Experimental Immunization of Horses with Herpes Virus.

Abstract

It is well known that various strains of herpes virus produce encephalitis in rabbits. Some investigators believe that the herpes virus is the etiologic agent in epidemic encephalitis in human beings. At present there is little evidence to support this view. The fact remains, however, that the herpes virus has been recovered from the brain tissue of several cases of epidemic encephalitis and the question naturally arises as to whether the herpes virus is related to the disease process in such cases or whether it is merely present by accident as a contaminating agent. A critical discussion of the question is contained in another publication. 1

In a previous communication 2 we have shown that rabbits may be hyperimmunized with herpes virus attenuated by fresh rabbit serum and that the serums from such rabbits are capable of producing passive immunity in healthy rabbits when injected intravenously. Attempts to immunize sheep were unsuccessful even when fresh virus was administered subcutaneously.

The possibility of immunizing horses against the herpes virus occurred to us as a possible means of throwing some light upon the true etiology of epidemic encephalitis. If the serums from such horses proved virucidal for the herpes virus in vitro and were capable of producing passive immunity in rabbits when injected intravenously, the possibility of treating cases of epidemic encephalitis would present itself. While such a therapeutic test for etiology would not be conclusive evidence it might throw some light on the question, particularly if the cases so treated were properly controlled with other cases receiving normal horse serum.