Spotted fever group and typhus group rickettsioses in humans, South Korea

Abstract

The presence of the nucleic acid of the spotted fever group (SPG) and typhus group (TG) rickettsiae was investigated in 200 serum specimens seropositive for SFG rickettsiae by multiplex-nested polymerase chain reaction with primers derived from the rickettsial outer membrane protein B gene. The DNA of SFG, TG, or both rickettsiae was amplified in the 24 serum specimens, and sequence analysis showed Rickettsia conorii, R. japonica, and R. felis in the specimens. R. conorii and R. typhi were found in 7 serum specimens, which indicated the possibility of dual infection in these patients. These findings suggest that several kinds of rickettsial diseases, including boutonneuse fever, rickettsialpox, R. felis infection, and Japanese spotted fever, as well as scrub typhus and murine typhus, are occurring in Korea.

Figure 1

Agarose gel electrophoresis analysis on 1.5% agarose gel of DNA sequences amplified by multiplex-nested polymerase chain reaction (PCR) assay by using outer and inner primer sets targeted rompB gene and template DNAs from serum samples. Lanes: M, size marker DNA (100-bp DNA ladder); 1–24, each number of amplified H products. The number on the left indicates the molecular size (in base pairs) of the amplified PCR products.

Figure 2

Restriction fragment length polymorphism analysis of H1 products amplified with multiplex-nested primer set from seropositive sera. Ethidium bromide–stained polyacrylamide gels of AluI restriction endonuclease digestion of ≈420 bp rickettsial DNA amplified by using the nested primer H set WJ77/80 in the primary reactions and WJ79/83/78 in the nested reactions. Lanes: M, size marker DNA (25-bp DNA ladder); 1–18: H1–H18; 19–23: H20–24; C, Rickettsia conorii; A, R. akari; J, R. japonica; F, R. felis. J–S; predicted fragments after digestion. The number on the left indicates the molecular size (in base pairs) of restriction fragments.

Figure 3

Restriction fragment length polymorphism analysis of H2-products amplified with multiplex-nested primer set from seropositive sera. Ethidium bromide–stained polyacrylamide gels of AluI restriction endonuclease digestion of ≈230-bp rickettsial DNA amplified by using the nested primer H set WJ77/80 in the primary reactions and WJ79/83/78 in the nested reactions. Lanes: M, size marker DNA (25-bp DNA ladder); 1, H3-2; 2, H7-2; 3, H8-2; 4, H13-2; 5, H14-2; 6, H15-2; 7, H18-2; 8, H19; P, Rickettsia prowazekii; T, R. typhi. P and T; predicted fragments after digestion. The number on the left indicates the molecular size (in base pairs) of restriction fragments.

Figure 4

Agarose gel electrophoresis analysis on 1.5% agarose gel of DNA sequences amplified by nested polymerase chain reaction (PCR) assay using primer sets targeted partial gltA gene and template DNA sequences from 24 serum samples. Lanes: M, size marker DNA (100-bp DNA ladder); 1–24, each number of amplified gltA products. The number on the left indicates the molecular size (in base pairs) of the amplified PCR products.