Agent of Lymphogranuloma Venereum in the Yolk-Sac of the Developing Chick Embryo

Abstract

In the course of chemotherapeutic studies, experiments were performed with a strain of the agent of lymphogranuloma venereum∗ in which passage-mouse brain was used as a source of virus. About one-third of all mice given intracerebrally 0.03 ml of 1:100 dilution died. The L_d50 1 was obtained with a dilution of 1:14. Because of its low mouse-virulence, which is in confirmation of the results of others, 2 , 3 an attempt was made to adapt the infective agent to the chorio-allantois of the chick embryo 4 in the hope of increased activity. Lesions appeared on this membrane, albeit irregularly. 5 Thus during 15 passages, approximately two-fifths of all eggs inoculated showed no lesions; one-fifth showed large central foci on the membrane; and in two-fifths the chorio-allantois showed few or many grey foci, 1 mm in diameter. The virus on the chorio-allantois was never lethal for the embryo. When 3rd, 4th and 5th passage membranes were tested in mice, 3 out of 4, 0 out of 4, and 1 out of 4 animals respectively died following intracerebral infection with 1:5 dilution. No mice succumbed when inoculated from the 10 subsequent passages. It appears, therefore, that during propagation in this tissue the particular strain of lymphogranuloma venereum virus either persisted there in very low titer or else suffered a further loss in its virulence for mice.

In view of these conditions, a further effort was made to procure more active infection by recourse to inoculation into the yolk-sac, a method used by Cox 6 to obtain large numbers of rickettsiae. Passages were initiated with mouse-brain material. Five, 6- or 7-day eggs were injected in the yolk-sac with a volume of 0.5 to 1 ml of suspension.