ABSTRACT
The comovirus group was compiled by the ICTV in 1971. Properties of comoviruses have been reviewed by van Kammen and Mellema, Bruening, Stace-Smith, Matthews, and Francki and co-workers. Cytoplasmic vacuolate-vesiculate inclusions and crystalline inclusions of virus particles were suggested as main characteristics of the group. Blockage of xylem elements by large aggregates of comovirus particles and the presence of vacuolate-vesiculate and crystalline inclusions are proposed here as being diagnostic for comovirus infections. Broad bean true mosaic virus was assigned to the comovirus group, under the name true broad bean mosaic virus, as a possible member. Large cytoplasmic inclusions near nuclei in cowpea epidermal cells are interpreted to be the vacuolate-vesiculate inclusions characteristic of comovirus infections, and they stain magenta in Azure A. Red clover mottle virus has been classified as a member of the comovirus group.
