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Comparative genomic analyses of Mycoplasma hyopneumoniae pathogenic 168 strain and its high-passaged attenuated
1Division of Animal Infectious Diseases, State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
Background:
Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia (EP), a mild, chronic pneumonia of swine. Despite presenting with low direct mortality, EP is responsible for major economic losses in the pig industry. To identify the virulence-associated determinants of M. hyopneumoniae, we determined the whole genome sequence of M. hyopneumoniae strain 168 and its attenuated high-passage strain 168-L and carried out comparative genomic analyses.
Results:
We performed the first comprehensive analysis of M. hyopneumoniae strain 168 and its attenuated strain and made a preliminary survey of coding sequences (CDSs) that may be related to virulence. The 168-L genome has a highly similar gene content and order to that of 168, but is 4,483 bp smaller because there are 60 insertions and 43 deletions in 168-L. Besides these indels, 227 single nucleotide variations (SNVs) were identified. We further investigated the variants that affected CDSs, and compared them to reported virulence determinants. Notably, almost all of the reported virulence determinants are included in these variants affected CDSs. In addition to variations previously described in mycoplasma adhesins (P97, P102, P146, P159, P216, and LppT), cell envelope proteins (P95), cell surface antigens (P36), secreted proteins and chaperone protein (DnaK), mutations in genes related to metabolism and growth may also contribute to the attenuated virulence in 168-L. Furthermore, many mutations were located in the previously described repeat motif, which may be of primary importance for virulence.
Conclusions:
We studied the virulence attenuation mechanism of M. hyopneumoniae by comparative genomic analysis of virulent strain 168 and its attenuated high-passage strain 168-L. Our findings provide a preliminary survey of CDSs that may be related to virulence. While these include reported virulence-related genes, other novel virulence determinants were also detected. This new information will form the foundation of future investigations into the pathogenesis of M. hyopneumoniae and facilitate the design of new vaccines.
Insights
Comparative genomics revealed genetic variations in Mycoplasma hyopneumoniae, identifying novel virulence determinants and providing insights into porcine enzootic pneumonia (EP) pathogenesis and vaccine development.
Area of Science:
- Veterinary Microbiology
- Genomics
- Pathogenesis
Background:
- Mycoplasma hyopneumoniae causes porcine enzootic pneumonia (EP), a significant economic concern in the swine industry.
- Understanding the genetic basis of M. hyopneumoniae virulence is crucial for disease control.
Purpose of the Study:
- To identify virulence-associated genetic determinants of M. hyopneumoniae.
- To compare the whole genome sequences of a virulent strain (168) and its attenuated high-passage derivative (168-L).
Main Methods:
- Whole genome sequencing of M. hyopneumoniae strains 168 and 168-L.
- Comparative genomic analysis, including identification of insertions, deletions, and single nucleotide variations.
- Analysis of variants affecting coding sequences (CDSs) and comparison with known virulence factors.
Main Results:
- The attenuated strain 168-L genome showed high similarity to strain 168 but was smaller due to indels and SNVs.
- Many identified variants affected CDSs, including known virulence determinants like mycoplasma adhesins, cell envelope proteins, and secreted proteins.
- Mutations in metabolism and growth-related genes, as well as in repeat motifs, were also observed and may contribute to attenuated virulence.
Conclusions:
- Comparative genomics elucidated the virulence attenuation mechanism of M. hyopneumoniae.
- The study identified both known and novel virulence-associated CDSs, offering a foundation for further research.
- Findings will aid future investigations into M. hyopneumoniae pathogenesis and the development of new vaccines.
