and can lead to social discrimination and stigma. The stigma denotes violation of social norms and reinforces prejudice and inequalities. This article aims to discuss the concept of stigma and its repercussions on persons living with HTLV. The discussion is based on a literature review on the theme and the authors' experience with care for persons affected by the infection and illness. The study found that both HTLV carrier status and HTLV-related illness can be stigmatizing for individuals, who feel inferior for being infected with a potentially serious and even fatal disease, although incompletely understood and loaded with derogatory stereotypes. This situation can have negative repercussions on access to health services, treatment adherence, and pursuit of rights. Public policies should help mitigate such stigmatization, ensuring the rights of individuals in a situation of vulnerability due to HTLV in order from them to live as protagonists in the exercise of their civil rights.

O HTLV é um vírus que afeta as células T humanas. O Brasil é o país com o maior número absoluto de casos de HTLV no mundo. Estimativas do Ministério da Saúde apontam entre 700 mil e 2 milhões de pessoas infectadas. A maioria são portadores assintomáticos, porém algumas pessoas podem vir a desenvolver quadros neurológicos degenerativos como a paraparesia espástica tropical, além de leucemia e linfoma. As formas de transmissão e manifestações clínicas como incapacidade motora progressiva, distúrbios geniturinários, além da restrição ao aleitamento materno impactam o cotidiano e podem ser geradores de discriminação social e estigma. O estigma denota violação das normas sociais e reforça o preconceito e as desigualdades. O objetivo deste artigo é discutir o conceito de estigma e sua repercussão em pessoas que convivem com o HTLV. Trata-se de uma reflexão baseada na revisão da literatura sobre o tema e na vivência do atendimento a pessoas afetadas pela infecção e adoecimento. Constatou-se que ser portador do vírus ou adoecer em decorrência da infecção pelo HTLV pode ser estigmatizante para indivíduos que se sentem inferiorizados ao serem acometidos por uma doença potencialmente grave e até mesmo fatal, ainda pouco conhecida e carregada de estereótipos depreciativos. Essa situação pode repercutir negativamente no acesso aos serviços de saúde, na adesão ao tratamento e na busca por direitos. As políticas públicas devem contribuir para mitigar a estigmatização, assegurando o direito de indivíduos em situação de vulnerabilidade pelo HTLV viverem como protagonistas no exercício de sua cidadania.

El HTLV es un virus que afecta a las células T humanas. Brasil es el país con el mayor número absoluto de casos de HTLV en el mundo. Las estimaciones del Ministerio de Salud indican que existen entre 700 mil y 2 millones de personas infectadas. La mayoría son portadores asintomáticos, sin embargo, algunas personas pueden llegar a desarrollar cuadros neurológicos degenerativos como la paraparesia espástica tropical, además de leucemia y linfoma. Las formas de transmisión y manifestaciones clínicas como incapacidad motora progresiva, disturbios genitourinarios, además de la restricción en la lactancia materna, tienen un impacto en las personas afectadas y pueden causar discriminación social y estigma. El estigma denota una violación de las normas sociales y refuerza el prejuicio y las desigualdades. El objetivo de este artículo es discutir el concepto de estigma y su repercusión en personas que conviven con el HTLV. Se trata de una reflexión basada en la revisión de la literatura sobre el tema y en la vivencia de la atención a personas afectadas por la infección y enfermedad. Se constató que ser portador del virus o enfermar, a consecuencia de la infección por el HTLV, puede ser estigmatizante para individuos que se sienten subestimados al ser atacados por una enfermedad potencialmente grave e incluso fatal, todavía poco conocida y cargada de estereotipos despreciativos. Esta situación puede repercutir negativamente en el acceso a los servicios de salud, en la adhesión al tratamiento y en la búsqueda de derechos. Las políticas públicas deben contribuir a mitigar la estigmatización, asegurando el derecho de los individuos en situación de vulnerabilidad por el HTLV para que vivan como protagonistas en el ejercicio de su ciudadanía.

HTLV: uma infecção estigmatizante? / HTLV: ¿una infección estigmatizante? / HTLV: a stigmatizing infection?

