THE GROWTH OF HERPES SIMPLEX VIRUS IN ONE-DAY EGGS UNDER ANAEROBIC INCUBATION, WITH PRETREATMENT OF CHILLING OR WITH ADDITION OF CYANIDE

Abstract

The demonstration by Yoshino (1956) that the 1-day old hen's egg was capable of growing herpes simplex virus extended the usefulness of fertile hen's eggs in virology, and subsequent reports from this and other laboratories testified that the 1-day egg was one of, the most useful hosts for experimental infection of rabies (Yoshino, Kuma, Kondo and Kitaoka, 1956), vaccinia (Oya, 1956), variola (Oya, 1956), Japanese B encephalitis (Matumoto, 1957), Rift Valley fever (Matumoto, 1956), dengue (Nakagawa and Shingu, 1958) and canine distemper viruses (Kaneko and Shibuki, 1958; Fujie and Sawada, personal communication) .In the above-cited report, Yoshino (1956) described a technic by which egg-white of infected 1-day eggs was replaced with saline, stating that a considerable extent of viral release from blastodermal cells into saline was observed. Detailed studies using this technic (Yoshino and Taniguchi, 1957) indicated that this culture method could be regarded as a new type of tissue culture. One of the most interesting observations in these studies was that 1-day eggs so treated showed markedly restricted embryonic development while blastodermal cells grew almost normally on the surface of the yolk sac. This trend of independency between the embryonic and blastodermal developments was observed not only in eggs infected before egg-white replacement but also in the case of egg-white replacement of uninfected 1-day eggs.This fact seemed to imply that the embryo of the 1-day egg is vulnerable to such a mechanical treatment as egg-white replacement whereas the blastoderm surrounding it is quite resistant to the same treatment. Further evidence to support this interpretation was obtained in an experiment (Yoshino and Tani-guchi, unpublished) in which 1-day eggs were egg-white-replaced and incubated for varying periods prior to infection with herpes virus. Thereby, the blasto-dermal cells covering the yolk sac retained their virus-growing capacity for at least 4 weeks without any appreciable reduction. These results suggested that the conditions essential to embryonic development might not necessarily apply to growth of blastodermal cells, and there might possibly exist certain conditions under which the embryonic development could be suppressed while the blasto-dermal cells could multiply independently retaining virus-growing ability.Hence, search has been made for such conditions, and it was eventually found that air-tight sealing in liquid paraffin, chilling or addition of cyanide could produce the desired conditions. As a result of this study, the blastodermal cells turned out to be by far more resistant to these treatments than the embryonic cells or other known animal cells. The purpose of this report is to summarize the results of all these experiments.