The non-canonical Brucella Lipopolysaccharide (LPS) does not activate the Prophenoloxidase Activating (proPO) system

Galleria mellonella larvae (n = 5) were inoculated with live bacteria (A and B): 106 Colony Forming Units (CFU)/larva of Klebsiella pneumoniae 52145 (Kp) and Brucella suis bv2 (Bs2); or purified LPS (C): 5 μg/larva of LPS from Pseudomonas aeruginosa PAO1 (PsLPS) and 10 μg/larva of LPS from Brucella abortus 2308W (BaLPS), Brucella melitensis 16M (BmLPS) and Brucella microti CCM4915 (BmiLPS); both experiments including a PBS-injected group. Larva haemolymph was extracted at 1, 3 and/or 6 h post-inoculation and their absorbance measured at 400 nm wavelength. Differences between values of each sample versus PBS were considered significant at p < 0.05 (*), p < 0.005 (**) and p < 0.0005 (***)