Myelopathy among Brazilians coinfected with human T-cell lymphotropic virus type I and HIV

Immunological and Neurological Signatures of the Co-Infection of HIV and HTLV: Current Insights and Future Perspectives

The human retroviruses HIV and HTLV-1/HTLV-2 are transmitted through similar pathways but result in markedly different diseases. This review delineates the immune-mediated mechanisms by which HTLVs influence HIV pathology in co-infected individuals. In the context of HIV co-infection, HTLV-1/HTLV-2 alter the cellular microenvironment to enhance their own survival while simultaneously impeding the progression of HIV. Despite the extensive body of literature on the biological and clinical implications of retroviral co-infections, decades of research have been marred by controversy due to several flawed epidemiological studies and anecdotal reports lacking robust statistical and scientific backing. Nevertheless, recent systematic and well-designed research has led to a growing consensus supporting at least three key conclusions: (1) co-infections of HIV-1 and HTLV-1 are frequently observed in patients with elevated CD4+ T-cell counts who present with lymphoma or neurological complications; (2) HIV-1 and HTLV-2 co-infections have been associated in some instances with a "long-term non-progressor" phenotype; (3) the differential function and/or overexpression of the HTLV-1 and HTLV-2 Tax proteins are likely crucial in the clinical and immunologic outcomes of HIV/HTLV-1 and -2 co-infections. The present review will provide a comprehensive account of research on retroviral co-infections, focusing particularly on their clinical manifestations and associated pathological features.

Socio-Demographic, Clinical, and Mortality Differences between HIV-Infected and HIV/HTLV-1 Co-Infected Patients in Peru

BACKGROUND AND AIMS

In Peru, the estimated prevalence of human immunodeficiency virus (HIV) and human T-lymphotropic virus-1 (HTLV-1) co-infection has been reported to be as high as 18%. Despite the endemicity of HTLV-1 in Peru, few studies have assessed the impact of HIV/HTLV-1 co-infection. Our study compared socio-demographic and clinical characteristics, and mortality rates between HIV-infected and HIV/HTLV-1 co-infected patients.

METHODS

We reviewed the medical records of patients aged 18 years and older belonging to the HIV and HTLV-1 cohorts in Lima during a 30-year period: 1989-2019. Each HIV/HTLV-1 co-infected patient was randomly matched with two HIV-infected patients with similar characteristics (same sex, age ± 5 years, and same year of HIV diagnosis). Allegedly co-infected patients without a confirmatory diagnosis of HIV and HTLV-1 were excluded. Most of the patients in the HIV-infected group did not have a negative test result for HTLV-1 infection, so we used two probabilistic sensitivity analysis models to correct for potential HTLV-1 exposure misclassification bias in the group of HIV-infected patients.

RESULTS

Of 162 patients enrolled, 54 were HIV/HTLV-1 co-infected and 108 were HIV-infected. The median age was 42 years (IQR = 34-51 years) and the majority were male (61.1%), single (44.4%), heterosexual (71%), born in Lima (58%), educated at the secondary school level (55.6%), and receiving antiretroviral treatment (91.4%). HIV/HTLV-1 co-infection was associated with an increased risk of death (HR: 11.8; 95% CI: 1.55-89.00; p = 0.017) while antiretroviral treatment was associated with a decreased risk of death (HR: 0.03; 95% CI: 0.003-0.25; p = 0.001). The overall mortality rate was 13.6 per 100 persons and the survival time for co-infected patients (median = 14.19 years) was significantly shorter than that of HIV-infected patients (median = 23.83 years) (p < 0.001).

CONCLUSIONS

HIV/HTLV-1 co-infected patients had a significantly shorter survival time compared to HIV-infected patients, suggesting that the immune alterations caused by HTLV-1 in CD4 cell count may have contributed to late initiation of antiretroviral treatment and prophylaxis against opportunistic infections over the decades, and thus reducing their benefits in these patients.

HTLV-1 Coinfection among Patients Attending a Large HIV Treatment Centre in Trinidad

