Genome-wide DNA methylation pattern in a mouse model reveals two novel genes associated with Staphylococcus aureus mastitis.

OBJECTIVE

Staphylococcus aureus (S. aureus) is one of the major microorganisms responsible for subclinical mastitis in dairy cattle. The present study was designed with the aim to explore the DNA methylation patterns using the Fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) techniques in a S. aureus-infected mouse model.

METHODS

A total of 12 out-bred ICR female mice ranging from 12 -13 weeks-old were selected to construct a mastitis model. F-MSAP analysis was carried out to detect fluctuations of DNA methylation between control group and S. aureus mastitis group.

RESULTS

Visible changes were observed in white cell counts in milk, percentage of granulocytes (GRN %), percentage of lymphocytes (LYM %), CD4+/ CD8+ ratio (CD4+/ CD8+), and histopathology of mice pre and post-challenge with S. aureus. These findings showed the uniformity and suitability of the S. aureus-infected mouse model. A total of 369 fragments was amplified from udder tissue samples from the two groups (S. aureus-infected mastitis group and control group) using eight pairs of selective primers. Results indicated that the methylation level of mastitis mouse group was higher than that in the healthy group. In addition, NCK-associated protein 5 (Nckap5) and transposon MTD were identified to be differentially methylated through secondary PCR and sequencing in the mastitis group. These outcomes might play an important role in the development of S. aureus mastitis.

CONCLUSION

Collectively, our study suggested that the methylation modification in Nckap5 and transposon MTD might be considered as epigenetic markers in resistance to S. aureus-infected mastitis and provided a new insight into S. aureus mastitis research in dairy industry and public health.