Effects of HTLV-1 on leukocyte trafficking and migration in ACs compared to healthy individuals.

Human T-lymphotropic virus type 1 (HTLV-1) is a RNA virus belonging to Retroviridae family and is associated with the development of various diseases, including adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Aside from HAM/TSP, HTLV-1 has been implicated in the development of several disorders that mimic auto-inflammation. T-cell migration is important topic in the context of HTLV-1 associated diseases progression. The primary objective of this case-control study was to assess the relationship between increased mRNA expression in virus migration following HTLV-1 infection. PBMCs from 20 asymptomatic patients and 20 healthy subjects were analyzed using real-time PCR to measure mRNA expression of LFA1, MLCK, RAC1, RAPL, ROCK1, VAV1 and CXCR4. Also, mRNA expression of Tax and HBZ were evaluated. Mean expression of Tax and HBZ in ACs (asymptomatic carriers) was 0.7218 and 0.6517 respectively. The results revealed a noteworthy upregulation of these genes involved in T-cell migration among ACs patients in comparison to healthy individuals. Considering the pivotal role of gene expression alterations associated with the progression into two major diseases (ATLL or HAM/TSP), analyzing the expression of these genes in the ACs group can offer probable potential diagnostic markers and aid in monitoring the condition of ACs.

High level of genomic divergence in orf-I p12 and hbz genes of HTLV-1 subtype-C in Central Australia.

BACKGROUND: Human T cell lymphotropic virus type 1 (HTLV-1) infection remains a largely neglected public health problem, particularly in resource-poor areas with high burden of communicable and non-communicable diseases, such as some remote populations in Central Australia where an estimated 37% of adults are infected with HTLV-1. Most of our understanding of HTLV-1 infection comes from studies of the globally spread subtype-A (HTLV-1a), with few molecular studies reported with the Austral-Melanesian subtype-C (HTLV-1c) predominant in the Indo-Pacific and Oceania regions. RESULTS: Using a primer walking strategy and direct sequencing, we constructed HTLV-1c genomic consensus sequences from 22 First Nations participants living with HTLV-1c in Central Australia. Phylogenetic and pairwise analysis of this subtype-C proviral gDNA showed higher levels of genomic divergence in comparison to previously published HTLV-1a genomes. While the overall genomic homology between subtypes was 92.5%, the lowest nucleotide and amino acid sequence identity occurred near the 3' end of the proviral genome coding regulatory genes, especially overlapping hbz (85.37%, 77.46%, respectively) and orf-I product p12 (82.00%, 70.30%, respectively). Strikingly, the HTLV-1c genomic consensus sequences uniformly showed a defective translation start codon for the immune regulatory proteins p12/p8 encoded by the HTLV-1A orf-I. Deletions in the proviral genome were detected in many subjects, particularly in the structural gag, pol and env genes. Similarly, using a droplet digital PCR assay measuring the copies of gag and tax per reference host genome, we quantitatively confirmed that provirus retains the tax gene region at higher levels than gag. CONCLUSIONS: Our genomic analysis of HTLV-1c in Central Australia in conjunction with earlier Melanesian HTLV-1c sequences, elucidate substantial differences with respect to the globally spread HTLV-1a. Future studies should address the impact these genomic differences have on infection and the regionally distinctive frequency of associated pulmonary disease. Understanding the host and virus subtype factors which contribute to the differential morbidity observed, is crucial for the development of much needed therapeutics and vaccine strategies against this highly endemic infection in remote First Nations communities in Central Australia.

Cannabinoid receptors as new targets for HTLV-1 associated myelopathy (HAM/TSP) treatment.

BACKGROUND/AIM: The roles of endocannabinoids are described in immune modulation and neuroprotection. HTLV-1-associated myelopathy (HAM/TSP) is an inflammatory neurodegenerative disease. Therefore, in this study, the interactions of HTLV-1 regulatory factors and host cannabinoid receptors (CBRs) were evaluated in HAM/TSP. METHODS: Nineteen HAM/TSPs, 22 asymptomatic carriers (ACs), and 18 healthy controls (HCs) were enrolled. RNA was extracted from PBMCs and then reverse-transcribed to cDNA. The gene expression of CB1R and CB2R, as well as HTLV-1 proviral load (PVL), Tax and HTLV-1 basic leucine zipper factor (HBZ) were assessed by RT-qPCR. RESULTS: The mean expression of CB1R in ACs (8.51 ± 2.76) was significantly higher than HAMTSPs (1.593 ± 0.74, p = 0.05) and also HCs (0.10 ± 0.039, p = 0.001). The CB2R gene expression level in ACs (2.62±0.44) was significantly higher than HAM/TSPs (0.59 ± 0.15, p = 0.001) and HCs (1.00 ± 0.2, p = 0.006). Meanwhile there was a strong correlation between CB1R and CB2R gene expression levels in the HCs and HAM/TSPs (p = 0.001). HTLV-1-Tax expression in HAM/TSPs (386 ± 104) was higher than ACs (75 ± 32) and statistically significant (p = 0.003). While HTLV-1-HBZ was only expressed in three AC subjects and five HAM/TSPs, thus it cannot be analyzed. CONCLUSION: The up-regulation of CB2R has immunomodulatory effects in inflammatory reactions. While CB1R as a neuroprotective agent may suppress inflammatory reactions in ACs, preventing HAM/TSP. It seems that, like multiple sclerosis (MS), cannabinoid medications are beneficial in HAM/TSP.