Studies have shown that HIV-1/HTLV-1 coinfected patients tend to have higher CD4+ counts than HIV singly infected patients. Two chart reviews were conducted at initial enrolment among patients attending a large HIV Clinic in Trinidad, one to determine the prevalence of HIV-1/HVLV-1 coinfection and another to compare the CD4+ counts and opportunistic infections among HIV-1/HTLV-1 coinfected patients compared to a randomly selected comparison group of HIV-1 singly infected patients. Sociodemographic, clinical and laboratory data were collected and analysed using SPSS Version 25. During the period April 2002−December 2018, 8916 HIV-1 patients were enrolled at the clinic; 159 were HIV-1/HTLV-1 coinfected; the age range was 18−81 years; the median age was 40 years; 87 (54.7%) were females; and the median CD4+ count and median HIV-1 viral load at enrolment were 300 cells/mm3 and 128,543 copies/mL, respectively, with an HTLV-1 seroprevalence of 1.78%. Among the 477 HIV-1 singly infected patients, the age range was 18−71 years; the median age was 33 years; 248 (52.0%) were males; and the median CD4+ count and the median HIV viral load were 295 cells/mm3 and 23,369 copies/mL, respectively. Opportunistic infections (OIs) were diagnosed in 59 (37.1%) of the coinfected patients versus 48 (10.1%) among those HIV singly infected (p < 0.001). HIV-1/HTLV-1 coinfected patients had higher HIV-1 viral loads (p < 0.001) and more OIs, suggesting a worse prognosis though there were no statistically significant differences in CD4+ counts (p = 0.96) as compared to the HIV-1 mono-infected patients.

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

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

Neurological Aspects of HIV-1/HTLV-1 and HIV-1/HTLV-2 Coinfection

Simultaneous infection by human immunodeficiency viruses (HIV) and human T-lymphotropic viruses (HTLV) are not uncommon since they have similar means of transmission and are simultaneously endemic in many populations. Besides causing severe immune dysfunction, these viruses are neuropathogenic and can cause neurological diseases through direct and indirect mechanisms. Many pieces of evidence at present show that coinfection may alter the natural history of general and, more specifically, neurological disorders through different mechanisms. In this review, we summarize the current evidence on the influence of coinfection on the progression and outcome of neurological complications of HTLV-1/2 and HIV-1.

STLV-1 co-infection is correlated with an increased SFV proviral load in the peripheral blood of SFV/STLV-1 naturally infected non-human primates

Simian T-Leukemia Virus type 1 and Simian Foamy Virus infect non-human primates. While STLV-1, as HTLV-1, causes Adult T-cell Leukemia/lymphoma, SFV infection is asymptomatic. Both retroviruses can be transmitted from NHPs to humans through bites that allow contact between infected saliva and recipient blood. Because both viruses infect CD4+ T-cells, they might interfere with each other replication, and this might impact viral transmission. Impact of STLV-1 co-infection on SFV replication was analyzed in 18 SFV-positive/STLV-1-negative and 18 naturally SFV/STLV-1 co-infected Papio anubis. Even if 9 animals were found STLV-1-positive in saliva, STLV-1 PVL was much higher in the blood. SFV proviruses were detected in the saliva of all animals. Interestingly, SFV proviral load was much higher in the blood of STLV-1/SFV co-infected animals, compared to STLV-1-negative animals. Given that soluble Tax protein can enter uninfected cells, we tested its effect on foamy virus promoter and we show that Tax protein can transactivate the foamy LTR. This demonstrates that true STLV-1 co-infection or Tax only has an impact on SFV replication and may influence the ability of the virus to be zoonotically transmitted as well as its ability to promote hematological abnormalities.

Foamy viruses infect a lot of mammalian hosts including non-human primates (NHP) and humans. Foamy infection is not associated with disease, although a recent report described hematological abnormalities in infected humans. Some NHP species are also naturally infected with another retrovirus i.e. Simian T lymphotropic virus type 1, while humans are infected with the Human T lymphotropic virus type 1 counterpart. Both viruses cause leukemia. Here we report that natural foamy/STLV-1 co-infection is associated with a higher foamy virus proviral load in blood. Co-infected animals might therefore present a higher risk of developing hematological disease.

HTLV-1, the Other Pathogenic Yet Neglected Human Retrovirus: From Transmission to Therapeutic Treatment

Going back to their discovery in the early 1980s, both the Human T-cell Leukemia virus type-1 (HTLV-1) and the Human Immunodeficiency Virus type-1 (HIV-1) greatly fascinated the virology scene, not only because they were the first human retroviruses discovered, but also because they were associated with fatal diseases in the human population. In almost four decades of scientific research, both viruses have had different fates, HTLV-1 being often upstaged by HIV-1. However, although being very close in terms of genome organization, cellular tropism, and viral replication, HIV-1 and HTLV-1 are not completely commutable in terms of treatment, especially because of the opposite fate of the cells they infect: death versus immortalization, respectively. Nowadays, the antiretroviral therapies developed to treat HIV-1 infected individuals and to limit HIV-1 spread among the human population have a poor or no effect on HTLV-1 infected individuals, and thus, do not prevent the development of HTLV-1-associated diseases, which still lack highly efficient treatments. The present review mainly focuses on the course of HTLV-1 infection, from the initial infection of the host to diseases development and associated treatments, but also investigates HIV-1/HTLV-1 co-infection events and their impact on diseases development.

