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Liability to hydrophobic and charge interaction of smooth Salmonella typhimurium 395 MS sensitized with anti-MS
Abstract:
Sensitization of smooth Salmonella typhimurium 395 MS bacteria with hyper-immune anti-MS immunoglobulin G (IgG) antibodies increased the liability to hydrophobic interaction as assessed by the affinity for a column of Octyl-Sepharose. After sensitization, the material originally eluted with 1 M (NH4)SO4 in a 0.01 M phosphate buffer (pH 6.8) was not desorbed until the ionic strength was reduced to nil, and 0.1% (vol/vol) Triton X-100 in the 0.01 M phosphate buffer was used as eluant. Furthermore, by including positively charged bis-trimethylamino-polyethylene glycol (PEG) or negatively charged bis-sulfoamino-PEG in an aqueous two-phase system of dextran T500 and PEG 6000, the partition of the IgG-sensitized bacteria was affected by either of the polymers, whereas that of the parent bacteria was not. The hydrophobic effect of IgG binding was enhanced by complement. With heat-inactivated complement, the effect of IgG was diminished. The F(ab')2 fragment showed a much lower capacity to promote a hydrophobic interaction than the complete IgG molecule.
Insights
Hyper-immune anti-Salmonella typhimurium immunoglobulin G (IgG) antibodies increased bacterial hydrophobicity. This enhanced interaction was influenced by complement and polyethylene glycol (PEG) polymers.
Area of Science:
- Microbiology and Immunology
- Surface Chemistry and Biophysics
Background:
- Salmonella typhimurium is a significant bacterial pathogen.
- Immunoglobulin G (IgG) antibodies are crucial for adaptive immunity.
- Bacterial surface properties influence host-pathogen interactions.
Purpose of the Study:
- To investigate the effect of anti-Salmonella typhimurium IgG sensitization on bacterial hydrophobicity.
- To determine how complement and polymer interactions modulate this hydrophobic effect.
Main Methods:
- Hydrophobic interaction chromatography using Octyl-Sepharose.
- Analysis of bacterial partitioning in aqueous two-phase systems with charged polyethylene glycol (PEG) polymers.
- Assessment of IgG fragment (F(ab')2) effects on hydrophobicity.
Main Results:
- IgG sensitization significantly increased Salmonella typhimurium hydrophobicity, requiring altered elution conditions.
- Charged PEG polymers differentially affected the partitioning of IgG-sensitized bacteria, but not parent bacteria.
- Complement enhanced the hydrophobic effect of IgG binding, while heat-inactivated complement diminished it.
- The F(ab')2 fragment exhibited a reduced capacity to promote hydrophobic interactions compared to intact IgG.
Conclusions:
- Antibody sensitization profoundly alters bacterial surface hydrophobicity.
- This change in hydrophobicity is modulated by host factors like complement and can be influenced by polymer interactions.
- The Fc region of IgG plays a significant role in mediating these hydrophobic effects.