Immunological Studies of Rickettsia Complement Fixation Test Using Ether Extracted Antigens from Rickettsia Orientalis

Abstract

Complement fixation tests were performed by the use of group (species)-specific soluble antigens and type (strain)-specific particle antigens obtained by ether extraction from yolk sac materials infected with Gilliam, Karp, and Kato strains of Rickettsia (R) orientalis respectively. The results were as follows:
1. In mice infected with R. orientalis, complement fixing antibodies against the both soluble and particle antigens began to appear almost at the same time on 14th to 15th day after the infection, rose rapidly thereafter, and reached almost maximum on 19th to 20th day. The titers tested on 90th and 180th day still remained higher, though below the maximum in some degree. In general, the titers obtained with particle antigens appeared to be a little higher than those with soluble antigens. On the other hand, these latter showed a tendency to decline somewhat earlier than the former in the course of infection.
2. On 32 sera obtained from 13 patients with tsutsugamushi disease (scrubtyphus), complement fixation tests were made. In all cases, an increase of complement fixing titers was demonstrated in the convalescent sera. Positive reaction against soluble antigens was shown in 8 out of 13 cases, while 11 out of 13 were shown positive against particle antigens. The titers obtained with soluble antigens from Gilliam, Karp, and Kato strains respectively were almost the same in all cases, however, those obtained with particle antigens were more or less different from each other according to strains used. This finding indicates that soluble antigens are group (species)-specific and particle antigens are type (strain)-specific, in human cases, as is the case in mice.
Those test antigens and control antigens which were obtained from non-infected yolk sac materials have shown slightly positive non-specific reaction against Wassermann positive human sera. This fact should be taken into consideration in practising specific serological diagnosis of tsutsugamushi disease using these antigens and securing the proper assessment of the results.