A comparative study of human T-cell lymphotropic virus-associated myelopathy in HIV-positive and HIV-negative patients in KwaZulu-Natal

Background

KwaZulu-Natal is an endemic area for HIV and human T-cell lymphotropic virus (HTLV) infection. The main neurological manifestation of HTLV is HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The effect of HIV co-infection in patients with HAM/TSP is not well documented.

Aims

To determine the prevalence of HIV seropositivity in patients with HAM/TSP and compare the clinical, laboratory and radiological features of patients mono-infected with HTLV and those dually infected with HTLV and HIV.

Methods

Adult patients referred to the Neurology Department at Inkosi Albert Luthuli Central Hospital in KwaZulu-Natal, South Africa, for the period 01 January 2004 to 31 December 2015 with a positive HTLV serology were identified from the National Health Laboratory Service database. A retrospective chart review was conducted to identify all patients who had a diagnosis of HAM/TSP and to record their HIV status. Clinical, laboratory and radiological data were compared for HIV-positive and HIV-negative patients.

Results

A total of 52 patients with HAM/TSP were identified. HIV results were available in 44 patients of whom 23 (52%) patients were HIV co-infected. Patients who were HIV-positive had a younger age of presentation compared to HIV-negative patients (median: 31 vs 50 years, p = 0.002). HIV-positive patients had a median duration of symptoms at presentation of 12 months compared to 16 months for HIV-negative patients, but the difference did not reach statistical significance (p = 0.082). The CD4 cell counts of HIV-positive patients were well preserved with a median count of 781 cells/µL.

Conclusions

HIV co-infection is commonly seen in the setting of HAM/TSP in KwaZulu-Natal. An interaction between the viruses may accelerate the development of HAM/TSP, leading to a younger age of presentation. Co-infection may have treatment implications because of CD4 counts being preserved in these patients.

Acute myelitis as presenting symptom of HIV-HTLV-1 co-infection

A 21-year-old woman presented with acute-onset spastic paraparesis. The MRI spinal scan revealed a contrast-enhanced T2 hyperintensity between C5-T2. The most common neurotropic pathogens were excluded by first level tests. Under suspicion of an acute immune-mediated myelitis, a corticosteroid therapy was administered. However, a seropositivity for both human immunodeficiency virus (HIV) type 1 and human T-lymphotropic virus (HTLV) subsequently emerged. An antiretroviral therapy was started while steroids discontinued. Patient's clinical conditions remained unchanged. HIV-HTLV-1 co-infection should be included in the differential diagnosis of any acute myelitis, even in patients with a preserved immune status and no risk factors.

HIV peripheral neuropathy

Peripheral neuropathies are the most common neurological manifestations occurring in HIV-infected individuals. Distal symmetrical sensory neuropathy is the most common form encountered today and is one of the few that are specific to HIV infection or its treatment. The wide variety of other neuropathies is akin to the neuropathies seen in the general population and should be managed accordingly. In the pre-ART era, neuropathies were categorized according to the CD4 count and HIV viral load. In the early stages of HIV infection when CD4 count is high, the inflammatory demyelinating neuropathies predominate and in the late stages with the decline of CD4 count opportunistic infection-related neuropathies prevail. That scenario has changed with the present almost universal use of ART (antiretroviral therapy). Hence, HIV-associated peripheral neuropathies are better classified according to their clinical presentations: distal symmetrical polyneuropathy, acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), mononeuropathies, mononeuropathies multiplex and cranial neuropathies, autonomic neuropathy, lumbosacral polyradiculomyelopathy, and amyotrophic lateral sclerosis (ALS)-like motor neuropathy. Treated with ART, HIV-infected individuals are living longer and are at a higher risk of metabolic and age-related complications; moreover they are also prone to the potentially neurotoxic effects of ART. There are no epidemiological data regarding the incidence and prevalence of the peripheral neuropathies. In the pre-ART era, most data were from case reports, series of patients, and pooled autopsy data. At that time the histopathological evidence of neuropathies in autopsy series was almost 100%. In large prospective cohorts presently being evaluated, it has been found that 57% of HIV-infected individuals have distal symmetrical sensory neuropathy and 38% have neuropathic pain. It is now clear that distal symmetrical sensory neuropathy is caused predominantly by the ART's neurotoxic effect but may also be caused by the HIV itself. With a sizeable morbidity, the neuropathic pain caused by distal symmetrical sensory neuropathy is very difficult to manage; it is often necessary to change the ART regimen before deciding upon the putative role of HIV infection itself. If the change does not improve the pain, there are few options available; the most common drugs used for neuropathic pain are usually not effective. One is left with cannabis, which cannot be recommended as routine therapy, recombinant human nerve growth factor, which is unavailable, and topical capsaicin with its side-effects. Much has been done to and learned from HIV infection in humans; HIV-infected individuals, treated with ART, are now dying mostly from cardiovascular disease and non-AIDS-related cancers. It hence behooves us to find new approaches to mitigate the residual neurological morbidity that still impacts the quality of life of that population.

