Purification, characterization and serological detection of virus-like particles associated with banana bunchy top disease in Australia

Isometric virus-like particles, 18 nm in diameter, have been isolated from banana (Musa spp.) affected by bunchy top disease in Australia. Banana bunchy top disease-associated virus-like particles (BBTV) banded as a single component with buoyant density of 1-28 to 1.29 g/ml in Cs2SO4 and sedimented atabout 46S in isokinetic sucrose density gradients. The A260/.42S 0 of purified preparations was about 1-33. A single coat protein of Mr 20 500 was identified with antibodies to BBTV particles from Australia. Single-stranded DNA of about 1 kb as well as ssRNA smaller than 0-45 kb was also associated with the particles. A polyclonal antiserum to BBTV, suitable for use in ELISA, was prepared. Stability and antigenicity of purified BBTV was impaired by storage at pH>i 8-5 and freezing at-20 °C without protectants. BBTV was detected by double antibody sandwich-ELISA with monoclonal and polyclonal antibodies, in field-infected banana plants, single aphids from an infective colony, and in experimentally aphid-inoculated banana plants. After transmission of BBTV particles by aphids from a banana bunchy top disease-affected to an uninfected banana plant, the disease was induced and BBTV was detected by ELISA in symptomatic leaves only. BBT