Resumo: O HTLV é um vírus que afeta as células T humanas. O Brasil é o país com o maior número absoluto de casos de HTLV no mundo. Estimativas do Ministério da Saúde apontam entre 700 mil e 2 milhões de pessoas infectadas. A maioria são portadores assintomáticos, porém algumas pessoas podem vir a desenvolver quadros neurológicos degenerativos como a paraparesia espástica tropical, além de leucemia e linfoma. As formas de transmissão e manifestações clínicas como incapacidade motora progressiva, distúrbios geniturinários, além da restrição ao aleitamento materno impactam o cotidiano e podem ser geradores de discriminação social e estigma. O estigma denota violação das normas sociais e reforça o preconceito e as desigualdades. O objetivo deste artigo é discutir o conceito de estigma e sua repercussão em pessoas que convivem com o HTLV. Trata-se de uma reflexão baseada na revisão da literatura sobre o tema e na vivência do atendimento a pessoas afetadas pela infecção e adoecimento. Constatou-se que ser portador do vírus ou adoecer em decorrência da infecção pelo HTLV pode ser estigmatizante para indivíduos que se sentem inferiorizados ao serem acometidos por uma doença potencialmente grave e até mesmo fatal, ainda pouco conhecida e carregada de estereótipos depreciativos. Essa situação pode repercutir negativamente no acesso aos serviços de saúde, na adesão ao tratamento e na busca por direitos. As políticas públicas devem contribuir para mitigar a estigmatização, assegurando o direito de indivíduos em situação de vulnerabilidade pelo HTLV viverem como protagonistas no exercício de sua cidadania.

Resumen: El HTLV es un virus que afecta a las células T humanas. Brasil es el país con el mayor número absoluto de casos de HTLV en el mundo. Las estimaciones del Ministerio de Salud indican que existen entre 700 mil y 2 millones de personas infectadas. La mayoría son portadores asintomáticos, sin embargo, algunas personas pueden llegar a desarrollar cuadros neurológicos degenerativos como la paraparesia espástica tropical, además de leucemia y linfoma. Las formas de transmisión y manifestaciones clínicas como incapacidad motora progresiva, disturbios genitourinarios, además de la restricción en la lactancia materna, tienen un impacto en las personas afectadas y pueden causar discriminación social y estigma. El estigma denota una violación de las normas sociales y refuerza el prejuicio y las desigualdades. El objetivo de este artículo es discutir el concepto de estigma y su repercusión en personas que conviven con el HTLV. Se trata de una reflexión basada en la revisión de la literatura sobre el tema y en la vivencia de la atención a personas afectadas por la infección y enfermedad. Se constató que ser portador del virus o enfermar, a consecuencia de la infección por el HTLV, puede ser estigmatizante para individuos que se sienten subestimados al ser atacados por una enfermedad potencialmente grave e incluso fatal, todavía poco conocida y cargada de estereotipos despreciativos. Esta situación puede repercutir negativamente en el acceso a los servicios de salud, en la adhesión al tratamiento y en la búsqueda de derechos. Las políticas públicas deben contribuir a mitigar la estigmatización, asegurando el derecho de los individuos en situación de vulnerabilidad por el HTLV para que vivan como protagonistas en el ejercicio de su ciudadanía.

Abstract: HTLV is a virus that affects human T-cells. Brazil is the country of the world with the largest absolute number of HTLV cases. Estimates by the Ministry of Health point to 700,000 to 2 million infected Brazilians. The majority are asymptomatic carriers, but some persons may develop degenerative neurological conditions such as tropical spastic paraparesis, in addition to leukemia and lymphoma. The forms of transmission and clinical manifestations such as progressive motor incapacity, genitourinary disorders, in addition to restriction of maternal breastfeeding, impact daily life and can lead to social discrimination and stigma. The stigma denotes violation of social norms and reinforces prejudice and inequalities. This article aims to discuss the concept of stigma and its repercussions on persons living with HTLV. The discussion is based on a literature review on the theme and the authors' experience with care for persons affected by the infection and illness. The study found that both HTLV carrier status and HTLV-related illness can be stigmatizing for individuals, who feel inferior for being infected with a potentially serious and even fatal disease, although incompletely understood and loaded with derogatory stereotypes. This situation can have negative repercussions on access to health services, treatment adherence, and pursuit of rights. Public policies should help mitigate such stigmatization, ensuring the rights of individuals in a situation of vulnerability due to HTLV in order from them to live as protagonists in the exercise of their civil rights.

