Effect of Trypsin on the Virus of Trachoma. ∗

Abstract

In an attempt to separate the virus of trachoma from the mixture of tissues and material accompanying it when obtained from the eye, a number of chemical and physical means were studied without accomplishing the desired result. 1 While filtration is to a measure successful for this purpose, the method is unsatisfactory because of its low frequency of success, irregularity, and loss of virus. 2 The establishment, however, of the resistance of several viruses to the digestive action of trypsin 3 suggested a possible expedient for the liberation in this instance of the infectious agent from the epithelial cell, which in one way or another usually fixes the virus. Accordingly, the infectious tissues scraped from the conjunctiva of patients during operation of grattage were subjected to digestion by trypsin.

Conjunctival scrapings from both eyes of single patients were suspended in 1.5 cc of veal infusion broth, and the suspensions from different individuals were pooled and ground aseptically with mortar and pestle in the absence of abrasive. Equal portions were then removed, and to one was added an equal volume of trypsin prepared in the form of a 1% solution containing in addition 0.2% sodium bicarbonate. The trypsin did not alter the reaction sufficiently to affect the virus. The other portion of ground tissues was diluted similarly with veal infusion broth. Both mixtures were then incubated under different conditions, and the degree of digestion by trypsin was determined by smears prepared at varying intervals and stained by Wright's method. Because of the fragility of the virus, however, it was not (possible to modify the basic technic as much as desired. After incubation the mixtures were shaken thoroughly and inoculated in monkeys (M. rhesus) by swabbing the conjunctiva of one eye, and pricking the surface of the conjunctiva of the other eye with a charged needle and then injecting subconjunctivally 0.2 cc to 0.5 cc.