Antiretroviral therapy promotes an inflammatory-like pattern of human T-cell lymphotropic virus type 1 (HTLV-1) replication in human immunodeficiency virus type 1/HTLV-1 co-infected individuals

Upon antiretroviral therapy (ART) human immunodeficiency virus (HIV)/human T-cell lymphotropic virus type 1 (HTLV-1) co-infected individuals frequently develop neurological disorders through hitherto unknown mechanisms. Here, we show that effective anti-HIV ART increases HTLV-1 proviral load through a polyclonal integration pattern of HTLV-1 in both CD4(+) and CD8(+) T-cell subsets that is reminiscent of that typically associated with HTLV-1-related inflammatory conditions. These data indicate that preventing ART-triggered clonal expansion of HTLV-1-infected cells in co-infected individuals deserves investigation.

Neurological manifestations of coinfection with HIV and human T-lymphotropic virus type 1

HIV-individuals are at risk for human T-lymphotropic virus (HTLV) coinfection and neurological diseases. Little is known about the impact of HAART among coinfected patients. In this study, 47 out of 428 HIV individuals were coinfected with HTLV (10.9%). Coinfection was an independent variable associated with neurological outcome (odds ratio 8.73). Coinfection was associated with myelopathy [chi square (X(2)) = 93, P < 0.001], peripheral neuropathy (X(2) = 6.5, P = 0.01), and hepatitis C virus infection (X(2) = 36.5, P < 0.001). HAART did not appear to protect against neurological diseases and had no impact on HTLV proviral load.

HTLV-1 and neurological conditions: when to suspect and when to order a diagnostic test for HTLV-1 infection?

HTLV-1 is a retrovirus associated with a myriad of clinical conditions, especially hematological and neurological ones. Regarding nervous system diseases, it is of utmost importance to select those cases in which HTLV-1 infection could really be associated. This is particularly true for patients from endemic areas and for HIV-infected patients and drug users, since that these groups are at a higher risk for HTLV infection. This caution in selecting neurological patients for HTLV diagnostic tests is justified by the fact that in some circumstances the seropositivity may merely represent an epiphenomenon. In this paper we enroll some neurological conditions that have been associated with HTLV-1/2 infection in the literature and discuss the real need for HTLV-1/2 diagnostic tests in each one. Because HIV/HTLV-co-infected patients seem to be at an increased risk for neurological diseases development, a special consideration about this matter is also made.

Upregulation of HTLV-1 and HTLV-2 expression by HIV-1 in vitro

Co-infections with HIV-1 and the human T leukemia virus types 1 and 2 (HTLV-1, HTLV-2) occur frequently, particularly in large metropolitan areas where injection drug use is a shared mode of transmission. Recent evidence suggests that HIV-HTLV co-infections are associated with upregulated HTLV-1/2 virus expression and disease. An in vitro model of HIV-1 and HTLV-1/2 co-infection was utilized to determine if cell free HIV-1 virions or recombinant HIV-1 Tat protein (200-1,000 ng/ml) upregulated HTLV-1/2 expression and infectivity. Exposure to HIV-1 increased the number of HTLV-1 antigen expressing cells, from 6% at baseline to 12% at 24 hr, and 20% at 120 hr (P < 0.05) post-exposure. A similar, although less robust response was observed in HTLV-2 infected cells. HIV-1 co-localized almost exclusively with HTLV-1/2 positive cells. Exposure to HIV-1 Tat protein (1,000 ng/ml) increased HTLV-1 p19 expression almost twofold by 48 hr, and cells co-stimulated with 10 nM phorbol myristate acetate (PMA) showed almost a fourfold increase over baseline. It is concluded that HIV-1 augments HTLV-1/2 infectivity in vitro. The findings also suggest a role for the HIV-1 Tat protein and PMA-inducible cellular factors, in HIV-1 induced HTLV-1/2 antigen expression.

