Arch Virol (2002) 147: 1275–1285 DOI 10.1007/s00705-002-0819-1 Remarkable variability of apple mosaic virus capsid protein gene after nucleotide position 141 K. Petrzik 1 and O. Lenz 1,2 1 Department of Plant Virology, Academy of Sciences of the Czech Republic, ˇ Cesk´ e Budˇ ejovice, Czech Republic 2 Faculty of Biological Sciences, University of South Bohemia, ˇ Cesk´ e Budˇ ejovice, Czech Republic Received September 20, 2001; accepted February 26, 2002 Published online May 8, 2002 c  Springer-Verlag 2002 Summary. Eight new sequences of European isolates from almond, apple, hop, prune and pear of the Apple mosaic ilarvirus (ApMV) capsid protein gene are presented. A consensus sequence was established as having 654 nucleotides (nt) and two American and two European isolates were identified to have insertions 6 to 15 nucleotides after nt position 141. The insertion resulted in the American isolate A inframeshift repaired with two point insertions 17 and 68 nt downstream. The RNA around the insertion point can potentially form a stable secondary structure with three hairpins. The insertions could stabilise this structure or could be neutral. The predicted folding of the translated protein is not influenced by the insertions or frameshift, and we speculate that the region after nt position 141 is without reasonable selection pressure and represents a hot spot for the accumulation of insertion mutations in ApMV. Introduction Apple mosaic virus (ApMV) (family Bromoviridae, genus Ilarvirus) is present world-wide, preferentially on woody hosts such as blackberry, raspberry (Rubus sp.), apple (Malus sp.), apricot, cherry, almond, plum and peach (all Prunus sp.), hazelnut (Corylus avellana), roses (Rosa) and hop (Humulus lupulus) [5]. ApMV was also found in mountain ash (Sorbus aucuparia), silver birch (Betula pendula), horse chestnut (Aesculus hippocastanum) and red horse chestnut (A.x carnea) [16]. No insect vector is known and hence the virus is transmitted most prob- ably by pollen, by vegetative propagation from infected trees or by mechanical inoculation.