Infectious etiologies of myelopathy.

Myelopathy refers to a spinal cord disorder that presents with motor and/or sensory deficits. Infectious agents that cause myelopathy do so by either direct infection of neural structures (e.g., polio), a parainfectious mechanism (with a presumed autoimmune pathogenesis), or as a result of involvement of structures adjoining the spinal cord, which may cause a compressive myelopathy. This review of infectious causes of myelopathy focuses on pathogens that are most relevant to clinicians in North America.

Presentation of human T cell leukemia virus type 1 (HTLV-1) Tax protein by dendritic cells: the underlying mechanism of HTLV-1-associated neuroinflammatory disease.

HTLV-1 is the etiologic agent of a debilitating neurologic disorder, HAM/TSP. This disease features a robust immune response including the oligoclonal expansion of CD8+ CTLs specific for the viral oncoprotein Tax. The key pathogenic process resulting in the proliferation of CTLs and the presentation of Tax peptide remains uncharacterized. We have investigated the role of APCs, particularly DCs, in priming of the anti-Tax CTL response under in vitro and in vivo conditions. We investigated two routes (direct vs. indirect) of Tax presentation using live virus, infected primary CD4+/CD25+ T cells, and the CD4+ T cell line (C8166, a HTLV-1-mutated line that only expresses Tax). Our results indicated that DCs are capable of priming a pronounced Tax-specific CTL response in cell cultures consisting of naïve PBLs as well as in HLA-A*0201 transgenic mice (line HHD II). DCs were able to direct the presentation of Tax successfully through infected T cells, live virus, and cell-free Tax. These observations were comparable with those made with a known stimulant of DC maturation, a combination of CD40L and IFN-gamma. Our studies clearly establish a role for this important immune cell component in HTLV-1 immuno/neuropathogenesis and suggest that modulation of DC functions could be an important tool for therapeutic interventions.

[Prelymphoma as a stage of malignant lymphoma (baboon malignant lymphoma model)].

Ten percent of the monkeys (more then 400 animals) from P. hamadrias herd of Sukhumi monkey colony died of a 20 year-long enzootic of malignant lymphoma associated with STLV-1 retrovirus. Retrospective analysis revealed regular (in more than 80% of cases) development of prelymphoma preceded by malignant process for a considerable time (up to 10 years or more). Prelymphoma occurred as mild hemopoietic inhibition including lymphopoiesis. Clinico-morphological signs of prelymphoma were: hypoplasia, edema and discomplexation in lymph nodes, anemia and inflammatory, i. e. degenerative lesions of the skin and mucous membranes.

The human T-cell leukemia virus type 1 (HTLV-1): new insights into the clinical aspects and molecular pathogenesis of adult T-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-associated myelopathy (TSP/HAM).

Human T-cell leukemia virus type 1 (HTLV-1) was the first human retrovirus to be identified in the early 1980s. The isolation and identification of a related virus, HTLV-2, and the distantly related human immunodeficiency virus (HIV) immediately followed. Of the three retroviruses, two are associated definitively with specific diseases, HIV, with acquired immune deficiency syndrome (AIDS) and HTLV-1, with adult T-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). While an estimated 10-20 million people worldwide are infected with HTLV-I, infection is endemic in the Caribbean, parts of Africa, southwestern Japan, and Italy. Approximately 4% of HTLV-I infected individuals develop ATLL, a disease with a poor prognosis. The clinical manifestations of infection and the current biology of HTLV viruses with emphasis on HTLV-1 are discussed in detail. The implications for improvements in diagnosis, treatment, intervention, and vaccination are included, as well as a discussion of the emergence of HTLV-1 and -2 as copathogens among HIV-1-infected individuals.

Skeletal muscle involvement in human immunodeficiency virus (HIV)-infected patients in the era of highly active antiretroviral therapy (HAART).

