Members of the order Legionellales can be molecularly distinguished from other Gammaproteobacteria by the presence of four conserved signature indels (CSIs) in the proteins tRNA-guanine(34) transglycosylase, lipoprotein-releasing system transmembrane protein lolE and tRNA (guanosine(37)-N1)-methyltransferase TrmD.[8]
^Fraser, D.W., Tsai, T,. Orenstein, W., et al. (1977). Legionnaires' disease: description of an epidemic of pneumonia. New England Journal of Medicine. 297:1189–1197.
^McDade, JE., Shepard, C.C., Fraser, D.W., et al., (1977) Legionnaires' Disease — Isolation of a Bacterium and Demonstration of Its Role in Other Respiratory Disease. New England Journal of Medicine. 297: 1197–1203.