Patent ID: 6887483

Claim:
A method of making a mutant endotoxin comprising: culturing a non-typeable Haemophilus influenzae strain having a mutation in htrB gene, wherein the htrB mutation produces a mutant non-typeable Haemophilus influenzae having a mutant endotoxin containing a decreased phosphoethanolamine content and an increased hexose content in the mutant endotoxin's inner core, and a pentaacylated or tetraacylated lipid A lacking one or two secondary acyl chains compared to the corresponding wild-type non-typeable Haemophilus influenzae hexaacylated endotoxin, and wherein the mutant endotoxin has substantially reduced toxicity as compared to the hexaacylated endotoxin of the wild-type non-typeable Haemophilus influenzae ; and purifying the mutant endotoxin.