IMMUNOLOGICAL RELATIONSHIPS AMONG CENTRAL NERVOUS SYSTEM VIRUSES.

From observations carried out with the viruses of Russian spring-summer encephalitis, louping ill, W.E.E.

RELATIONSHIP OF THE VIRUS OF LOUPING ILL IN SHEEP AND THE VIRUS OF RUSSIAN SPRING-SUMMER ENCEPHALITIS IN MAN.

An experimental study of three strains of Russian spring-summer encephalitis virus and one of louping ill virus has yielded the following results:- 1. The sera of mice hyperimmunized to the viruses of Russian encephalitis and louping ill respectively have produced complement fixation with both antigens in almost precisely the same titer. 2.

NEUTRALIZING AND COMPLEMENT-FIXING ANTIBODY PRODUCTION AND RESISTANCE FOLLOWING VACCINATION IN EXPERIMENTAL ENCEPHALITIS INFECTIONS.

In mice vaccinated subcutaneously with different doses of virulent W.E.E.

VENEZUELAN EQUINE ENCEPHALOMYELITIS IN MAN.

A filterable agent was isolated from the blood and from washings of the upper respiratory passages of a young laboratory worker during a mild, acute, febrile illness. This agent was identified as a strain of Venezuelan equine encephalomyelitis virus. Circulating specific complement-fixing and neutralizing antibodies not present in sera withdrawn during the acute phase of illness were demonstrated in sera obtained during convalescence.

A NON-VIRULENT, SINGLE-DOSE RABIES VACCINE FOR PROPHYLACTIC IMMUNIZATION OF DOGS.

Our studies on rabies vaccines thus far have led us to the view that in order to develop and test vaccines, quantitative methods are necessary, and that such quantitative methods may be exploited to greatest advantage by using mice, preferably W-Swiss, as the test animal. Dogs, due to their variability and susceptibility to intercurrent infections when kept under experimental conditions, are useful chiefly to check whether or not a vaccine produces a high grade of immunity; they remain of limited value in testing the comparative potencies of weak vaccines. A second point is that the Pasteur strain of virus has proved as potent as any tested for the preparation of vaccines.

THE COMPLEMENT FIXATION TEST IN THE DIAGNOSIS OF VIRUS INFECTIONS OF THE CENTRAL NERVOUS SYSTEM.

A specific complement fixation test can be obtained in various central nervous system virus infections by using as antigens emulsions of infected brain tissue, freezing and thawing the brain emulsion, and then centrifuging it in an angle head centrifuge at 3500 R.P.M.

THE QUANTITY OF IRRADIATED NON-VIRULENT RABIES VIRUS REQUIRED TO IMMUNIZE MICE AND DOGS.

In the experiments described above, we found with respect to tissue culture rabies virus that 1 cc., which contains approximately 50,000 mouse intracerebral lethal doses, properly irradiated, was required to immunize a mouse; 500 cc., which contain 25,000,000 doses, were required to immunize a 20 pound beagle dog.

INFLUENCE OF AGE FACTORS ON IMMUNIZABILITY OF MICE TO RABIES VIRUS.

1. W-Swiss mice 60 or more days old are more readily immunizable against rabies virus infection than 20 day old or younger mice; this difference in immunizability with increasing age is most conspicuous when vaccination with virulent virus is followed by intracerebral test infection and least apparent when vaccination with avirulent virus is followed by intramuscular test infection. 2.

INFLUENCE OF AGE FACTORS ON SUSCEPTIBILITY OF MICE TO RABIES VIRUS.

1. 7 to 9 day old mice are more susceptible than older mice to injections of fixed or street virus by any route. 2.

A DOG TEST FOR MEASURING THE IMMUNIZING POTENCY OF ANTIRABIES VACCINES.

1. A quantitative method is described for testing the immunizing potency of antirabies vaccines in dogs. 2.