This diagram is adapted from Roux and Raoult (1), although not to scale. It shows the phylogenetic classification of the genus Rickettsia based upon sequence comparisons of OmpB genes. The colored boxes enclose monophyletic groups or clades within the genus. For more information on the various species, click on the appropriate species name.
Although MIF testing has been the serologic gold standard, we are now prototype-testing custom-assembled Profiles IgG ELISA assays with 4-8 native antigens in series and tested simultaneously with screen-positive sera. Coating antigens are OmpB + OmpA, an optimal mix to differentiate reactive species. We are interested in collaborations with reference laboratories in different regions of the world.
Rickettsia amblyommii was placed within the blue-outlined clade on the basis of OmpB sequence comparison.
Rickettsia monacensis is located in a separate clade between the green-outlined and yellow-outlined clades with Rickettsia buchneri, a tick endosymbiont (2).
1) Roux, V. & D. Raoult, 2000. Phylogenetic analysis of members of the genus Rickettsia using the gene encoding the outer-membrane protein rOmpB (ompB). Int. J. Syst. Evol. Microbiol. 50: 1449-1455.
2) Kurtii, T., R. Felsheim, N. Burkhardt, J. Oliver, C. Heu and U. Munderloh, 2015. Rickettsia buchneri sp. nov., a rickettsial endosymbiont of the blacklegged tick Ixodes scapularis. Int J Sys Evol Microbiol 65: 965-970.