Mapping variants in HTLV-1 genome to analyze their impacts on the HAM/TSP development: A systematic review.

The reasons that lead some individuals living with the Human T Lymphotropic Virus 1 (HTLV-1) to develop HAM/TSP are still unclear. To better understand the viral genetic factors that may be associated with the development of HAM/TSP, this study aims to evaluate the impact of HTLV-1 genome mutations on the development of this disease through a systematic review. This review followed the PRISMA guidelines and was registered in the PROSPERO database. The search for articles was performed in PMC, PubMed, Lilacs, SciELO, and Embase databases using the following search descriptors: HTLV-1, HAM/TSP, mutation, polymorphism, genetic variation, and sequenc*. From the 1,929 articles found in the search, 20 were selected according to the pre-defined inclusion and exclusion criteria. A total of 619 HAM/TSP cases were compared with 555 AC controls. The mutations possibly related to the disease progression were detected in hbz (R119Q), tax (A7959V), ORF-I (R88K, P86S, S69G, P45L, L40F, C39R, CR9Y), and gp46 (V247I, N93D, S72G) genetic regions. The data collected and analyzed here indicate that mutations in the HTLV-1 genome could play an important role in the chronic inflammatory state and may be related to the development of HAM/TSP.

An overview of sequencing technology platforms applied to HTLV-1 studies: a systematic review.

Human T-lymphotropic virus type 1 (HTLV-1) was the first human retrovirus described. The viral factors involved in the different clinical manifestations of infected individuals are still unknown, and in this sense, sequencing technologies can support viral genome studies, contributing to a better understanding of infection outcome. Currently, several sequencing technologies are available with different approaches. To understand the methodological advances in the HTLV-1 field, it is necessary to organize a synthesis by a rigorous review. This systematic literature review describes different technologies used to generate HTLV-1 sequences. The review follows the PRISMA guidelines, and the search for articles was performed in PubMed, Lilacs, Embase, and SciELO databases. From the 574 articles found in search, 62 were selected. The articles showed that, even with the emergence of new sequencing technologies, the traditional Sanger method continues to be the most commonly used methodology for generating HTLV-1 genome sequences. There are many questions that remain unanswered in the field of HTLV-1 research, and this reflects on the small number of studies using next-generation sequencing technologies, which could help address these gaps. The data compiled and analyzed here can help research on HTLV-1, assisting in the choice of sequencing technologies.

Molecular characterization of HTLV-1 genomic region hbz from patients with different clinical conditions.

The human T-cell lymphotropic virus type-1 (HTLV-1) is associated with severe pathologies, such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), adult T-cell leukemia-lymphoma (ATLL), and infective dermatitis associated with the HTLV-1 (IDH). Interestingly, HTLV-1 infection does not necessarily imply the development of pathological processes and it is unknown why some patients remain asymptomatic carriers (AC). Despite some mutations in the HTLV-1 genome appear to influence the outcome of HTLV-1, there are few studies that characterize molecularly the hbz region. This study aimed to perform the molecular characterization of hbz gene isolated from patients with different clinical outcomes. A total of 15 sequences were generated and analyzed with 571 sequences previously published. The analises showed that the R119Q mutation seems to be related to HTLV-1 clinical conditions since the frequency of this HBZ mutation is significantly different in comparison between AC with HAM/TSP and ATLL. The R119Q mutation is possibly a protective factor as the frequency is higher in AC sequences.