TABLE 1.

Variables and parameters of the model.

Symbol	Description
pB—A	Coinfection probability for virus A
pA—B	Coinfection probability for virus B
c,cA,cB	Cost of the mini-CRISPR array
w,wA,wB	Viral productivity in a mixed coinfection
q,qA,qB	Probability that the virus survives when there is mutual targeting
xA,xB	Fraction of the viral population that harbors a mini-CRISPR array
P∗,P∗∗	Critical coinfection probabilities for the maintenance of a mini-CRISPR array

The cost of the mini-CRISPR array and the viral productivity in a mixed coinfection are defined in relation with the basal productivity in a pure infection.