Spatial dynamics of Hepatitis B virus with its δ-satellite and defective interfering particles
Document typeMaster thesis
Rights accessOpen Access
This project provides an indepth analysis of the spatio-temporal dynamics of the system Hepatitis B Virus (HBV) - Hepatitis Delta Virus (HDV) - Defective interfering particles (DIPs). HDV is a virus satellite that co-infects hepatocytes together with HBV. That is, the satellite is a kind of parasite of HBV. On the other hand, DIPs are incomplete viruses that typically interfere with the replication of the standard virus (i.e., HBV). About the dynamics of interference of DIPs on standard viruses, few is known about the antagonistic interactions between the three virus types studied here. The computational model and the results reported in this research project are an extension of the mean field model developed and analysed in the Bachelor Thesis done by the author of this work. We have introduced two key processes that are extremely important in virus dynamics: physical space and stochasticity. As far as we know, this project presents the first attempt to model the spatial dynamics of HBV together with its delta satellite and DIPs. To do so we work with a computational model given by a stochastic Cellular Automaton (CA), which is a dynamical system that evolves in discrete time steps. The present work identifies the dynamics characterised by the mean field model studied in the Bachelor's Thesis with the spatial model, and provides a more realistic biological setting characterizing the bifurcations and the impact of space and parameters in the critical values as well as providing results on the spatial spread of the three viral populations and characterize spatial self-organization patterns. We have found that the satellite is very sensitive to spatial dynamics, observing a wide parameter ranges for which they are not able to persist. This result has an important clinical implication, since the presence of satellite replication together with HBV is known to cause larger damage to hepatocites. Our results show how the state-transition probabilities affect the satellite persistence.