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T B Ho

Publications and source records attributed to T B Ho.

8 recordsLinked to original sources
PubMed2000

Comparison of Mycobacterium tuberculosis genomes reveals frequent deletions in a 20 kb variable region in clinical isolates.

The Mycobacterium tuberculosis complex is associated with a remarkably low level of structural gene polymorphism. As part of a search for alternative forms of genetic variation that may act as a source of biological diversity in M. tuberculosis, we have identified a region of the genome that is highly variable amongst a panel of unrelated clinical isolates. Fifteen of 24 isolates examined contained one or more copies of the M. tuberculosis-specific IS6110 insertion element within this 20 kb variable region. In nine of the isolates, including the laboratory-passaged strain H37Rv, genomic deletions were identified, resulting in loss of between two and 13 genes. In each case, deletions were associated with the presence of a copy of the IS6110 element. Absence of flanking tri- or tetra-nucleotide repeats identified homologous recombination between adjacent IS6110 elements as the most likely mechanism of the deletion events. IS6110 insertion into hot-spots within the genome of M. tuberculosis provides a mechanism for generation of genetic diversity involving a high frequency of insertions and deletions.

Carboxylic Ester Hydrolases↗
PubMed1998

Diagnosis and management of tuberculosis.

Traditional laboratory methods used in the diagnosis of Mycobacterium tuberculosis are hindered by the organism being fastidiously slow growing. This has previously meant that species identification and drug sensitivity testing could take several weeks. New molecular biological techniques, which can be applied to both clinical samples and cultured isolates, have accelerated this diagnostic process to a number of days. The molecular biological methods used to identify M. tuberculosis and allow rapid drug susceptibility testing are reviewed. Novel molecular strain typing ("fingerprinting") techniques to discriminate between different isolates are discussed. The impact of these new methods on management is also reviewed.

DNA Fingerprinting↗