T CD4+ cells count among patients co-infected with human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus type 1 (HTLV-1): high prevalence of tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM)

INTRODUCTION: HIV positive patients co-infected with HTLV-1 may have an increase in their T CD4+ cell counts, thus rendering this parameter useless as an AIDS-defining event. OBJECTIVE: To study the effects induced by the co-infection of HIV-1 and HTLV-1 upon CD4+ cells. MATERIAL AND METHODS: Since 1997, our group has been following a cohort of HTLV-1-infected patients, in order to study the interaction of HTLV-1 with HIV and/or with hepatitis C virus (HCV), as well as HTLV-1-only infected asymptomatic carriers and those with tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM). One hundred and fifty HTLV-1-infected subjects have been referred to our clinic at the Institute of Infectious Diseases "Emílio Ribas", São Paulo. Twenty-seven of them were also infected with HIV-1 and HTLV-1-infection using two ELISAs and confirmed and typed by Western Blot (WB) or polymerase chain reaction (PCR). All subjects were evaluated by two neurologists, blinded to the patient's HTLV status, and the TSP/HAM diagnostic was based on the World Health Organization (WHO) classification. AIDS-defining events were in accordance with the Centers for Disease Control (CDC) classification of 1988. The first T CD4+ cells count available before starting anti-retroviral therapy are shown compared to the HIV-1-infected subjects at the moment of AIDS defining event. RESULTS: A total of 27 HIV-1/HTLV-1 co-infected subjects were identified in this cohort; 15 already had AIDS and 12 remained free of AIDS. The median of T CD4+ cell counts was 189 (98-688) cells/mm³ and 89 (53-196) cells/mm³ for co-infected subjects who had an AIDS-defining event, and HIV-only infected individuals, respectively (p = 0.036). Eight of 27 co-infected subjects (30%) were diagnosed as having a TSP/HAM simile diagnosis, and three of them had opportunistic infections but high T CD4+ cell counts at the time of their AIDS- defining event. DISCUSSION: Our results indicate that higher T CD4+ cells count among HIV-1/HTLV-1-coinfected subjects was found in 12% of the patients who presented an AIDS-defining event. These subjects also showed a TSP/HAM simile picture when it was the first manifestation of disease; this incidence is 20 times higher than that for HTLV-1-only infected subjects in endemic areas.

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.

HTLV-2 infection in injection drug users in King County, Washington

Human T-cell lymphotropic virus type 2 (HTLV-2) is endemic in injection drug users (IDU), and native American populations in the Americas. Transmission is associated with high-risk injection and sexual practices. A cohort of 2561 IDU in King County, Washington completed 2 study visits over 1 y. HTLV-2 infection was detected in 190 (7.4%) of 2561 IDU, and 13 (7.8 cases per 1000 person-y) incident infections occurred during the study. Prevalent infection was associated with female gender, non-white race, longer duration as IDU, having a tattoo, combined injection of heroin and cocaine, and with serologic evidence of hepatitis B and C infection. Seroconversion was more common in women, and was associated with African American race, heterosexual identity and longer duration as IDU. In conclusion, increased risk of HTLV-2 infection was associated with non-white race, and injection drug of choice, suggesting injection networks may play an important role in transmission of HTLV-2. The high correlation of HTLV-2 infection with HCV infection suggests the major route of transmission in IDU is via injection practices. Additional studies are needed to examine the clinical manifestations of HTLV-2 infection, as well as the clinical and virological manifestations of HTLV-2/HCV coinfection.

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.

Tropical Spastic Paraparesis/Human T Leukemia Virus Type 1--Associated Myelopathy in HIV Type 1--Coinfected Patients

BACKGROUND

Tropical spastic paraparesis/human T leukemia virus type 1 (HTLV-1)-associated myelopathy (TSP/HAM) is rarely reported in the United States. The causative agents of TSP/HAM are HTLV-1 and, possibly, its cosmopolitan variant, human T leukemia virus type 2 (HTLV-2). Among HTLV-1- or HTLV-2-monoinfected individuals, the estimated lifetime risk for development of TSP/HAM is <2%. However, it has been suggested that HIV/HTLV coinfection may increase the risk for development of TSP/HAM.

METHODS

A total of 2239 human immunodeficiency virus (HIV)-infected patients were tested for HTLV-1 and HTLV-2 infection at the New Orleans Outpatient Clinic (Louisiana) during the period 1991-1998. HTLV-1-infected patients with suspected myelopathy were referred for additional evaluation.

RESULTS

Four cases of TSP/HAM (9.7%) were identified among 41 individuals with Western blot-confirmed HTLV-1 infection. The diagnosis was confirmed with use of molecular diagnostic assays and viral isolation. No TSP/HAM cases were identified among 65 patients with HIV-HTLV-2 coinfection. An additional patient with HIV-HTLV-1 coinfection also received a diagnosis of TSP/HAM at the New Orleans Veteran's Affairs HIV Outpatient Clinic (Louisiana). All patients had normal CD4+ T cell counts at the time of diagnosis.

