Effect of Egg White in Oral Vaccination Against Pneumococcus.

The development of resistance to pneumococcus infection in young rats following the oral administration of various pneumococcus products has been reported by Ross. 1 Feeding of pneumococcus cultures to rats and rabbits was also done by Maeji 2 with similar results. That the mucous membrane of the gastro-intestinal tract is an effective site for the introduction of antigen, for the purpose of protecting the animal against pneumococcus infection, is also indicated in the work of Cooper 3 on sub-mucosal injection of vaccines in rabbits. Besredka 4 has shown that bile is useful in sensitizing or preparing the intestinal mucosa for the absorption of antigens; Arnold 5 and Finder 6 have investigated the effect of bile and egg-white on gastric secretion and on intestinal permeability to bacteria and antigens. The latter work shows that following the ingestion of egg-white and bile separately or in mixtures there is a definite lack of gastric response and an increased permeability of the small intestine.

The present work was undertaken (1) to confirm the experiments on oral immunization against pneumococci; (2) to simplify the procedure for producing an effective antigen in quantities suitable for human experiments; (3) to investigate the effect of preliminary preparation of the gastro-intestinal mucosa; and (4) to study the effect on pulmonary pneumococcus infections.

This report shows the effect of preparing the gastro-intestinal mucosa of the rat by feeding egg-white 30 minutes before the pneumococcus antigen is given. Young white rats of fairly uniform size (60-80 gm.) were fed 5 cc. of antigen; half of the animals received 5 cc. egg-white 30 minutes previous to the feeding of antigen. Five days later all animals were tested for immunity by intraperitoneal injection of 0.25 cc. of graded dilutions of broth culture of the homologous type of virulent pneumococcus.