Table 1. Parameter definitions.

	number of trimers on virion
	probability that virion has trimers
	fraction of dominant negative Env-mutant encoding plasmids
	fraction of antibody-resistant Env-mutant encoding plasmids
	probability of forming a “functional” trimer in the entry assay,
	probability of forming a “functional” spike in the neutralization assay, see equation (1)
	number of “functional” trimer on virion
	number of trimer-receptor interactions needed for entry
	number of antibodies-Env interactions required to neutralize one spike
	variance coefficient (imperfect transfection model)
	segregation coefficient ranging from 0 (no segregation) to 1 (full segregation)
	maximal distance of trimers required for cooperation in an infective cluster
	Number of trimers for which infectivity is 1/2
	softness parameter (Hill coeficient) in the soft threshold model