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.