Can anyone suggest a program to use to calculate synonymous versus non-synonymous nucleotide changes? Jon Clewley Virus Reference Division Central Public Health Laboratory 61 Colindale Avenue London NW9 5HT United Kingdom Phone: 0181 200 4400 Fax: 0181 200 1569 or: 0181 200 7874 Email: jclewley at hgmp.mrc.ac.uk