Mathematical analysis of the global dynamics of a HTLV-I infection model, considering the role of cytotoxic T-lymphocytes

A mathematical model for the CD8+ T-cell response to Human T cell leukemia/lymphoma virus type I (HTLV-I) infection is investigated in this paper. The proposed model, which involves four coupled nonlinear ordinary differential equations, describes the interaction of uninfected CD4+T cells, latently infected CD4+T cells, actively infected CD4+T cells and HTLV-I specific cytotoxic T-lymphocytes (CTLs). Our model exhibits three biologically feasible equilibria, namely infection-free steady state, HTLV-I free steady state and an endemic steady state. Our mathematical analysis establishes that the local and global dynamics are determined by the two threshold parameters R-0 and R1, basic reproduction number for HTLV-I viral infection and for CTL response, respectively. For R-0 < 1, the infection-free steady state E-0 is globally asymptotically stable, and HTLV-I viruses are cleared. For R-1 <= 1 < R-0, the HTLV-I free singular point E-1 is globally asymptotically stable, and the HTLV-I infection becomes chronic but no CTL response can be established, and most of the HTLV-I infected individual remains as an asymptomatic carrier. Mathematical analysis shows that a unique endemic steady state E* is globally asymptotically stable for R-1 > 1 in the interior of the feasible region. We perform the sensitivity analysis to find out the key parameters of the HTLV-I infection model with respect to R-0 and R-1. Implications of our findings to the dynamics of CTL response to HTLV-I infections in vivo and pathogenesis of HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) are discussed. (C) 2020 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.

Automated summary

This study investigates a mathematical model for the CD8+ T-cell response to HTLV-I infection, revealing three biologically feasible equilibria and showing that the local and global dynamics are determined by the threshold parameters R-0 and R1. The model predicts different outcomes for HTLV-I response and infection based on the values of R-0 and R1, highlighting the importance of these parameters in understanding the dynamics of CTL response to HTLV-I infections in vivo.