Virus density distribution as a function of genotype considered as a continuous
variable and of time is studied with a nonlocal reaction-diffusion equation taking into
account virus competition for the host cells and its elimination by the immune
response and by the genotype-dependent mortality. The existence of virus strains,
that is, of positive stable stationary solutions decaying at infinity, is determined by
the admissible intervals in the genotype space where the genotype-dependent
mortality is less than the virus reproduction rate, and by the immune response under
some appropriate assumptions on the immune response function characterizing virus
elimination by immune cells. The competition of virus strains is studied,
first, without immune response and then with the immune response. In the
absence of immune response, the strain dynamics is different in a short time
scale where they converge to some intermediate slowly evolving solutions
depending on the initial conditions, and in a long time scale where their
distribution converges to a stationary solution. Immune response can essentially
influence the strain dynamics either stabilizing them or eliminating one of the
strains. An antiviral treatment can also influence the competition of virus
strains, and it can lead to the emergence of resistant strains, which were
absent before the treatment because of the competition with susceptible
strains.
Keywords
virus density distribution, genotype, nonlocal interaction,
competition of strains