USE OF THE CHICK EMBRYO IN MAINTAINING AND RESTORING VIRULENCE OF NEISSERIA GONORRHOEAE

Walsh, Martin J. (Communicable Disease Center, Atlanta, Ga.), Bobby C. Brown, Leonard Brown, and Carl I. Pirkle . Use of the chick embryo in maintaining and restoring virulence of Neisseria gonorrhoeae . J. Bacteriol. 86: 478–481. 1963.—Data based on its capabilities of producing acute urethritis in human male volunteers showed that Neisseria gonorrhoeae rapidly decreased in virulence after repeated subculture on chocolate agar medium. Cultures of a particular strain (GCM13) in the allantoic cavity of a developing chick embryo maintained virulence after 82 successive transfers. Another strain (GCF62), after loss of virulence through repeated subculture on chocolate agar, was again able to produce infection after 15 consecutive transfers in chick embryo. Thus, chick embryo apparently had the capability not only to maintain the virulence factor but also to reconstitute virulence. It is postulated that chick embryo serves as a selective medium for the growth of virulent gonococci, permitting rapid multiplication of these organisms and suppressing growth of the nonvirulent organisms.