Molecular and genomic features of Mycobacterium bovis strain 1595 isolated from Korean cattle

The aim of this study was to investigate the molecular characteristics and to conduct a comparative genomic analysis of Mycobacterium (M.) bovis strain 1595 isolated from a native Korean cow. Molecular typing showed that M. bovis 1595 has spoligotype SB0140 with mycobacterial interspersed repetitive units-variable number of tandem repeats typing of 4-2-5-3-2-7-5-5-4-3-4-3-4-3, representing the most common type of M. bovis in Korea. The complete genome sequence of strain 1595 was determined by single-molecule real-time technology, which showed a genome of 4351712 bp in size with a 65.64% G + C content and 4358 protein-coding genes. Comparative genomic analysis with the genomes of Mycobacterium tuberculosis complex strains revealed that all genomes are similar in size and G + C content. Phylogenetic analysis revealed all strains were within a 0.1% average nucleotide identity value, and MUMmer analysis illustrated that all genomes showed positive collinearity with strain 1595. A sequence comparison based on BLASTP analysis showed that M. bovis AF2122/97 was the strain with the greatest number of completely matched proteins to M. bovis 1595. This genome sequence analysis will serve as a valuable reference for improving understanding of the virulence and epidemiologic traits among M. bovis isolates in Korea.

Performance of the SD Bioline TB Ag MPT64 Rapid test for quick confirmation of Mycobacterium bovis isolates from animals

Mycobacterium (M.) bovis, a bacterium in the M. tuberculosis complex, is a causative agent of bovine tuberculosis, a contagious disease of animals. Mycobacterial culture is the gold standard for diagnosing bovine tuberculosis, but this technique is laborious and time-consuming. In the present study, performance of the SD Bioline TB Ag MPT4 Rapid test, an immunochromatographic assay, was evaluated using reference bacterial strains and M. bovis field isolates collected from animals. The SD MPT64 Rapid test produced positive results for 95.5% (63/66) of the M. bovis isolates from cattle and 97.9% (46/47) of the isolates from deer. Additionally, the test had a sensitivity of 96.5% (95% CI, 91.2-99.0), specificity of 100% (95% CI, 96.7-100.0), positive predictive value of 100% (95% CI, 96.7-100.0), and negative predictive value of 92.9% (95% CI, 82.7-98.0) for M. bovis isolates. In conclusion, the SD MPT64 Rapid test is simple to use and may be useful for quickly confirming the presence of M. bovis in animals.

Prevalence of Spotted Fever Group Rickettsia from Haemaphysalis Ticks in Chungju Province

A total of 190 ticks collected from the Chungju area of Korea was examined for the presence of Spotted Fever Group(SFG) Rickettsia using a PCR assay. Twenty-five (13.2%) Haemaphysalis ticks were found positive of the groEL gene of SFG Rickettsia. The prevalence rate of R. japonica in these 25 Haemaphysalis ticks was 72% (18 out of 25 SFG Rickettsia). The prevalence rate of R. conorii and new SFG rickettsia in these 25 Haemaphysalis ticks was 4% (1 out of 25 SFG Rickettsia) and 24% (6 out of 25 SFG Rickettsia), respectively. These results suggest that R. japonica was the highest infection frequency among in Haemaphysalis ticks SFG Rickettsia, and that R. conorii and new SFG Rickettsia are also present in the Chungju area.