The virulence-enhancing factor of mucins. 2. Fractionation studies on hog gastric mucin

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Abstract
Preliminary fractionations have been carried out on prepns. from fresh hog stomach linings for a factor responsible for the virulence-enhancing power for bacteria. Crude blood-group substance prepared by autolysis had virulence-enhancing activity which, in the same samples, did not run parallel with the blood-group activity. Dialysis at 0[degree] at pH 4.2 separated a small amt. of active insoluble material from inactive soluble blood-group mucoid; the latter was precipitated in a semi-pure state by ethanol, More of this active material was prepd. directly from fresh linings and further purified. The still heterogeneous active material contained nitrogen (Dumas) 14.5-13.5%; in aqueous suspensions, which were non-viscous, different batches consistently had activities 7-9 times those of the crude blood-group substance. This activity, however, was increased 3- to 4-fold when suspended in a completely inactive 3.5% (w/v) soln. of semi-pure blood-group substance (see above), which imparts a marked viscosity to the suspension. This viscosity was of the same order as that of the original active crude blood-group-substance soln.; a concn. of activity of 25-30 times is therefore implied. The same marked increase in activity was produced by suspending the active material in tragacanth and agar solns. to give suspensions with approx. the same viscosity at 37[degree] as the above. The virulence-enhancing power of hog gastric mucin is due to a virulence-enhancing factor which is active alone. But it only manifests its full activity when in combination with a 2d inert factor or factors, which may well act by providing a viscous medium for its suspension.