Abstract
Following the intratracheal injection into horses of virulent pneumococci of the 3 fixed types in broth cultures, there develops frequently a massive pleural effusion either as a purely local phenomenon or associated with underlying pulmonary consolidation grossly resembling lobar pneumonia, the pleural surfaces of the animals showing all the gross and microscopic evidence of an acute serofibrinous inflammation with the presence of as many as 30 litres of exudate at a time. This exudate besides showing the cellular products of inflammation contains viable pneumococci corresponding to the type injected intratracheally. We have accordingly attempted to immunize horses with this exudate, using ascending doses of the material intravenously. By this method we have been able to produce potent antisera to Type I, and Type II organisms as tested by the mouse protection method. With Type III pleural exudate the resulting antiserum has exhibited same protective value but this has been uniformly low.
The production of type specific antisera by this method presents certain advantages which seem to favor its use in preference to the methods at present in practice. Thus after the exudate has been withdrawn under sterile conditions from the infected animal the material is stored in the ice-box in its native state to be later used in the required dosage for immunization of the serum-producing animals. This naturally lessens the numerous technical steps that are necessary for preparing the immunizing doses of the organism by the present methods.
Besides the technical ease of preparing the antiserum the facto r of the length of time taken to produce a potent product is important. From the result of our present observations we are led to believe that this will be materially shortened by this newer method.
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