Minghao Hu,1 Lei Fu,1 Bin Wang,1 Jian Xu,1 Shaochen Guo,1 Jiaojie Zhao,1 Yuanyuan Li,1 Xiaoyou Chen,2 Yu Lu1 1Department of Pharmacology, Beijing Key Laboratory of Drug Resistance Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing Chest Hospital, Capital Medical University, Beijing 101149, People’s Republic of China; 2Department of Tuberculosis, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing 101149, People’s Republic of ChinaCorrespondence: Yu Lu; Xiaoyou Chen Email luyu4876@hotmail.com; chenxy1998@hotmail.comPurpose: Linezolid (LZD) and pretomanid (PA-824) are promising candidates in regimens for the treatment of drug-resistant tuberculosis. However, research on LZD and PA-824 dual drug-resistant (LPDR) strains is rarely reported. This study aimed to investigate the genotypic and virulence characteristics of LPDR strains.Methods: To obtain the LPDR strains (marked as LP or PL strains), we used a two-way induction method, namely, we first induced LZD- or PA-824-resistant mutants from the parental Mycobacterium tuberculosis (MTB) strain H37Rv in vitro, then we obtained the LPDR strains from induction of LZD- or PA-824-resistant mutants. Mutations in rplC, rrl, or ddn and fgd1 were identified in all mutants. To investigate the virulence of these strains, six strains were selected as representative strains, including LZD-resistant strains, PA-824-resistant strains and LPDR strains. We performed the animal survival study as virulence of MTB can be measured as survival time of an animal after being infected.Results: We induced 38 mutant strains of LZD and PA-824 mono or dual drug resistance from H37Rv in vitro. The mutation frequency of rplC (C154R) gene in LPDR strains was 100% and 86%, respectively. In the animal survival study, animals infected with different drug-resistant strains survived significantly longer than those infected with H37Rv; animals infected with LPDR strains and PA-824-resistant strains survived similarly and both of which survived significantly shorter than those infected with LZD-resistant strains.Conclusion: Our study showed that rplC gene had a high mutation frequency in LPDR strains. The virulence of LPDR strains was similar to PA-824-resistant strains, and the virulence of the LZD-resistant strains was weaker than PA-824-resistant strains.Keywords: Mycobacterium tuberculosis, linezolid, PA-824, dual drug resistance, genotype, virulence