CONCLUSIONS

Given the high rates of HIV-HTLV coinfection in the United States, a heightened suspicion for TSP/HAM should be considered in HIV-infected patients who present with normal CD4+ T cell counts and myelopathy in the absence of other acquired immunodeficiency syndrome-defining conditions.

Sarcoidosis and HTLV-1 infection

An asymptomatic, homosexual, white man was found to have an abnormal chest x ray. A presumptive diagnosis of sarcoidosis was made, but pulmonary function tests and a transbronchial biopsy were normal. He then remained asymptomatic for 10 years until he developed a progressive spastic paraparesis. At this point, antibodies to human T cell lymphotropic virus type 1 (HTLV-1) were identified in the serum and cerebrospinal fluid, and the diagnosis of HTLV-1 associated myelopathy was made, the history suggesting sexual exposure to HTLV-1 many years previously. HTLV-1 is associated with a spectrum of immune related disorders, including a pulmonary sarcoid-like syndrome. Infection with this chronic proinflammatory retrovirus should be considered in the differential diagnosis of all immune disorders in at risk individuals.

Mielorradiculopatia esquistossomótica

A mielorradiculopatia esquistossomótica é a forma ectópica mais grave e incapacitante da infecção pelo Schistosoma mansoni. A sua prevalência em área endêmica tem sido subestimada. O diagnóstico baseia-se na presença de sintomas neurológicos decorrentes de lesões da medula espinhal em nível torácico baixo e/ou lombar alto, na demonstração da infecção esquistossomótica por técnicas microscópicas ou sorológicas e na exclusão de outras causas de mielite transversa. O tratamento precoce, com esquistossomicidas e corticoesteróides, mostra-se eficaz na maioria dos casos e os pacientes não tratados não se recuperam ou morrem. Não há consenso sobre doses e duração do tratamento, mas estudo recente sugere que os corticoesteróides devam ser usados por pelo menos seis meses. Como o diagnóstico é presuntivo e o tratamento essencialmente clínico, há que se manter alerta para a presença da doença, aperfeiçoar a propedêutica e, dessa forma, evitar-se a laminectomia rotineira. Com o advento da ressonância magnética da medula espinhal houve grande avanço no diagnóstico da esquistossomose medular. Como conseqüência, o número de casos de mielopatia esquistossomótica relatados tem aumentado rapidamente.

Human T-lymphotropic virus type II and neurological disease

Human T-lymphotropic virus type I (HTLV-I) and type II (HTLV-II) are closely related retroviruses with similar biological properties and common modes of transmission. HTLV-I infection is endemic in well-defined geographic regions, and it is estimated that some 20 million individuals are infected worldwide. Although most infected individuals are asymptomatic carriers, some 2 to 5% will develop a chronic encephalomyelopathy, HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In contrast with HTLV-I, the role of HTLV-II in the development of neurological disorders is much less clear. HTLV-II is endemic in many native Amerindian groups and epidemic in injecting drug users (IDUs) worldwide. To evaluate the role of HTLV-II in neurological disease, we have critically reviewed all reported cases of HTLV-II-associated disorders. This has confirmed that although rare infection is associated with a disorder clinically similar or identical to HAM/TSP. However, most reports that have attributed infection to a range of other neurological disorders are difficult to evaluate in that in many cases either the association appears to be fortuitous or the presentations were confounded by a background of concomitant human immunodeficiency virus-1 infection and/or active IDU. In view of the many HTLV-II-infected individuals in urban areas of North America and Europe, neurologists should be aware of the potential clinical consequences of this infection.

The peripheral nerve complications of human immunodeficiency virus (HIV) infection

Peripheral nerve complications occurring in patients with human immunodeficiency virus (HIV) infection are frequent and challenging. This review discusses these various complications according to the degree of advancement of HIV disease. Particular emphasis is placed upon emerging causes of neuropathy found in the context of HIV disease, such as infection with hepatitis C and human T-lymphotropic virus type I, as well as neuropathies related to antiretroviral medications.

