Table 3.

Comparison of pros and cons for three methods of the propagation of VEEV stocks.

Population Type	Pros	Cons
Uncloned (wild-type)	- Maintenance of wild-type diversity	- Cell culture adaptation often results in artificial amino acid substitutions and in vivo attenuation - Risk that multiple major variants present in the population can confound identification of genetic determinants of important phenotypes - Limited supply without additional passages
Plaque-cloned	- Clear consensus sequence (verified by sequencing original population) and lack of multiple variants	- Possible reduced single nucleotide polymorphism diversity - Risk of selection of a suboptimal fitness mutant (change in the consensus and master sequence) - Limited supply without additional passages
cDNA-cloned	- Clear consensus sequence (verified by sequencing the first-generation population) and lack of multiple major variants - Unlimited supply of the same master virus without passages	- Possible reduction in single nucleotide polymorphism diversity