The mathematical modeling of the process of generation of HIV-1 strains that present the syncytium-inducing phenotype during the asymptomatic and clinical AIDS phases is proposed and discussed in this paper. These strains may utilize exclusively CXCR4 (X4 strains) or not (R5X4 strains or dual-tropic). The experimental basis of Shankarappa et al. (J Virol 1999; 73(2): 10489-502,) is used as a reference for the generation and parameter estimation of the phenomenological models. In this study, different mathematical models for the phenotypical evolution of HIV-1 in terms of the retroviral ability to induce syncytium formation are proposed, tested and discussed. Better adherence to experimental results is verified when reversibility between the SI and NSI phenotypes is considered. Moreover, better alignment to in-vivo dynamics is observed if time-dependent functions are assumed to model the mutation rate among the R5, R5X4 and X4 strains of HIV-1.
AIDS; Syncytium-inducing; Mathematical modeling
