Six functional groups covering 68 Vaccinia virion accessions: ‘7PC’ (seven protein complex), DNA, ‘membrane’ (MV transmembrane and membrane-associated proteins),’ structural’, ‘thiol’ (redox plus an additional glutaredoxin), transcriptosome (mRNA biogenesis).

‘#mem’ = number of members in each group, ‘#comb’ = number of pairwise combinations within a group according to n!/k!(n-k)! (subset of k distinct elements from an n-element set). There are 450 theoretical pairs of ‘membrane’ with ‘transcriptosome’-group proteins (these pairs being designated ‘non-rational’). Some accessions were reassigned during the study (eg. VP8 away from ‘DNA’). The ‘Membrane’ group was chosen to represent all MV proteins with detectable transmembrane domains plus MV proteins considered to be membrane-associated (A26, A27). Since WV-specific proteins were not considered in the current study, VENV (F13L), a membrane-associated WV-specific protein, was included in the search DB in error. A11 (a ‘VMAP’ [39]) is also considered to be not packaged in Vaccinia MV [2]. No XL at all for A14 and I2 were detected in this study. The Vaccinia stub of the cowpox ATI is considered, here, to be a membrane protein. VP8, a virion core protein, is included in the ‘DNA’ group due to its nucleic acid binding properties [40] as opposed to a known role in conjunction with the Vaccinia genome.