Skip to main content
Figure 1 | BMC Evolutionary Biology

Figure 1

From: Barriers to antigenic escape by pathogens: trade-off between reproductive rate and antigenic mutability

Figure 1

Threshold for invasion by rare antigenic variant into a population at equilibrium for a dominant variant. The y axis in each plot shows the maximum cost, δ/β, that an invading variant can carry and still succeed in invasion; lower values correspond to more stringent conditions for invasion by a rare type and greater scope for dominance by the common type. The x axis shows R0 = β/(1 + α). R0 is the basic reproductive number of the pathogen – the average number of new infections caused by a single infection in a fully susceptible host population [23]. The four curves in each panel show values of γ = 0.1, 0.3, 0.5, 1.0 from bottom to top. Because of the nondimensional scaling of time used for rate parameters, faster death rate, or decay of memory, reduces all parameters by the same scaling factor. The consequences of a greater death rate are shown approximately by moving from the lower right panel to the upper left panel along the diagonal, in which invasion by a rare type becomes more difficult. Faster decay of memory reduces the benefit to the rare type by reducing the relative frequency of S1, the hosts that carry memory against the dominant type. Thus, hosts with shorter generation times are more likely to support pathogens that maintain antigenic dominance over long periods of time.

Back to article page