Quantification of HTLV type I and HIV type I DNA load in coinfected patients: HIV type 1 infection does not alter HTLV type I proviral amount in the peripheral blood compartment

Several reports suggest that HTLV-I/HIV coinfection may be associated with an increased risk of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In HTLV-I-monoinfected patients, the occurrence of HAM/TSP is associated with high peripheral blood HTLV-I proviral load. Using a real-time quantitative PCR assay, we assessed the proviral DNA load in peripheral blood mononuclear cells (PBMCs) from 15 asymptomatic HTLV-I-monoinfected patients, 15 HTLV-I-monoinfected patients with HAM/TSP, and 25 HTLV-I/HIV-1 coinfected patients, including 4 with HAM/TSP. We also measured HIV-1 proviral DNA load in PBMCs from the coinfected patients. The median HTLV-I proviral loads were 6,800 and 4,100 copies per 10(6) PBMCs in the asymptomatic monoinfected and coinfected groups, and 58,800 and 43,300 copies per 10(6) PBMCs in the monoinfected and coinfected patients with HAM/TSP, respectively. The difference between HTLV-I proviral loads in HAM/TSP and asymptomatic monoinfected patients was statistically significant (p < 0.0001), but there was no difference between the HTLV-I-monoinfected and HTLV-I/HIV-1-coinfected groups. There was no correlation between HTLV-I and HIV-1 proviral load. HTLV-I proviral load did not correlate with the CD4+ T lymphocyte count. Among patients with no HTLV-I disease, the median copy number of HTLV-I per 10(6) circulating CD4+ T cells was 114,000 in the coinfected group and 16,700 in the monoinfected group, but the difference was not significant (p = 0.089). These data do not confirm the hypothesis in which HIV-1 coinfection would increase HTLV-I proviral burden in the PBMCs. However, depletion of the CD4+ T cell subset, the main target of HTLV-I, could be counterbalanced by an up-regulation of HTLV-I replication or by greater resistance of HTLV-I-infected cells to HIV-1-induced destruction.

Mielopatia transversa em adulto portador de leucemia aguda linfoblástica: relato de caso

Relatamos um caso de mielopatia transversa aguda em paciente masculino de 31 anos de idade, branco, portador de leucemia aguda linfoblástica, subtipo L3 (LLA-L3). Esta é uma forma grave de leucemia e compromete mais crianças em relação aos adultos. Menos de 1% dos pacientes leucêmicos apresentam complicações espinais. No paciente em estudo, a sintomatologia instalou-se de modo abrupto e com as seguintes características: dores nas costas, paraplegia crural flácida e perda das funções sensitivas e vegetativas abaixo do segmento afetado. O diagnóstico etiológico foi estabelecido após a realização dos seguintes exames: hemograma, mielograma, análise do líquido cefalorraqueano e ressonância magnética de coluna dorsal. Foi instituído tratamento específico, que não interferiu com a evolução fatal da doença.

Localization of retrovirus in the central nervous system of a patient co-infected with HTLV-1 and HIV with HAM/TSP and HIV-associated dementia

Persons co-infected with HTLV-1 and HIV are at increased risk for neurologic disease. These patients may develop HAM/TSP and/or HIV-associated dementia. In this study, we localized cells infected with retrovirus in the central nervous system (CNS) of a patient with both HAM/TSP and HIV-associated dementia. HTLV-1 was localized to astrocytes and HIV to macrophage/microglia. There was no co-infection of a single cell phenotype in this patient. These data suggest that mechanisms other than co-infection of the same CNS cell may play a role in the development of neurologic disease in patients dual infected with HTLV-1 and HIV.

Differential patterns of interaction between HIV type 1 and HTLV type I in monocyte-derived macrophages cultured in vitro: implications for in vivo coinfection with HIV type 1 and HTLV type I

The interaction between human immunodeficiency virus type 1 (HIV-1) and human T cell leukemia-lymphoma virus type I (HTLV-I) has generated substantial interest. However, there is disagreement on the in vivo consequences of the double infection. We investigated the interactions between HIV-1 and HTLV-I in monocyte-derived macrophages cultured in vitro. For study, the T cell-tropic strain IIIB and the macrophagetropic strain Ada-M of HIV-1 were used. The HTLV-I was prepared from the supernatants of the virus-producing MT-2 cell line. We found that coinfection of macrophages with T cell-tropic HIV-1 and HTLV-I significantly enhanced HIV-1 replication, whereas double infection of the cells with macrophage-tropic HIV-1 and HTLV-I resulted in marked upregulation of HTLV-I production. Stimulatory interactions between HIV-1 and HTLV-I were mediated by their trans-acting proteins. Results of study on nuclear translocation of proviral DNA showed that the tax gene product of HTLV-I was able to facilitate the nuclear import of the reverse-transcribed HIV-1(IIIB) DNA. In contrast, the HIV-1 Tat protein did not increase the intranuclear trafficking of HTLV-I DNA, which suggests another mechanism for HTLV-I enhancement by the tat gene product. In conclusion, this study provides possible mechanisms whereby coinfection of an individual with HIV-1 and HTLV-I may influence the clinical outcome of double infection.

