Mulitscale Modeling of HIV Transmission Dynamics

Objective: The research objective is to develop a multiscale HIV immunoepidemiological model to study the within host HIV viral and immune dynamics at the individual level and correlate to the community level HIV transmission dynamics at the population level.

Background: The viral loads in HIV infected individuals have correlation with their risk of transmission, and this relationship needs to be better understood. Epidemiological models generally assume uniform transmissibility for all patients in the population. However, the effect of the within host immune response to disease transmission is incompletely understood. Although both within host and between hosts HIV dynamic models have been studied individually, understanding behaviors occurring across scales by developing multiscale models is novel and significant.

Methods: HIV immunoepidemiological multiscale model has two scales: within host and between hosts. The within host scale of the model simulates the immune response to HIV virus, through differential equations. The model encompasses target CD4 T cells, infected cells, and virus populations. Then, the model is used to understand the therapeutic impact of different HIV drugs, reverse transcriptase inhibitors and protease inhibitors on immunological and clinical outcomes.

Results: The compartmental formulation demonstrates no correlation between disease free equilibrium and viral set point, which is a relatively stable level of virus in the body. However recovery of CD4 cells through antiretroviral therapy is observed to be a function of the disease free equilibrium.

Discussion: After calibrating the model with experimental data from target population, the next phase is building a network of people in which the transmissibility of HIV+ individuals is a function of their viral load, which is the outcome of the within host immune response model. By connecting within host and between host scales through a multiscale model, we will develop novel predictions and decisions for outbreak control.