Abstract
Astrovirus serotype 4 has increased in relative prevalence in the Oxford, UK area in 1993. The structural gene of human astrovirus serotype 4 has been sequenced and the results indicate that this protein differs substantially from serotypes 1 and 2. In particular, conservation at the C terminus is greatly reduced. However, amino acid substitutions in this region show a strong conservation in character suggesting that structural or functional constraints operate in this region.