Morphine effects on HTLV-I infection in the presence or absence of concurrent HIV-1 infection

Human T-cell leukemia virus type I (HTLV-I) infection is emerging as an important complication in HIV infection and AIDS in injecting drug users. HIV-1 and HTLV-I share a common host in CD4+ T lymphocytes. However, the result of HIV-1 infection is the decimation of this cell population, whereas a hallmark of HTLV-I infection is the inappropriate proliferation of infected cells. Combined epidemiologic data suggest that HTLV-I infection is enhanced during concurrent HIV-1/HTLV-I infection; however, there are currently no in vitro studies focusing on the effects of drugs of abuse on retrovirus coinfection. We have found that in an in vitro coinfection system (HIV-1 + HTLV-I), morphine treatment further enhanced the levels of HTLV-I p19. In addition, indicators of in vitro infection by cell-free HIV-1 were reduced by morphine treatment in both single and dual in vitro infection experiments. Interleukin 2 levels in the affected cultures were found to increase with combined HTLV-I infection and morphine treatment. These in vitro results indicate the need to further explore the activity of HTLV-I within opiate-treated cells, as this oncoretrovirus appears to be especially sensitive to morphine-induced alterations to its host cell environment.

HTLV-I-associated myelopathy/tropical spastic paraparesis in Brazil: a nationwide survey. HAM/TSP Brazilian Study Group

To study the epidemiology of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in Brazil, we conducted a nationwide survey between March 1994 and April 1995. Five centers from three regions of the country participated, enrolling 163 patients. Most patients came from the northeastern and southeastern regions (93.2%). Most enrollees were white women, 42.9% and 64.4%, respectively. The most common risk factors for infection included a history of venereal diseases (30.6%) and blood transfusion (21.6%). The median age at the beginning of the disease was 42 years. The main neurologic findings were spastic paraparesis, widespread brisk tendon jerks, bilateral Babinski's sign, and bladder dysfunction. Some interregional differences reached statistical significance. The ratio of females over males increased from south to north. In addition, in both southern and southeastern regions, whites prevailed, whereas in the northeast, mulattos predominated. This follows the normal distribution of the population in these regions. A significantly higher rate of venereal diseases was found in the southeast compared with the other regions studied. A history of intravenous drug use was more frequent among patients as the sample moves south. Finally, a fluctuating course of the disease was proportionally more frequent in the southern region.

Coinfection with HTLV-I and HIV: increase in HTLV-I-related outcomes but not accelerated HIV disease progression?

Human T-lymphotropic virus type I (HTLV-I) and HTLV-II have been postulated to accelerate disease progression in patients coinfected with HIV. However, recent evidence suggests that HTLV-II has no effect on HIV disease progression. In addition, it has recently been reported that HIV viral load was not increased in subjects coinfected with HTLV-I, suggesting that the biologic basis for the hypothesis does not exist. Several recent studies in Brazil, however, suggest that coinfection with HTLV-I and HIV has substantial medical consequences. For example, coinfection was associated with a higher CD4 lymphocytes count following adjustment for HIV viral load or HIV clinical stage. In addition, coinfected subjects have a high prevalence of clinical significant myelopathy. The effect of other putative viruses as cofactors in HIV disease progression is also discussed.

AIDS-associated vacuolar myelopathy

AIDS-associated vacuolar myelopathy (VM) is a common neurologic complication of AIDS. Pathologically, VM is characterized by vacuolization in the lateral and posterior columns of the thoracic spinal cord and has a striking similarity with the myelopathy of vitamin B12 deficiency. In autopsy series, 20% to 55% of patients with AIDS have evidence of spinal cord disease consistent with VM. The myelopathy usually manifests late in the course of HIV infection, with slowly progressive weakness of the lower extremities, gait disorder, sensory abnormalities in the legs, impotence in men, and urinary frequency and urgency. Its course is invariably progressive and leads to severe paralysis of the lower limbs, with loss of the ability to walk and of sphincter control. The differential diagnosis is extensive and includes metabolic, infective, and neoplastic spinal cord diseases. The diagnosis is based on the clinical observation and the exclusion of other causes of myelopathy via serologic, radiographic, and cerebrospinal fluid studies. The pathogenesis of VM is unknown. Attempts to detect HIV in the spinal cord have not yielded significant results, and there is no evidence of a relationship between the presence of HIV and the development of myelopathy. A metabolic disorder of the vitamin B12-dependent transmethylation pathway, induced by HIV or cytokine activation, is considered the possible cause of VM associated with AIDS. There is no known treatment for AIDS myelopathy and there is no evidence that antiretroviral drugs can improve the symptoms or slow the progression of VM. The symptomatic treatment includes antispasticity agents, management of sphincter dysfunction, and physical therapy. Experimental treatments are being tested in clinical trials.