A drug-dependence mutation was
identified and introduced in a cDNA clone (2). Viruses recovered from this cDNA clone were grown and plated in the presence and
absence of the drug to estimate the fraction of revertants to drug sensitivity,
f = 1.6 ´ 10-4, and it was assumed that all revertants were
to the wild-type (T = Ts = 1) (1). Since the mutant was drug-dependent, it had
to be grown in the presence of the drug, and thus revertants to the wild-type
were lethal, i.e. ca = 1. Therefore, ms/n/c = 3 ´ 1.6 ´ 10-4 = 4.8 ´ 10-4.
However, reversion to drug sensitivity could be due mutations other than
reversion to the wild-type (T > 1)
and therefore, this represents probably an upper-limit estimate.
1. Drake, J. W. and J. J. Holland. 1999.
Mutation rates among RNA viruses. Proc. Natl. Acad. Sci. USA 96:13910-13913.
2. Wang, W., W. M. Lee, A. G. Mosser, and R. R. Rueckert.
1998. WIN 52035-dependent human rhinovirus 16: assembly deficiency caused by
mutations near the canyon surface. J Virol. 72:1210-1218.