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

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.

Neuroepidemiology of transverse myelitis and its etiologies in Latin America: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Transverse myelitis (TM) is a rare neuro-inflammatory condition of the spinal cord that can cause chronic and debilitating symptoms reducing quality of life. TM is understudied in developing regions worldwide, particularly in Latin America and the Caribbean (LAC), where the prevalence of TM is unknown. Etiologies of TM are variable, but certain infectious, autoimmune or nutritional abnormalities may be more common in LAC with differing estimated prevalences of these etiologies. Given the paucity of data available on TM in LAC, we conducted a systematic review of the literature and meta-analysis to estimate the prevalence of TM and its etiologies in LAC.

METHODS

We conducted a comprehensive literature search in English, Spanish and Portuguese language databases for TM studies in LAC that included at least ≥ 5 cases of TM, published after 2010. We extracted data on TM frequency, etiologies, and diagnostic tools utilized for the diagnosis from each included article. A meta-analysis was conducted to estimate the proportion of TM and various TM etiologies across articles.

RESULTS

No studies were found that reported the prevalence of TM in LAC or in an individual country. A total of 99 studies were included, with autoimmune (MS, NMO/NMOSD) and infectious etiologies (HTLV-1, arboviruses) most reported. Brazil (53 studies) had the most studies on TM, followed by Mexico (16) and Argentina (15). A total of 26,992 people were included in the meta-analysis, from which the estimated proportion of TM in LAC based on all included studies was 0.47 (95%CI 0.39-0.56) using a random effects model. The utility of MRI spine, lumbar puncture, and disease-specific serological/CSF markers together to diagnose TM was utilized in only 18% of studies.

DISCUSSION

This review highlights important gaps in identifying the community prevalence of TM in LAC with no articles examining the disease's specific frequency. By understanding the epidemiology of TM, its associated etiologies, and barriers to its diagnosis in LAC, there is potential to improve treatment access and disability outcomes for those in the region affected by the disease.

HIV-1 3'-Polypurine Tract Mutations Confer Dolutegravir Resistance by Switching to an Integration-Independent Replication Mechanism via 1-LTR Circles

Several recent studies indicate that mutations in the human immunodeficiency virus type 1 (HIV-1) 3'polypurine tract (3'PPT) motif can reduce sensitivity to the integrase inhibitor dolutegravir (DTG). Using an in vivo systematic evolution of ligands by exponential enrichment (SELEX) approach, we discovered that multiple different mutations in this viral RNA element can confer DTG resistance, suggesting that the inactivation of this critical reverse transcription element causes resistance. An analysis of the viral DNA products formed upon infection by these 3'PPT mutants revealed that they replicate without integration into the host cell genome, concomitant with an increased production of 1-LTR circles. As the replication of these virus variants is activated by the human T-lymphotropic virus 1 (HTLV-1) Tax protein, a factor that reverses epigenetic silencing of episomal HIV DNA, these data indicate that the 3'PPT-mutated viruses escape from the integrase inhibitor DTG by switching to an integration-independent replication mechanism. IMPORTANCE The integrase inhibitor DTG is a potent inhibitor of HIV replication and is currently recommended in drug regimens for people living with HIV. Whereas HIV normally escapes from antiviral drugs by the acquisition of specific mutations in the gene that encodes the targeted enzyme, mutational inactivation of the viral 3'PPT sequence, an RNA element that has a crucial role in the viral reverse transcription process, was found to allow HIV replication in the presence of DTG in cell culture experiments. While the integration of the viral DNA into the cellular genome is considered one of the hallmarks of retroviruses, including HIV, 3'PPT inactivation caused integration-independent replication, which can explain the reduced DTG sensitivity. Whether this exotic escape route can also contribute to viral escape in HIV-infected persons remains to be determined, but our results indicate that screening for 3'PPT mutations in patients that fail on DTG therapy should be considered.

Human T-Lymphotropic virus type 1 and human immunodeficiency virus co-infection in rural Gabon

Introduction

Human T-cell lymphotrophic virus type-1 (HTLV-1) and human immunodeficiency virus (HIV-1) co-infection occur in many populations. People living with HIV-1 and infected with HTLV-1 seem more likely to progress rapidly towards AIDS. Both HTLV-1 and HIV-1 are endemic in Gabon (Central Africa). We investigated HTLV-1 and HIV-1 co-infection in the Haut-Ogooué province, and assessed factors that may favor the rapid evolution and progression to AIDS in co-infected patients.

