| 研究実績の概要 |
To investigate the pathogenomics of Mycobacterium orygis, an emerging zoonotic tuberculosis (TB) pathogen, we conducted a comparative whole genome analysis of M. orygis isolates that we had obtained. Our findings suggest that M. orygis has developed unique pathogenic strategies that are differ from other members of M. tuberculosis complex. For instance, unlike in M. bovis, there is a different mutation pattern in the anti-Sigk of M. orygis, leading to higher production of mpt70 and mpt83 immunogenic proteins. Furthermore, polymorphisms in gyrB, mmpL6, PPE55, Rv2042c, TbD1 were identified to be M. orygis specific. These genetic characteristics offer the potential for the development of rapid diagnostic methods for the specific detection of M. orygis. We are continuing our in-depth whole genome analysis of our M. orygis isolates by carefully scruntinizing each single nucleotide polymorphisms, insertion and deletion, and genetic recombination to determine their association with M. orygis.
We have developed a fecal mycobacterial assay that uses magnetic beads to capture TB DNA, which can later be detected by the LAMP method. When we validated in a field setting in Nepal, we detected TB bacteria in two TB-seropositive elephants. We have isolated four M. tuberculosis isolates from the culture of postmortem TB-suspected lung tissue samples of four captive elephants. We have collaborated for the surveillance of zoonotic TB in Nepal. However, we were unable to detect M. orygis and other zoonotic TB bacteria from human tuberculosis suspected samples in Nepal.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
As planned, we performed whole genome analysis of Mycobacterium orygis isolates and conducted a comparative genome analysis with other members of M. tuberculosis complex. We have identified some candidate genes and genetic regions that represent unique pathogenomic features of M. orygis. In particular, we identified M. orygis specific genetic features in anit-sigk, gyrB, mmpL6, and PPE55 genes and region of difference 12. We are now employing these M. orygis specific genetic signatures to develop simple PCR or lop mediated isothermal amplification based diagnostic methods. Additionally, We isolated four M. tuberculosis isolates from captive elephants of Nepal. We have developed simple molecular detection model for the tuberculosis surveillance across the human/livestock/wildlife interface by using LAMP and PCR based diagnostic methods. Furthermore, we have established a fecal mycobacterial assay to detect tuberculosis DNA from animal fecal samples. Although this fecal assay was able to detect TB bacteria DNA, we are continuing to improve its sensitivity and specificity.
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| 今後の研究の推進方策 |
We will collect additional new whole genome sequence from other research groups and integrate them with our results for a comprehensive genomic analysis of M. orygis. Our goal tis to identify how M. orygis might have evolved from the ancestral tuberculosis organism and successfully established itself as a causative agent of tuberculosis in animals and humans. We also plan to validate our statement that M. orygis has been historically present and endemically distributed in South Asia. Additionally, we will simplify our fecal mycobacterial molecular assay and validate it by testing in Nepal. We will perform a molecular epidemiological analysis of M. tuberculosis isolates from captive elephants of Nepal. As we have not been able to isolate M. orygis from tuberculosis suspected sample from humans, we will continue our surveillance of zoonotic TB in the TB suspected people of Nepal.
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| 次年度使用額が生じた理由 |
In the upcoming fiscal year, our plan is to continue the field epidemiological surveillance of tuberculosis across the human/livestock/wildlife interface to collect additional M. orygis isolates and other M. tuberculosis complex isolates. This will help us gain a better understanding of the eco-epidemiology of M. orygis and other tuberculosis bacteria. We will perform additional whole genome analysis of M. orygis and M. tuberculosis isolates. Furthermore, we will improve and validate molecular methods for tuberculosis detection and develop a molecular model detection model for tuberculosis surveillance.
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