Skeletal muscle involvement can occur at all stages of human immunodeficiency virus (HIV) infection, and may represent the first manifestation of the disease. Myopathies in HIV-infected patients are classified as follows: (1) HIV-associated myopathies and related conditions, including HIV polymyositis, inclusion-body myositis, nemaline myopathy, diffuse infiltrative lymphocytosis syndrome (DILS), HIV-wasting syndrome, vasculitic processes, myasthenic syndromes, and chronic fatigue; (2) muscle complications of antiretroviral therapy, including zidovudine and toxic mitochondrial myopathies related to other nucleoside-analogue reverse-transcriptase inhibitors (NRTIs), HIV-associated lipodystrophy syndrome, and immune restoration syndrome related to highly active antiretroviral therapy (HAART); (3) opportunistic infections and tumor infiltrations of skeletal muscle; and (4) rhabdomyolysis. Introduction of HAART has dramatically modified the natural history of HIV disease by controlling viral replication, but, in turn, lengthening of the survival of HIV-infected individuals has been associated with an increasing prevalence of iatrogenic conditions.

Dichotomy of all-trans retinoic acid inducing signals for adult T-cell leukemia.

We previously reported that all-trans retinoic acid (ATRA) inhibits growth in human T-cell leukemia virus type 1 (HTLV-1)-positive T-cell lines and fresh cells from patients with adult T-cell leukemia. However, the mechanism of this inhibition is not clear. In the present study, we observed that NF-kappaB transcriptional activity as well as cell growth decreased significantly in HTLV-1-positive T-cell lines in the presence of ATRA. Furthermore, we observed that ATRA reduced HTLV-1 proviral DNA, HTLV-1 genes (gag, tax, or pol mRNA) using the real-time quantitative polymerase chain reaction. SIL-2R was reduced by ATRA in both protein level (culture supernantant) and mRNA level in HTLV-1-positive T-cell lines. Interestingly, ATRA significantly inhibited RT activity similar to azidothimidine (AZT) in HTLV-1-positive T-cell lines. Moreover, AZT inhibited proviral DNA but not NF-kappaB transcriptional activity, and sIL-2R on HTLV-1; however, ATRA inhibited of NF-kappaB, proviral DNA and sIL-2R on HTLV-1. These results suggested that the decrease in sIL-2R induced by ATRA may be caused by the actions of a NF-kappaB inhibitor acting on the NF-kappaB/sIL-2R signal pathway. These results suggested that ATRA could have two roles, as a NF-kappaB inhibitor and as an RT inhibitor.

Ex vivo survival of peripheral blood mononuclear cells in sheep induced by bovine leukemia virus (BLV) mainly occurs in CD5- B cells that express BLV.

Bovine leukemia virus (BLV) is the etiologic agent of enzootic bovine leukosis (EBL). In a previous report, we found that in a sheep model, only CD5(-) B cells proliferated clonally, while CD5(+) B cells rapidly decreased when the disease progressed to the lymphoma stage. We demonstrate here that, although both CD5(+) and CD5(-) B cells, but not CD4(+) T, CD8(+) T and gammadeltaTCR(+)T cells, are protected from spontaneous ex vivo apoptosis in sheep infected with wild-type and a mutant BLV that encodes a mutant Tax D247G protein with elevated trans-activation activity, only CD5(-) B cells become the main target for ex vivo survival when the disease proceeds to the persistent lymphocytotic stage, which showed an increased expansion of the CD5(-) B cells. In addition, we identified, by four-color flow cytometric analysis, that in CD5(-) B cells, the apoptotic rates of cells that expressed wild-type and mutant BLV were greatly decreased compared with those of BLV-negative cells. There was only a slight reduction in the apoptotic rates in BLV-positive cells from CD5(+) B cells. In addition, supernatants from peripheral blood mononuclear cell (PBMC) cultures from wild-type- and mutant BLV-infected sheep mainly protected CD5(-) B cells from spontaneous apoptosis. Our results suggest that, although BLV can protect both CD5(+) and CD5(-) B cells from ex vivo apoptosis, the mechanisms accounting for the ex vivo survival between these two B-cell subsets differ. Therefore, it appears that the phenotypic changes in cells that express CD5 at the lymphoma stage could result from a difference in susceptibility to apoptosis in CD5(+) and CD5(-) B cells in BLV-infected sheep.

Potential role of HOXD9 in synoviocyte proliferation.

