Antigenic Classification of Rickettsia Tsutsugamushi Isolates From Small Mammals Trapped in Developing Oil Palm Complex in Peninsular Malaysia

Abstract

SUMMARY: Fifty-one Rickettsia tsutsugamushi isolates from small mammals collected in central Peninsular Malaysia were serologically characterized by direct immunofluorescence using eight prototype strains. Karp and Karp-related (TA763, TA686, TA716) antigens were found in 90.2% of the isolates.

Serologic Analysis of Scrub Typhus Isolates From the Pescadores and Philippine Islands

“…Although isolates with multiple antigenic combinations could result from a single rickettsial strain with a mosaic of determinants, we believe the most obvious explanation is that these represent mixtures of individual strains. A similar conclusion was reached in a recent study with two Leptotrombidium species of laboratory-reared chiggers which were multiplyinfected with R. tsutsugamushi strains (Shirai et al, 1982b (Shirai et al, 1978(Shirai et al, , 1979(Shirai et al, , 1980(Shirai et al, , 1981a(Shirai et al, ,b,c, 1982a …”

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

“…Before the molecular studies initiated by the first sequencing of genes from O. tsutsugamushi [90][91][92], most antigenic characterization was done using DFA and IFA [45,102,118,119]. By far the most extensive use of DFA antigen characterization for the identification of regional variation of Orientia isolates was by Shirai et al [17,46,87,[120][121][122] working at the US Army Medical Research Unit, Institute for Medical Research, Kuala Lumpur, Malaysia, from 1978 through 1986. The microdot modification developed there allowed a more complete DFA characterization of isolates from humans [46], rodents [120], and chigger-pools obtained from mice or direct characterization of Orientia strains from dissected mites on a single slide [12,28,123].…”

“…By far the most extensive use of DFA antigen characterization for the identification of regional variation of Orientia isolates was by Shirai et al [17,46,87,[120][121][122] working at the US Army Medical Research Unit, Institute for Medical Research, Kuala Lumpur, Malaysia, from 1978 through 1986. The microdot modification developed there allowed a more complete DFA characterization of isolates from humans [46], rodents [120], and chigger-pools obtained from mice or direct characterization of Orientia strains from dissected mites on a single slide [12,28,123]. The typical Orientia DFA panel included labeled anti-Karp, -Kato, -Gilliam, -TA678, -TA686, -TA716, -TA763, and -TH1817 sera [45].…”

“…Although the colonies are somewhat artificial because of years of multiple-passage under laboratory conditions, they represent a snapshot of infected mites in the region. Results of these studies, as well as antigenic characterization of isolates from rodents by DFA [87,120] or monkey serum samples by IFA [260] from peninsular Malaysia, suggest that Karp and "Karprelated" strains (TA716, TA763, and TA686) predominate in the region.…”