Equine Encephalomyelitis in Monkeys

[摘要] Most young rhesus monkeys are susceptible to the nasally instilled viruses of Eastern and Western encephalomyelitis. Recovery was never observed in young animals after nervous symptoms had appeared but an occasional animal had a symptomless infection resulting in a high concentration of circulating antibodies.Young monkeys have succumbed to the intralingual injection of virus of Eastern encephalomyelitis. In a few trials no encephalomyelitis was produced by the intravenous or subcutaneous inoculation of massive doses of either Eastern or Western virus. Such inoculated monkeys, however, developed circulating antibodies after about two weeks. The concentration of these antibodies has been greater after intravenous than after subcutaneous injection; it has remained high for months at least. Dropping virus into the eye has not resulted in either disease or appreciable production of antibodies. Two monkeys have been fed virus by stomach tube without subsequently becoming paralyzed and within our experience no healthy animal has contracted disease after being caged with the sick and dying.Hyperimmune horse serum, given at the time of first symptoms (fever), or later, has been without beneficial influence upon the course of either Eastern or Western disease. Injected before exposure it has provided a strong passive protection against infection from nasally instilled virus. Approximately half the animals given serum within a day after infection with virus have failed to develop disease but none of these survivors has been protected from a second exposure several weeks later.Vaccination with formalinized chicken embryo-vaccine has in most instances protected monkeys from subsequent infection with nasally instilled virus. The antibody-response to Eastern vaccine is readily studied. The titer resulting from vaccination depends on the animal; it reaches its maximum within two weeks after injection and is not enhanced by subsequent intranasal exposure to virus. Though nearly all the immune animals have developed a rich supply of antibodies a few monkeys have succumbed to virus in spite of their antibodies. Multiple vaccination is desirable but a single vaccination will protect against Eastern virus given intranasally after a month. This result has been obtained with the crude commercial vaccines and with vaccines after clarification or deformalinization.

[学科分类] 生物科学（综合）