The rabbit as experimental animal in the study of the typhus group of viruses

Abstract

Summary 1. 1. Special conditions of experiment must be fulfilled in attempts at the transmission of viruses of the typhus group from man to susceptible animals. 2. 2. Even with the virulent virus of louse-borne typhus of East-European origin it is necessary, in order to demonstrate infection of the rabbit with some degree of regularity 1. (a) To inoculate a very large dose of the patients' blood and 2. (b) To keep the inoculated rabbits under observation for not less than six to seven weeks. This is in accord with Nicolle's earlier observations on direct transmission from man to the guineapig. 3. 3. It is suggested that the unsuccessful transmission experiments with the viruses of some of the milder forms of typhus are due to this peculiar property of typhus viruses when present in human blood. 4. 4. The use of the rabbit test is recommended for the analysis of the antigenic structure of different typhus viruses by means of serological tests with various types of B. proteus X. 5. 5. The simple test for agglutinin production in the rabbit is only capable of demonstrating the main O antigen of the virus. 6. 6. Minor antigenic differences between typhus viruses, due to overlapping group O antigens, are disclosed by the cross-immunity test in the rabbit re-stimulation of agglutinins indicates diversity, failure to re-stimulate agglutinins indicates identity in antigenic structure. 7. 7. The virus of the endemic typhus of Sao Paulo represents a serological variety of virus, which possesses a main antigen of type X19 and a group antigen of type XK.