TABLE 1.

Definitions of variables used for estimating mutation rates

Symbol(s)	Definition
μs/n/c	Mutation rate as substitutions per nucleotide per cell infectiona
μs/n/r	Mutation rate as substitutions per nucleotide per strand copyinga
f, fs	Observed mutation frequency and observed mutation frequency for substitutions only, respectivelya
T, Ts	Total no. of mutations observable with a given detection method (mutational target size); subscript s is used to refer to substitutions onlya
L	Length (in nucleotides) of the genetic region studied
c	No. of cell infection cycles
B	No. of viral progeny particles released per infected cell (burst size, or viral yield)
N0	No. of viral particles that start an infection (inoculum size)
N1	No. of viral particles after growth
a	Exponential growth rate
W	Relative fitness as determined from growth rates and/or burst sizes
s	Fitness effect of a mutation, defined as 1 − W
E(sv)	Average s value of single random nucleotide substitutions, excluding lethal ones
pL	Probability that a single random nucleotide substitution is lethal
α	Selection correction factor
P0	Fraction of cultures showing no mutants in the Luria-Delbrück fluctuation test (null class)
m	Mutation rate to a given phenotype per strand copying obtained from the Luria-Delbrück fluctuation testa
r, rc	No. of cycles of copying and no. of cycles of copying per cell infection, respectively
δ	Ratio of indels to total mutations (indel fraction)

^aA subscript i is used analogously to refer to indels.