Human T-Lymphotropic virus type 1 infection in absence of tax gene: A challenge for molecular diagnosis.

Sebastián Blanco, María Celia Frutos, Marcos César Balangero, Sandra Verónica Gallego

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 2021 Jun

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This is the first report of HTLV-1 infection without detectable tax gene. Even though the tax gene of HTLV-1 presents high genetic stability, in the case presented here no sequence of tax was detected by three different and widely used molecular assays targeting several sequences of the gene. Nevertheless, HTLV-1 pol and env genes and LTR region were properly detectable. Several PCRs targeting tax sequences have been developed and largely used for molecular diagnosis of HTLV infection since the tax gene of HTLV-1 is known to be well preserved and intolerant to changes or mutations. In the case reported here, molecular detection of the virus was challenging. HTLV prevalence is complex and in many regions remains unknown. The identification of HTLV-infected individuals is important to determine its actual prevalence and design strategies to reduce viral spread. The finding and communication of HTLV-1 defective-provirus strains is important and necessary to guide the selection of representative target sequences on HTLV genome to design molecular assays, highlighting that different sequences should be combined to ensure adequate diagnosis. The latter is especially relevant in cases when discordant results between serological and molecular assays. This report contributes to the knowledge of the overall molecular epidemiology of HTLV-1 and encourages the need of surveillance of HTLV-1 "missed tax gene profiles" and the evaluation of the impact of these defective viral variants on molecular diagnosis and human health. Copyright © 2021 Elsevier B.V. All rights reserved.

Citation

Sebastián Blanco, María Celia Frutos, Marcos César Balangero, Sandra Verónica Gallego. Human T-Lymphotropic virus type 1 infection in absence of tax gene: A challenge for molecular diagnosis. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases. 2021 Jun;90:104765