The Virus of Ilhéus Encephalitis

Abstract

Summary The virus of Ilhéus encephalitis is comparatively stable at room temperature. Its stability is increased by the addition of serum to diluents in which it is suspended. Its thermal death-point lies between 60 and 65 C. It passes with only a slight loss in titer through Seitz and Berkefeld “W” filters. White mice become infected following the introduction of virus by intracerebral, subcutaneous, intraperitoneal or intracutaneous injection, or by the introduction of virus by mouth. The infectability of mice by extraneural injection decreases with increasing age of the mouse. Encephalitis develops regardless of route of infection. Among the primates tested marmosets circulated virus for the longest period of time; among the rodents and marsupials metachirus had the longest period of circulation. Virus persists in the brain tissue of canaries following intracerebral injection but disappears rapidly from the blood stream. The susceptibility of canaries is greater than that of chickens or pigeons. Vampire bats and house bats were relatively insusceptible. This virus can be cultivated with ease in tissue culture or in developing chick embryo.