Figure 1.
Schematic representation of budding and lytic virus replication strategies.
On the left, budding viruses: a time after infection of the cell, sufficient epitopes are presented on the cell surface for CTL to recognise and kill the cell; virion production causes an increase in cell mortality,
, at a later time
; and at a later time
, virions begin to be shed from the cell at constant rate
. On the right, lytic viruses: beginning a time
after infection the cell becomes visible to CTL, after time
, stress induced by virus replication within the cell generates an additional mortality rate
; and the infected cell bursts and releases
virions a time
after infection. In both figures,
is the duration of a cell's visibility to CTL before virus release begins. Intervals between events are not shown to any scale.
Figure 2.
Dependence of infected cell growth rates on CTL numbers, for different virus replication strategies.
We compare the standard model (green) with models of a budding virus (black) and lytic (red) strategies. Parameters are chosen so that in the absence of CTL all models yield the same infected cell growth rate, expected lifetime, and for the lytic and budding strategies have the same window of visibility of infected cells to CTL, , before virus release begins. Parameter choices; growth rate in absence of CTL is
, equivalent to a doubling time of 16 hours; expected infected cell lifetime is 2 days;
; onset of virus shedding in the budding virus model is at
; death rate due to cytopathicity of lytic virus,
;
(new infected cells per virion).