Methods

Plasma samples from HTLV-1 patients were tested using ELISA, and positive samples were then tested by western blot assay (WB). We used the polymerase chain reaction to detect HTLV-1 Tax/Rex genes using DNA extracted from the buffy coat of ELISA-positives samples.

Results

We recruited 299 individuals (mean age 46 years) including 90 (30%) men and 209 (70%) women, all of whom are under treatment at the Ambulatory Treatment Centre of the province. Of these, 45 were ELISA HTLV-1/2 seropositive. According to WB criteria, 21 of 45 were confirmed positive: 20 were HTLV-1 (44%), 1 was HTLV-1/2 (2%), 2 were indeterminate (4%) and 22 were seronegative (49%). PCR results showed that 23 individuals were positive for the Tax/Rex region. Considering both serological and molecular assays, the prevalence of HTLV-1 infection was estimated at 7.7%. Being a woman and increasing age were found to be independent risk factors for co-infection. Mean CD4+ cell counts were higher in HTLV-1/HIV-1 co-infected (578.1 (± 340.8) cells/mm³) than in HIV-1 mono-infected (481.0 (± 299.0) cells/mm³) Individuals. Similarly, the mean HIV-1 viral load was Log 3.0 (± 1.6) copies/ml in mono-infected and Log 2.3 (± 0.7) copies/ml in coinfected individuals.

Conclusion

We described an overall high prevalence of HTLV-1/HIV-1 co-infection in Gabon. Our findings stress the need of strategies to prevent and manage these co-infections.

Distribution of Human Immunodeficiency Virus and Human T-Leukemia Virus Co-infection in Bahia, Brazil

Human Immunodeficiency Virus (HIV) and Human T-Leukemia Virus (HTLV) are retroviruses that share similar routes of transmission. In Brazil, the prevalence of HIV and HTLV varies according to geographic region. The state of Bahia, located in the Northeast region, is considered endemic for both retroviruses. The present study aimed to characterize the frequency of HIV/HTLV coinfection and evaluate the geographic distribution of coinfection throughout the state. This cross-sectional study was conducted at the state's Central Laboratory of Public Health (LACEN-BA) and included all samples from 2004 to 2013 submitted to serological testing for anti-HIV and anti-HTLV-1/2, screened by chemiluminescence/ELISA and confirmed by Western blot. Infection rates are expressed as the number of infected individuals per 100,000 inhabitants from each municipality. A total of 129,158 samples originating from 358/417 (85.8%) municipalities in Bahia were evaluated. HTLV was detected in 2.4% of the HIV-positive samples (n = 42) compared to 0.5% of those with negative HIV serology (n = 677) (OR: 4.65; CI: 3.39–6.37). HIV/HTLV coinfection was more frequent in women (69.0%); the median age of coinfected individuals was 47.2 years [interquartile range (IQR): 41.6–55.4 years]. In the 14/417 (3.4%) municipalities where at least one case of HIV/HTLV coinfection was detected, the overall HTLV coinfection rate in HIV-positive samples was 0.25 (range: 0.17–13.84) per 100,000 inhabitants. Most cases of HIV/HTLV-1 coinfection (21/37, 57%) were concentrated in the municipality of Salvador. Isolated instances (one or two cases) of HIV/HTLV-1 coinfection were distributed across municipalities known to be endemic for HTLV infection.

Clonality of HIV-1- and HTLV-1-Infected Cells in Naturally Coinfected Individuals

BACKGROUND

Coinfection with human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus type 1 (HTLV-1) diminishes the value of the CD4+ T-cell count in diagnosing AIDS, and increases the rate of HTLV-1-associated myelopathy. It remains elusive how HIV-1/HTLV-1 coinfection is related to such characteristics. We investigated the mutual effect of HIV-1/HTLV-1 coinfection on their integration sites (ISs) and clonal expansion.

METHODS

We extracted DNA from longitudinal peripheral blood samples from 7 HIV-1/HTLV-1 coinfected, and 12 HIV-1 and 13 HTLV-1 monoinfected individuals. Proviral loads (PVL) were quantified using real-time polymerase chain reaction (PCR). Viral ISs and clonality were quantified by ligation-mediated PCR followed by high-throughput sequencing.

RESULTS

PVL of both HIV-1 and HTLV-1 in coinfected individuals was significantly higher than that of the respective virus in monoinfected individuals. The degree of oligoclonality of both HIV-1- and HTLV-1-infected cells in coinfected individuals was also greater than in monoinfected subjects. ISs of HIV-1 in cases of coinfection were more frequently located in intergenic regions and transcriptionally silent regions, compared with HIV-1 monoinfected individuals.

