Structural Features of Geminiviruses - The most surprising features of this virus group are the small capsid size, 18^-20 nm x 30 nm, their geminate (paired particles) morphology, which sets them apart from all other classes of viruses, and the unexpected covalently closed circular topography of the single stranded DNA which is in the molecular weight range of 7 x 10⁵ to 9 X 10⁵.

All geminiviruses recognized so far have a single major coat protein subunit in the range of 2.7-3.4 x 10⁴ daltons. The genome of the geminiviruses consists of either one or two circular, single stranded DNA molecules.

The single stranded viral DNA, 2.6 to 3.0 kb long, is converted in the nucleus of plant cells into a double stranded replicative form by an as yet unknown mechanism.

This indicates that the BGMV DNA is heterogeneous and has a divided genome consisting of two DNA molecules of approximately the same size, but differing in genetic content.

It would appear that geminiviruses consist of two populations of paired particles, differing only in the nucleotide sequence of the DNA molecules they contain. Transmission of the virus in nature occurs by leafhoppers or the tropical whitefly.