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Song Z, He W, Pei S, Zhao B, Cao X, Wang Y, He P, Liu D, Ma A, Ou X, Xia H, Wang S, Liu C, Zhao Y. Association of lineage 4.2.2 of Mycobacterium tuberculosis with the 63-bp deletion variant of the mpt64 gene. Microbiol Spectr 2023; 11:e0184223. [PMID: 37947405 PMCID: PMC10714870 DOI: 10.1128/spectrum.01842-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 10/03/2023] [Indexed: 11/12/2023] Open
Abstract
IMPORTANCE To date, rapid diagnostic methods based on the MPT64 antigen assay are increasingly utilized to differentiate between non-tuberculous mycobacteria and TB disease in clinical settings. Furthermore, numerous novel techniques based on the MPT64 release assay are continuously being developed and applied for the identification of both pulmonary and extrapulmonary TB. However, the diagnostic accuracy of the MPT64 antigen assay is influenced by the presence of 63 bp deletion variants within the mpt64 gene. To our knowledge, this is the first report on the association between the 63 bp deletion variant in mpt64 and Mycobacterium tuberculosis L4.2.2 globally, which highlights the need for the cautious utilization of MPT64-based testing in regions where L4.2.2 isolates are prevalent, such as China and Vietnam, and MPT64 negative results should be confirmed with another assay. In addition, further studies on vaccine development and immunology based on MPT64 should consider these isolates with 63 bp deletion variant.
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Affiliation(s)
- Zexuan Song
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Wencong He
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Shaojun Pei
- School of Public Health, Peking University, Beijing, China
| | - Bing Zhao
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiaolong Cao
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yiting Wang
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ping He
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Dongxin Liu
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Aijing Ma
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xichao Ou
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Hui Xia
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Shengfen Wang
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Chunfa Liu
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Yanlin Zhao
- National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, China
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Detection of Mycobacterium tuberculosis Complex in Sputum Samples Using Droplet Digital PCR Targeting mpt64. Pathogens 2023; 12:pathogens12020345. [PMID: 36839617 PMCID: PMC9966028 DOI: 10.3390/pathogens12020345] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Tuberculosis (TB) is one of the top 10 causes of death worldwide. It is challenging to find methods of diagnosis of active pulmonary TB that are sensitive enough to detect cases for proper treatment before unintentional transmission. Droplet digital PCR (ddPCR) is a highly sensitive method to detect genetic material of pathogens, but it has rarely been used for diagnosis of TB. This study compared the sensitivity of ddPCR with that of GeneXpert and AFB smear microscopy in 180 leftover sputum samples from patients suspected of having TB on the basis of clinical symptoms and radiography. Absolute quantification of copy numbers of MTB-specific genes was possible using ddPCR targeting the mpt64 gene. Among the 180 samples, 41.1% were diagnosed as having TB using ddPCR. The sensitivities of AFB smear microscopy, GeneXpert and ddPCR were 41.9%, 82.4% and 100%, respectively. AFB smear microscopy and GeneXpert both had a specificity of 100%, and the specificity of ddPCR was 95.3%. The accuracy of ddPCR (97.2%) is higher than that of GeneXpert (92.7%). This robust ddPCR system could potentially be used as a method for early diagnosis of TB.
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