Aim: To study toxicity of lypooligosaccharides (LOS) of non-typable Haemophilus influenzae (NTHi) strain and products of their detoxication obtained using different reagents.
Materials and methods: LPS was obtained from the NTHi strain grown on solid brain-heart infusion nutrient medium using previously described method of isolation and purification of LOS. Obtained LPS was treated in same conditions by one of the 3 detoxifying agents: anhydrous hydrazine (AH), alkali (NaOH), and hydrochloric hydroxylamine (HH). Toxicity of LOS and its detoxified derivatives was measured on outbred mice which were administered 0.5 ml of actinomycin D intraperitoneally 1 day before immunization. Death of animals was assessed on day 2 after immunization. Polyacrylamide gel electrophoresis was used for study the influence of detoxifying agents on physico-chemical properties of LOS.
Results: As a result of treatment of NTHi No.45 LOS by different detoxifying agents, 3 preparations of detoxified LOS (d-LOS) and 3 preparations from precipitates (nd-LOS) were obtained. Preparation d-LOSAH was the least toxic. Toxic properties of nd-LOSHH did not reliably change. PAAG electrophoresis showed that virtually all detoxified preparations were characterized by higher migration of lypooligosaccharide components compared to original LOS of NTHi No. 45, which indicates the lowering of LOS molecular weight after treatment by detoxifying agents, associated with elimination of lipid A higher fatty acids.
Conclusion: Analysis of effects of detoxifying agents indicates the need to select individual conditions for treatment by each of them.