OBJECTIVE: To investigate the role of HOXD9 in the proliferation activity of cultured synoviocytes as well as the mechanisms that regulate HOXD9 transcription. METHODS: Synoviocytes from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were transfected with HOXD9 complementary DNA to establish stable transformants that overexpressed HOXD9. HOXD9 expression was detected by Western blotting with anti-HOXD9 antibody. The growth properties of the transformants were investigated by proliferation and colony formation assays. The expression of basic fibroblast growth factor (bFGF), tumor necrosis factor alpha (TNFalpha), interleukin-1beta, c-Fos, and c-Myc was examined by Western blotting. Transcriptional regulation of HOXD9 was examined by transient cotransfection. RESULTS: HOXD9 protein was highly expressed in RA synoviocytes, but there was no expression in OA synoviocytes. HOXD9 transfection induced stable HOXD9 protein expression in synoviocytes and showed an increased proliferation rate under both normal and serum-starved conditions, as well as an enhanced capacity to proliferate anchorage independently to form colonies in soft agar cultures, compared with control transfectants. Higher levels of bFGF and c-Fos were detected in HOXD9 transformants than in controls. Transient cotransfection assays of NIH3T3 fibroblasts and synoviocytes showed that HOXD9 activated the luciferase reporter construct containing the highly conserved region (HCR), an autoregulatory element of HOXD9 promoter. This activation was significantly increased by bFGF, suppressed by TNFalpha, and unchanged by transforming growth factor beta in synoviocytes. Human T lymphotropic virus type I tax also activated the luciferase reporter construct containing the HCR and had a synergistic effect with HOXD9 on HCR promoter activation. CONCLUSION: Our data suggest that HOXD9 plays a potential role in synovial proliferation. In addition, they suggest that the involvement of HOXD9 in the regulation of cellular growth might be mediated, at least in part, by up-regulation of growth-related factors such as bFGF and c-Fos and/or might result from increased transcription activity by its regulators.

Coinfection of macaques with simian immunodeficiency virus and simian T cell leukemia virus type I: effects on virus burdens and disease progression.

To test the hypothesis that coinfection with human immunodeficiency virus (HIV) and human T cell leukemia/lymphoma virus types I or II (HTLV-I or -II) accelerates progression to AIDS, pig-tailed macaques were inoculated with the simian counterparts, SIV and STLV-I. During 2 years of follow-up of singly and dually infected macaques, no differences in SIV burdens, onset of disease, or survival were detected. However, in the first coinfected macaque that died of AIDS (1 year after infection), >50% of CD4+ and CD8+ lymphocytes expressed CD25. On the basis of the low incidence of HTLV-I- and STLV-I-associated disease during natural infections, this early evidence of neoplastic disease was unexpected. While these results demonstrate that coinfection with SIV and STLV-I has no influence on the development of immunodeficiency disease, they do establish a reliable macaque model of persistent STLV-I infection.

Retroviruses and nervous system disease.

During the past decade retroviruses have been recognized as causes of human neurological disease. A wide clinical spectrum of neurological and neuromuscular diseases have been reported with HIV infections, and studies of these diseases have raised novel and exciting hypotheses of pathogenesis. As yet the full clinical spectrum of diseases associated with HTLV-1 has yet to be defined, and the pathogenesis of the chronic spastic paraparesis remains a mystery. Chronic neurological diseases in animals caused by both oncoviruses and lentiviruses can provide some clues to the pathogenesis of these newly recognized human neurological illnesses.

Comparative biological responses of rabbits infected with human T-lymphotropic virus type I isolates from patients with lymphoproliferative and neurodegenerative disease.

An experimental rabbit model was used to determine host responses to infection by various human T-lymphotropic virus type-I (HTLV-I) strains. Seven groups of 4 to 5 rabbits each were inoculated with lethally-irradiated HTLV-I-infected cell lines derived from patients with adult T-cell leukemia/lymphoma or from patients with HTLV-I-associated myelopathy. Four separate control groups of 2 rabbits each were inoculated with similarly prepared HTLV-I-negative cells derived from rabbits or humans. Anti-viral antibody responses were assessed by immunoblot assay and hematologic parameters were measured using automated cell counters and cytologic staining. The virologic status of challenged rabbits was determined by co-culture and HTLV-I antigen capture assay, as well as by polymerase chain reaction (PCR) amplification of HTLV-I DNA from peripheral blood mononuclear cells (PBMC) or tissues. The HTLV-I inocula could be separated into groups based upon their infectivity to rabbits: highly infectious strains elicited intense serologic responses and were detected frequently in tissues by antigen and PCR assays, while other strains were moderately to poorly infectious, induced weak antibody responses and were infrequently detected by antigen and PCR assays. Overall, PBMC appeared to have the greatest quantity of HTLV-I containing cells, while bone marrow was a poor source of virus. No clinical or hematologic abnormalities were evident during the 24-week course of infection. Taken together, our results suggest there is heterogeneity in the biological response to HTLV-I infection which is, in part, dependent on the infecting strain of virus.

