Studies on Scrub Typhus (Tsutsugamushi Disease)

Abstract

Although animals which recover from disease induced by one strain of Rickettsia tsutsugamushi are resistant to infection with heterologous strains (1-10), all organisms now grouped in this subgenus are not antigenically homogeneous. Evidence for heterogeneity is obtained in serological studies which employ complement fixation (11, 12), serum protection (13), and toxin-antitoxin techniques (14). Non-infectious vaccines of several types are capable of immunizing mice against the homologous strain of R. tsutsugamushi (15)(16)(17) but the degree of protection elicited by such materials against heterologous strains is unknown. The present report supplies information on this point and provides additional evidence of antigenic differences among the members of the scrub typhus group of agents. Materials and MethodsStrains ofR. tsutsugamushi.--The eight strains of R. tsutsugamushi employed in the current investigation were selected to represent the agent as obtained from various geographical areas and from different zoological sources; i.e., men, mites, and rats. The origin and lineal descent of these strains are given in some detail in the following paragraphs since it appears desirable to establish these points clearly. Certain of the immunological and serological data which indicate the known relationships of the eight to each other, or to additional strains of R.

Scrub Typhus: The Geographic Distribution of Phenotypic and Genotypic Variants ofOrientia tsutsugamushi

“…In cross-vaccination or cross-immunization, mice or guinea pigs are immunized with either killed Orientia organisms or live organisms administered by a nonlethal route of inoculation, usually subcutaneously [40,79,111,112]. Immunized animals are subsequently challenged with dilutions of live homologous or heterologous strains.…”

“…One important product of the research from the World War II era was the discovery of dramatic antigenic variation among strains of O. tsutsugamushi. This variation was shown using several methods available at the time, including cross-neutralization, cross-vaccination, or cross-immunization and complement fixation (CF) [40]. In addition to antigenic variation, research showed great interstrain variability in virulence in humans and rodents that ranged from unapparent disease to disease that was consistently fatal when untreated.…”

Antigenic Analysis by Direct Immunofluorescence of 114 Isolates of Rickettsia Tsutsugamushi Recovered From Febrile Patients in Rural Malaysia

“…Antigenic heterogeneity among strains of Rickettsia tsutsugamushi has been documented by the use of various techniques: (1) complement fixation (Bengtson, 1945(Bengtson, , 1946Shishido, 1964;Shirai and Wisseman , 1975); (2) cross-neutralization (Bell, Bennett and Whitman, 1946;Gauld , 1947, 1949;Fox, 1949;Miesse, Diercks and Danauskus, 1950;Plotnikova and Tarasevich , 1967); (3) toxin neutralization (Smadel et al, 1946); (4) cross-vaccination (Rights , Smadel and Jackson, 1948); and (5) immunofluorescence (Iida , Kawashima and Kawamura, 1965;Shirai and Wisseman, 1975).…”

Analysis of the Cross-Reactivity of Various 56 kDa Recombinant Protein Antigens with Serum Samples Collected after Orientia tsutsugamushi Infection by ELISA

“…[15][16][17][18] Homologous protection developed from natural infection persists for at least one year, but heterologous protection may remain for less than six months. 19,20 Both humoral and cell-mediated immune responses are important in protective immunity against scrub typhus.…”