Preclinical assessment of an anti-HTLV-1 heterologous DNA/MVA vaccine protocol expressing a multiepitope HBZ protein.

BACKGROUND: Human T-lymphotropic virus 1 (HTLV-1) is associated with the development of several pathologies and chronic infection in humans. The inefficiency of the available treatments and the challenge in developing a protective vaccine highlight the need to produce effective immunotherapeutic tools. The HTLV-1 basic leucine zipper (bZIP) factor (HBZ) plays an important role in the HTLV-1 persistence, conferring a survival advantage to infected cells by reducing the HTLV-1 proteins expression, allowing infected cells to evade immune surveillance, and enhancing cell proliferation leading to increased proviral load. METHODS: We have generated a recombinant Modified Virus Vaccinia Ankara (MVA-HBZ) and a plasmid DNA (pcDNA3.1(+)-HBZ) expressing a multiepitope protein based on peptides of HBZ to study the immunogenic potential of this viral-derived protein in BALB/c mice model. Mice were immunized in a prime-boost heterologous protocol and their splenocytes (T CD4+ and T CD8+) were immunophenotyped by flow cytometry and the humoral response was evaluated by ELISA using HBZ protein produced in prokaryotic vector as antigen. RESULTS: T CD4+ and T CD8+ lymphocytes cells stimulated by HBZ-peptides (HBZ42-50 and HBZ157-176) showed polyfunctional double positive responses for TNF-α/IFN-γ, and TNF-α/IL-2. Moreover, T CD8+ cells presented a tendency in the activation of effector memory cells producing granzyme B (CD44+High/CD62L-Low), and the activation of Cytotoxic T Lymphocytes (CTLs) and cytotoxic responses in immunized mice were inferred through the production of granzyme B by effector memory T cells and the expression of CD107a by CD8+ T cells. The overall data is consistent with a directive and effector recall response, which may be able to operate actively in the elimination of HTLV-1-infected cells and, consequently, in the reduction of the proviral load. Sera from immunized mice, differently from those of control animals, showed IgG-anti-HBZ production by ELISA. CONCLUSIONS: Our results highlight the potential of the HBZ multiepitope protein expressed from plasmid DNA and a poxviral vector as candidates for therapeutic vaccine.

Pathogenesis of HTLV-1 infection and progression biomarkers: An overview

ABSTRACT Infection by human T-cell lymphotropic virus type 1 (HTLV-1) occurs in lymphocytes, which travel throughout the body, thus affecting several target organs and causing varied clinical outcomes, particularly in populations that are underserved and do not have access to healthcare. However, the mechanism of pathogenesis is not yet fully understood. The TAX and HTLV-1 basic leucine zipper factor (HBZ) proteins maintain viral persistence and affect pathogenesis through cell proliferation and immune and inflammatory responses that accompany each clinical manifestation. TAX expression leads to inhibition of transcription error control, OX40 overexpression, and cell proliferation in adult T-cell leukemia (ATL). OX40 levels are elevated in the central nervous system (CNS), and the expression of TAX in the CNS causes neuronal damage and loss of immune reactivity among patients with HTLV-1-associated myelopathy (HAM). HBZ reduces viral replication and suppresses the immune response. Its cell compartmentalization has been associated with the pathogenesis of HAM (cytoplasmic localization) and ATL (nuclear localization). TAX and HBZ seem to act antagonistically in immune responses, affecting the pathogenesis of HTLV-1 infection. The progression from HTLV-1 infection to disease is a consequence of HTLV-1 replication in CD4+ T and CD8+ T lymphocytes and the imbalance between proinflammatory and anti-inflammatory cytokines. The compartmentalization of HBZ suggests that this protein may be an additional tool for assessing immune and inflammatory responses, in addition to those already recognized as potential biomarkers associated with progression from infection to disease (including human leukocyte antigen (HLA), killer immunoglobulin-like receptors (KIR), interleukin (IL)-6, IL-10, IL-28, Fas, Fas ligand, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and mannose-binding lectin).