Lymphoproliferative disorders developing after transplantation and their relation to simian T-cell leukemia virus infection.

In this report the role of the HTLV-1-like simian T-cell leukemia virus (STLV) during the development of posttransplantation lymphoproliferative disorders (PTLPD) is described. To prevent rejection of an allogeneic transplant in 12 rhesus monkeys cyclosporin A (CyA), prednisone, and/or lymphocyte-specific monoclonal antibodies were used for immunosuppression. Seven monkeys died during the experiment between 22 and 179 days postoperatively. At autopsy in 4 monkeys PTLPD were found. In each case, STLV provirus was acquired during the experiment, either from the blood transfusions or allograft donors. Seroconversion of anti-STLV titers occurred in 3 monkeys. However, Southern blot analysis showed the presence of STLV provirus at the DNA level in all PTLP tissues. PTLPD morphology and phenotype varied significantly. In conclusion, for the first time the oncogenic potential of STLV is identified in a rhesus monkey transplantation model. Moreover, the importance of screening blood and organ donors for HTLV-1 must be emphasized.

NF-kappa B activity in T cells stably expressing the Tax protein of human T cell lymphotropic virus type I.

The effect of constitutive Tax expression on the interaction of NF-kappa B with its recognition sequence and on NF-kappa B-dependent gene expression was examined in T lymphoid Jurkat cell lines (19D and 9J) stably transformed with a Tax expression vector. Tax expressing T cell lines contained a constitutive level of NF-kappa B binding activity, detectable by mobility shift assay and uv cross-linking using a palindromic NF-kappa B probe homologous to the interferon beta PRDII site. In Jurkat and NC2.10 induction with phorbol esters resulted in the appearance of new DNA binding proteins of 85, 75, and 54 kDa, whereas in Tax expressing cells the 85-kDa protein and a 92-kDa DNA binding protein were constitutively induced. Expression of Tax protein in 19D and 9J resulted in transcription of the endogenous NF-kappa B-dependent granulocyte-macrophage colony stimulating factor gene and increased basal level expression of transfected NF-kappa B-regulated promoters. Nonetheless transcription of both the endogenous and the transfected gene was inducible by PMA treatment. Tax expression in Jurkat T cells may alter the stoichiometry of NF-kappa B DNA binding proteins and thus change the expression of NF-kappa B-regulated promoters.

Persistent infection of baboons and rhesus monkeys with different strains of HIV-2.

HIV-2 infection of eight rhesus macaques and two baboons was studied. Most animals were preselected for HIV-2 inoculation by testing their peripheral blood mononuclear cells (PBMC) for susceptibility to virus isolates from the Ivory Coast. The virus strains used (HIV-2UC2, HIV-2UC3, and HIV-2UC7) were also chosen by in vitro screening in PBMC for high replicating ability and cytopathicity. All the animals seroconverted within 2-4 weeks of infection and remained seropositive throughout the duration of the study. One macaque was sacrificed after 2 years, suffering from diarrhea and weight loss, and one baboon died of non-HIV-related causes. The remaining animals are asymptomatic, with normal CD4/CD8 ratios. Virus has been recovered from most animals, and persistent HIV-2 replication has been noted in three macaques and a baboon. Host range studies in T, B, and monocyte cell lines showed little or no differences between isolates obtained after inoculation and the original virus inoculum. However, isolates from the macaque that showed clinical symptoms were more cytopathic as reflected by plaque formation in MT-4 cells. The HIV-2-infected macaque or baboon could be useful as an animal model for elucidating the mechanisms of HIV pathogenesis and for evaluating potential antiviral therapies and vaccines.