A Virus Made from Parts of the Genomes of Brome Mosaic and Cowpea Chlorotic Mottle Viruses

Brome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV) are spherical plant viruses which have recently been shown to possess divided genomes (Lane & Kaesberg, 1971; Bancroft, 1971) even though the virus particles sediment as single species. BMV contains four species of RNA with molecular weights of 1.09 x 10⁶, 0.99 x 10⁶, 0.75 x 10⁶ and 0.28 x 10⁶ and CCMV contains four species with molecular weights of 1.15, 1.0, 0.85 and 0.32 x 10⁶ (Fowlks & Young, 1970). The species are named 1, 2, 3 and 4, respectively. Species 1 + 2 + 3 are required to initiate BMV infections (Lane & Kaesberg, 1971) but CCMV seems only to require species 1 + 2, although the addition of species 3 enhances lesion production (Bancroft, 1971). Species 4 is needed by neither virus for infection. I wished to determine if a virus possessing some properties of both viruses could be obtained by mixing BMV species 1 + 2 with CCMV species 3 prior to biological assay.