Serology of the BYV particles in crude extracts from infectedTetragonia expansa negatively stained with aqueous uranyl acetate pH 4.3. (a) Decoration plus immunogold labelling of a virus particle with antiserum specific to the p22 (major CP); note nonlabelled 'p24-tail'. (b) Specific decoration by antiserum specific to the p24 (minor CP) at the 75 nm 'tail' on a complete particle. (c) Selected particle ends showing specific decoration or immunogold labelling, respectively, of the 75 nm 'tails' by the antiserum specific to the p24. Bar represents 300 nm.