Table 4. Bioinformatic and Laboratory Evidence for a Functional Rickettsiales vir Homolog (rvh) T4SS.
| Vir1 | Conservation2 | Rvh3 | Size4 | Evidence5 |
| B4 | 100 | B4a | 805 | A, B, G |
| B4b | 810 | C, D, G | ||
| B10 | 100 | B10 | 483 | A, D, G, H |
| B11 | 100 | B11 | 334 | A, D, E, H |
| B9 | 97 | B9a | 250 | E, G |
| B9b | 158 | A, D, Fa, G, H | ||
| D4 | 92 | D4 | 591 | D, G, H |
| B6 | 90 | B6a | 426 | |
| B6b | 407 | B, G | ||
| B6c | 425 | Fa, Fb, G | ||
| B6d | 420 | B, Fa, Fb, G | ||
| B6e | 389 | Fa, Fb, G | ||
| B8 | 90 | B8a | 232 | C, D |
| B8b | 243 | A, C, D, E, G | ||
| B1 | 53 | B1* | 252 | |
| B5 | 52 | — | — | — |
| B2 | 37 | B2* | 123 | |
| B3 | 37 | B3 | 95 | |
| B7 | 23 | B7* | 59 | C, D, Fa, Fb |
Vir and Vir-like proteins, following the nomenclature of the A. tumefaciens vir system.
Percentage of 62 bacterial T4SSs that contain each Vir or Vir-like protein [29].
Rickettsiales vir homolog. Proteins previously not annotated as Vir via consensus annotation are noted with an asterisk.
Average size of the Rickettsia orthologs across 13 genome sequences. Numbers for RvhB6a-e show only the VirB6/TrbL domains; avg, lengths of full sized RvhB6 proteins are as follows: RvhB6a = 1055 aa; RvhB6b = 674 aa; RvhB6c = 971 aa; RvhB6d = 886 aa; RvhB6e = 1154 aa.
Laboratory studies demonstrating putative function. A = gene expression analysis of R. conorii [213]; B = gene expression analysis of R. prowazekii [214]; C = gene expression analysis of R. typhi [215]; D = bacterial two-hybrid screen of R. sibirica [74]; E = proteome analysis of R. felis [216]; Fa = PhoA fusion analysis of R. typhi [99]; Fb = gene expression analysis of PhoA fusion positive proteins of R. typhi [99]; G = proteome analysis of R. prowazekii str. Madrd E [217]; H = Differential translation analysis between R. prowazekii strains Madrid E and Breinl [218].