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Published on: September 27, 2018
Intra-subspecies sequence variability of the MACPPE12 gene in Mycobacterium avium subsp. hominissuis
Tomotada Iwamoto1, Kentaro Arikawa1, Chie Nakajima2
1Department of Infectious Diseases, Kobe Institute of Health, 4-6 Minatojima-nakamachi, Chuo-ku, Kobe 650-0046, Japan.
Abstract:
The PE (Pro-Glu) and PPE (Pro-Pro-Glu) multigene families are unique to mycobacteria, and are highly expanded in the pathogenic members of this genus. We determined the intra-subspecies genetic variability of the MACPPE12 gene, which is a specific PPE gene in Mycobacterium avium subsp. hominissuis (MAH), using 334 MAH isolates obtained from different isolation sources (222 human isolates, 145 Japanese and 77 Korean; 37 bathroom isolates; and 75 pig isolates). In total, 31 single-nucleotide polymorphisms (SNPs), which consisted of 16 synonymous SNPs and 15 nonsynonymous SNPs, were determined through comparison with the MACPPE12 gene sequence of MAH strain 104 as a reference. As the result, the 334 MAH isolates were classified into 19 and 13 different sequevars at the nucleic acid level (NA types) and amino acid level (AA types), respectively. Among the 13 AA types, only one type, the AA02 type, presented various NA types (7 different types) with synonymous SNPs, whereas all other AA types had a one-to-one correspondence with the NA types. This finding suggests that AA02 is a longer discernible lineage than the other AA types. Therefore, AA02 was classified as an ancestral type of the MACPPE12 gene, whereas the other AA types were classified as modern types. The ubiquitous presence of AA02 in all of the isolation sources and all different sequevars classified by the hsp65 genotype further supports this classification. In contrast to the ancestral type, the modern types showed remarkable differences in distribution between human isolates and pig isolates, and between Japanese isolates and Korean isolates. Divergence of the MACPPE12 gene may thus be a good indicator to characterize MAH strains in certain areas and/or hosts.
Insights
Genetic analysis of the MACPPE12 gene in Mycobacterium avium subsp. hominissuis (MAH) revealed distinct ancestral and modern types. These genetic variations can help characterize MAH strains across different hosts and geographical regions.
Area of Science:
- Microbiology
- Genetics
- Mycobacterial research
Background:
- The PE (Pro-Glu) and PPE (Pro-Pro-Glu) gene families are characteristic of mycobacteria, with significant expansion in pathogenic species.
- Mycobacterium avium subsp. hominissuis (MAH) harbors specific PPE genes, including MACPPE12, whose genetic variability is crucial for understanding strain diversity.
Purpose of the Study:
- To investigate the intra-subspecies genetic variability of the MACPPE12 gene in Mycobacterium avium subsp. hominissuis (MAH).
- To classify MAH isolates based on MACPPE12 genetic variations and assess their distribution across different sources and geographical locations.
Main Methods:
- Sequencing of the MACPPE12 gene from 334 MAH isolates from human, pig, and bathroom sources across Japan and Korea.
- Analysis of single-nucleotide polymorphisms (SNPs) to determine nucleic acid (NA) and amino acid (AA) types.
- Comparison of MACPPE12 genetic types with hsp65 genotyping for further classification.
Main Results:
- 31 single-nucleotide polymorphisms (SNPs) were identified, leading to 19 NA types and 13 AA types among the MAH isolates.
- One AA type (AA02) was identified as an ancestral type, exhibiting multiple NA types and ubiquitous distribution.
- The remaining AA types were classified as modern types, showing distinct distribution patterns between human and pig isolates, and between Japanese and Korean isolates.
Conclusions:
- The MACPPE12 gene exhibits significant genetic variability within MAH, allowing for the classification of strains into ancestral and modern types.
- The divergence patterns of the MACPPE12 gene serve as a valuable indicator for characterizing MAH strains in specific geographical areas and hosts.
- Understanding MACPPE12 genetic diversity can aid in epidemiological studies and strain differentiation of Mycobacterium avium subsp. hominissuis.
