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G T Chae

Publications and source records attributed to G T Chae.

6 recordsLinked to original sources
PubMed2002

Typing of clinical isolates of Mycobacterium leprae and their distribution in Korea.

Although there is no genetic diversity in isolates of Mycobacterium leprae, the variance of tandem repeats in the rpoT gene was recently demonstrated. We have typed clinical isolates of M. leprae in Korea using difference of the tandem repeats in the rpoT gene. Among 69 patients, 65 Korean isolates (94.2%) demonstrated four copies of the 6 bp tandem repeat (GACATC) in the rpoT gene, and incidences of three copies were found in only two Koreans and two foreigners (2.9%, respectively).

Base Sequence↗
PubMed2001

Detection of Toll-like receptor 2 (TLR2) mutation in the lepromatous leprosy patients.

Toll-like receptor 2 (TLR2) is critical in the immune response to mycobacterial infections and the mutations in the TLR2 have been shown to confer the susceptibility to severe infection with mycobacteria. To define this, we screened the intracellular domain of TLR2 in 131 subjects. Groups of 45 lepromatous and 41 tuberculoid leprosy (TT) patients and 45 controls were investigated. Ten subjects among the lepromatous leprosy (LL) patients had a band variant detected by single-stranded conformational polymorphism. DNA sequencing detected a C to T substitution at nucleotide 2029 from the start codon of the TLR2. The mutation would substitute Arg to Trp at amino acid residue 677, one of the conserved regions of TLR2. In our results, the mutation was involved in only LL, not TT and control. Thus, we suggest that the mutation in the intracellular domain of TLR2 has a role in susceptibility to LL.

Amino Acid Sequence↗
PubMed2000

Mycobacterium leprae typing by genomic diversity and global distribution of genotypes.

The genetic diversity and related global distribution of 51 Mycobacterium leprae isolates were studied. Isolates were obtained from leprosy patients from 12 geographically distinct regions of the world and two were obtained from nonhuman sources. Polymerase chain reaction (PCR) followed by DNA sequencing was performed targeting the rpoT gene of M. leprae. Isolates were classified into two groups based on the number of tandem repeats composed of 6 base pairs in the rpoT gene. Isolates from Japan (except Okinawa) and Korea belonged to one group, while those from Southeast Asian countries, Brazil, Haiti and Okinawa in Japan belonged to a second genotype. M. leprae obtained from two nonhuman sources (an armadillo and a mangabey monkey) revealed the latter genotype. These results demonstrate the genetic diversity of M. leprae and the related genotype-specific distribution in the world.

Bacterial Proteins↗
PubMed1999

Identification of mycobacterial species by comparative sequence analysis of the RNA polymerase gene (rpoB).

For the differentiation and identification of mycobacterial species, the rpoB gene, encoding the beta subunit of RNA polymerase, was investigated. rpoB DNAs (342 bp) were amplified from 44 reference strains of mycobacteria and clinical isolates (107 strains) by PCR. The nucleotide sequences were directly determined (306 bp) and aligned by using the multiple alignment algorithm in the MegAlign package (DNASTAR) and the MEGA program. A phylogenetic tree was constructed by the neighbor-joining method. Comparative sequence analysis of rpoB DNAs provided the basis for species differentiation within the genus Mycobacterium. Slowly and rapidly growing groups of mycobacteria were clearly separated, and each mycobacterial species was differentiated as a distinct entity in the phylogenetic tree. Pathogenic Mycobacterium kansasii was easily differentiated from nonpathogenic M. gastri; this differentiation cannot be achieved by using 16S rRNA gene (rDNA) sequences. By being grouped into species-specific clusters with low-level sequence divergence among strains of the same species, all of the clinical isolates could be easily identified. These results suggest that comparative sequence analysis of amplified rpoB DNAs can be used efficiently to identify clinical isolates of mycobacteria in parallel with traditional culture methods and as a supplement to 16S rDNA gene analysis. Furthermore, in the case of M. tuberculosis, rifampin resistance can be simultaneously determined.

Amino Acid Sequence↗
PubMedDate not supplied

Gamma interferon in experimental leprosy.

We have shown that preactivated MACs are able to cope with newly acquired leprosy bacilli, and a high intracellular burden of live M. leprae induces a refractory response of the host MAC to activation by IFN-gamma. Our studies underscore the fact that MAC function in LL is dependent on localized conditions, influenced by the high intracellular burden of leprosy bacilli and, in part, involving the production of prostanoids. These findings preclude inferences about the function of granuloma MAC s in leprosy based on the responses of MACs from other easily accessible anatomical compartments such as the peritoneal cavity or peripheral blood. We feel that the clearance of bacilli from the LL lesion as a consequence of local immunotherapeutic measures or chemotherapy likely depends on the influx of new competent MAC rather than the activation of resident lepromatous MACs.

Animals↗