Abstract
Recently intranuclear inclusions have been described by Hurst 1 in the nerve cells of animals suffering from equine encephalomyelitis. These bear a close resemblance to those occurring in Borna disease and in poliomyelitis. It becomes of interest to report the finding of inclusions in the brain of the chick embryo after inoculation of the developing egg with the virus of equine encephalomyelitis.
The procedure of inoculation of the developing chicks and membranes has been adequately described by Higbie and Howitt 2 as well as a study of the propagation and neutralization of the virus in vivo. Material obtained from this experimental work was fixed either in Zenker's fluid or in saturated corrosive sublimate containing 5% glacial acetic acid. The 2 to 5 micra sections of the membranes and embryos were stained with Giemsa or phloxine-methylene blue. Two series of sectioned embryos and membranes representing 3-hour intervals over a period of 24 hours were available for study. The New Jersey strain of virus and the California strain being represented in each of one series.
A noticeable edema of the chorio-allantoic membrane appeared in 3 to 6 hours following inoculation of the 10 to 12-day incubated egg. Normal horse serum was found to provoke a similar reaction but to less degree while physiological saline failed to produce an edema of the membranes. The swelling and gelatinous appearance of the membranes onto which the virus had previously been dropped rapidly increased and by 18 to 21 hours there was a collapse of many of the vessels and slight patchy streaking of the membranes. No definitely circumscribed areas of infection such as occur when herpes simplex is cultivated on the chorio-allantoic membrane (Dawson 3 ) are seen.
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