CONCLUSIONS

HIV-1/HTLV-1 coinfection makes an impact on the distribution of viral ISs and clonality of virus-infected cells and thus may alter the risks of both HTLV-1- and HIV-1-associated disease.

Prevalence and Molecular Epidemiology of Human T-Lymphotropic Virus (HTLV) Infection in People Living With HIV/AIDS in the Pará State, Amazon Region of Brazil

The human T-lymphotropic virus (HTLV) is part of the group of retroviruses that share similar routes of transmission to the human immunodeficiency virus (HIV). Coinfection of these viruses can affect the clinical course of both infections, and reports have shown a quicker progression to AIDS and the development of HIV-related opportunistic infections. The current study investigated the demographic characteristics, prevalence, and the subtypes of HTLV among people living with HIV/AIDS (PLWHA) in the State of Pará, Northern Brazil. Blood samples were obtained from patients who were attending a reference unit that provides medical assistance to HIV-infected individuals in the State of Pará, Brazil, during the period of May 2016 to June 2017. Plasma samples were screened by ELISA tests to detect antibodies anti-HTLV-1/2. DNA and viral types were identified by real-time polymerase chain reaction (qPCR). All samples with viral DNA were submitted to nested PCR and nucleotide sequencing. The overall coinfection rate was 1.4% (5/368), and all samples were from subtype HTLV-1a. No cases of HTLV-2 infection were detected. The prevalence of HTLV-1 was higher in females (80%), individuals between 31 and 50 years of age, heterosexual, unmarried, with low monthly income, with secondary educational level or higher, sporadic condom usage, limited number of sexual partners, and no history of sexually transmitted infections. All samples from HTLV-1-infected patients were identified as strains belonging to the subtype 1a (Cosmopolitan), subgroup A (Transcontinental). This study identified that the prevalence of HIV/HTLV coinfection has dropped from 8 to 1.3% in the current investigation. There was a shift of HTLV subtype from a predominance of HTLV-2 infection in the past to an actual exclusively HTLV-1a. There was no significant association between economic, sociodemographic, and behavioral characteristics in HIV/HTLV coinfection.

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.

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.

SEROPREVALENCE OF HTLV IN A POPULATION OF HIV1-INFECTED PATIENTS IN MIDWESTERN BRAZIL

Human T-cell lymphotropic virus (HTLV) may affect the clinical course of human immunodeficiency virus 1 (HIV1). Both infections are common in endemic areas because these viruses share similar routes of transmission. The aim of this study was to estimate the seroprevalence of HTLV1/2 in a population of HIV1-infected patients in the state of Goiás, Midwestern Brazil. Of the 505 studied patients, four (0.79%) were positive for anti-HTLV1/2 by enzyme-linked immunosorbent assay (ELISA), with HTLV1 infection confirmed by line immunoassay (LIA) and polymerase chain reaction (PCR) in all of the ELISA-positive samples. No cases of HTLV2 infection were observed. The prevalence of HTLV1/HIV1 coinfection was 0.79% (4/505; 95% CI: 0.25-2.16). All the coinfected patients reported sexual risk behaviors and only one reported intravenous drug use. Sequencing of the viral long terminal repeat (LTR) region and phylogenetic analysis revealed that the four HTLV1 isolates belonged to the Transcontinental a subgroup of the Cosmopolitan (1a) subtype, the most frequent subgroup detected in Brazil. This study shows a low prevalence of HTLV1/2 in HIV1-infected patients in Midwestern Brazil.

Manifestations of HIV infection in the peripheral nervous system

Peripheral nerve disorders are associated with all stages of HIV infection. Distal sensory polyneuropathy is characterised by often-disabling pain that is difficult to treat. It is prevalent in both high-income and low-income settings. In low-income settings, use of potentially neurotoxic antiretrovirals, which are inexpensive and widely available, contributes substantially to incidence. Research has focused on identification of factors that predict risk of distal sensory polyneuropathy and elucidation of the multifactorial mechanisms behind pathogenesis. Sensorimotor polyneuropathies and polyradiculopathies are less frequent than distal sensory polyneuropathy, but still occur in low-income settings and have potentially devastating consequences. However, many of these diseases can be treated successfully with a combination of antiretroviral and immune-modulating therapies. To distinguish between peripheral nerve disorders that have diverse, overlapping, and frequently atypical presentations can be challenging; a framework based on a clinicoanatomical approach might assist in the diagnosis and management of such disorders.

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.