João Gabriel Ramos Ribas

Learn More
Human T-cell leukemia virus type 1 (HTLV-1), the first human retrovirus to be discovered, is present in diverse regions of the world, where its infection is usually neglected in health care settings and by public health authorities. Since it is usually asymptomatic in the beginning of the infection and disease typically manifests later in life, silent(More)
After the first description of TSP/HAM in 1985 and the elaboration of WHO's diagnostic criteria in 1988, the experience of the professionals in this field has increased so that a critical reappraisal of these diagnostic guidelines was considered timely. Brazilian neurologists and observers from other countries met recently to discuss and propose a modified(More)
HTLV-1 associated myelopathy/ tropical spastic paraparesis (HAM/TSP) is a systemic immune-mediated inflammatory disease and tissues other than nervous can be damaged, mainly ocular, rheumatic and dermatologic. Over 90% of HTLV-1-infected individuals remain lifelong asymptomatic and this retrovirus persists indefinitely in their CD4+ T-lymphocytes. The(More)
HTLV-I/II infection is present in all regions of Brazil, but its prevalence varies according to the geographical area, being higher in Bahia, Pernambuco and Pará. It has been estimated that Brazil has the highest absolute number of infected individuals in the world. Blood donors screening and research conducted with special groups (indigenous population of(More)
The development of HTLV-1-associated myelopathy (HAM/TSP) in HTLV-1-infected individuals is probably a multi-factor event, in which the immune system plays a crucial role. The efficiency of the host immunity seems to be one of the in vivo determining factors of the proviral load levels and is regulated by genes associated with MHC class I alleles (HLA).(More)
Schistosoma mansoni infection is likely to be responsible for a significant proportion of cases of myelopathy occurring in areas where schistosomiasis is endemic. The aim of this study is to describe the clinical, laboratory and therapeutic data of 23 patients with schistosomal myeloradiculopathy. The medical records of 23 patients with schistosomal(More)
Although it is believed widely that distinct patterns of the host immune response are associated with the outcome of chronic human T cell lymphotropic virus type 1 (HTLV-I) infection toward asymptomatic or symptomatic neurodegenerative myelopathy (HAM/TSP), the exact mechanism underlying these immunological events still remains unknown. In this study, we(More)
BACKGROUND HTLV-1 proviral load is a risk marker for HAM/TSP, but it is insufficient to determine the disease outcome. HTLV-1 Tax and HBZ proteins have been implicated in HAM/TSP pathogenesis in inducing cell proliferation and cytotoxic T lymphocytes response. OBJECTIVES To quantify the expression of tax and HBZ mRNA in asymptomatic carriers (AC) and HAM(More)
INTRODUCTION HTLV-1/2 screening among blood donors commonly utilizes an enzyme-linked immunosorbent assay (EIA), followed by a confirmatory method such as Western blot (WB) if the EIA is positive. However, this algorithm yields a high rate of inconclusive results, and is expensive. METHODS Two qualitative real-time PCR assays were developed to detect(More)
The human T-cell lymphotropic virus type 1 (HTLV-1) is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HT). Although it is widely believed that virus infection and host immune response are involved in the pathogenic mechanisms, the role of the immune system in the development and/or maintenance of HT remains unknown. We(More)