Transcriptome sequencing analysis of bovine mammary epithelial cells induced by lipopolysaccharide

Mastitis in cows is caused by the inflammation of the mammary glands due to an infection by external pathogenic bacteria. Mammary gland epithelial cells, which are in direct contact with the external environment, are responsible for the first line of defense of the mammary gland against pathogenic bacteria, playing an essential role in immune defense. To investigate the mechanism of bovine mammary epithelial cells in the inflammatory process, we treated the cells with LPS for 12 hours and analyzed the changes in mRNA by transcriptome sequencing. The results showed that compared to the control group, the LPS treatment group had 121 up-regulated genes and 18 down-regulated genes. GO and KEGG enrichment analysis revealed that these differential genes were mainly enriched in the IL-17 signaling pathway, Legionellosis, Cytokine-cytokine receptor interaction, NF-kappa B signaling pathway, and other signaling pathways. Furthermore, the expression of GRO1 and CXCL3 mRNAs increased significantly after LPS treatment. These findings provide new insights for the treatment of mastitis in cows in the future.

High-throughput analysis of lncRNA in cows with naturally infected Staphylococcus aureus mammary gland

LncRNA (long non-coding RNA) is an RNA molecule with a length between 200 and 100,000 nt. It does not encode proteins and is involved in a variety of intracellular processes, becoming a research hotspot of genetics. To identify key lncRNAs associated with dairy mastitis, we collected mammary epithelial tissue samples of Normal disease-free Holstein cows (HCN) and unhealthy Holstein cows with Staphylococcus aureus (HCU) and performed RNA sequencing (RNA-seq) on the samples. A total of 270 differentially expressed lncRNAs and 500 differentially expressed mRNAs were identified by high-throughput sequencing and bioinformatics analysis. Furthermore, Hydrolase activity is the most enriched in GO, and ErbB signaling pathway is significantly enriched in KEGG. In addition, through qPCR validation of 5 candidate lncRNAs in HCN and HCU, four differentially expressed lncRNAs MSTRG.498, MSTRG57.1, MSTRG.41.1 and MSTRG 124.1 were confirmed to have significant differentially expressed in cow mastitis. Also, lncRNA MSTRG.498 and its target gene, SMC4, might directly or indirectly play a role in cow mastitis. The regulatory network of lncRNA-miRNA-mRNA has been inferred from a bioinformatics perspective, which may assist understand the underlying molecular mechanism of lncRNAs involved in regulating mastitis in cows. Our findings will provide meaningful resources for further research on the regulatory function of lncRNAs in cow mastitis.

Antibacterial effect of synthetic ultra-short lipopeptide on Streptococcus agalactiae and its active on bacterial mastitis in mice

Streptococcus agalactiae mastitis is one of the significant threats to the milk industry. The traditional antibiotic treatment method is easy to cause the emergence of resistant strains, and the problem of drug residue is increasingly severe. In this study, we designed and synthesized five lipopeptides. The antibacterial activity of different molecular structure lipopeptides against Streptococcus agalactiae was detected. Furthermore, the mouse mastitis model was established using Streptococcus agalactiae. The lipopeptides with better antibacterial effect were selected for the treatment experiment to evaluate the application value in the treatment of mastitis. The results showed that 4 of the synthesized lipopeptides had specific antibacterial activity. SLP3 and SLP4 have an excellent antibacterial effect and can treat murine mastitis caused by Streptococcus agalactiae infection within the safe concentration range. The results of this study can provide an excellent experimental basis for new antibiotics and clinical application in the treatment of dairy cow mastitis.

Evaluation of the immunogenicity of an omp A and staphylococcal target of RNAIII activating fusion protein displayed on the surface of Escherichia coli

The purpose of this investigation was to construct a recombinant Escherichia coli strain displaying the Staphylococcus aureus target of RNAIII activating protein (TRAP) on its surface, and to investigate the strain for its immunogenicity. The lpp'ompA and lpp'ompA-TRAP genes were fused by the overlap polymerase chain reaction and then ligated into expression plasmid pQE30 producing pLO and pLO-TRAP. These two recombinant plasmids were transformed into E. coli XL1-Blue, resulting in XL1-Blue/pLO and XL1-Blue/pLO-TRAP, which were induced to express protein. The expressed TRAP protein was displayed on the surface of XL1-Blue as judged by whole cell ELISA, flow cytometric analysis, and laser scanning confocal microscopy using the lpp'ompA surface display system. ICR mice were intramuscularly immunized with recombinant strains XL1-Blue/pLO and XL1-Blue/pLO-TRAP as well as recombinant protein TRAP. Immunized mice were assessed for anti-TRAP antibody and lymphocytes for secreted IL-4 and IFN-γ by ELISPOT and secreted IL-17A by indirect ELISA. Immunized mice were challenged with S. aureus Newman and HLJ23-1 strains. The results showed both XL1-Blue/pLO-TRAP and TRAP protein immunized mice to produce better cellular and humoral immunity than XL1-Blue/pLO and PBS injected mice.

First Report in China on the Identification and Drug Sensitivity of Mycobacterium elephantis Isolated from the Milk of a Cow with Mastitis

OBJECTIVE

In this study, milk from a cow with mastitis was analyzed to determine the presence of mycobacterial infection. Milk quality and security problems pertaining to the safe consumption of dairy products were also discussed in this study.

METHODS

Milk was preprocessed with 4% NaOH. Then, mycobacteria were isolated from the milk sample on L-J medium. The isolate was identified using multiple loci Polymerase Chain Reaction (PCR) and multi-locus sequence analysis with 16S rRNA, sodA, hsp65, and ITS genes. The drug sensitivity of the isolate to 27 antibiotics was tested through alamar blue assay.

RESULTS

Smooth, moist, pale yellow colonies appeared on the L-J medium within a week after inoculation. Based on the results of multiple loci PCR analysis, the isolate was preliminarily identified as non-tuberculous mycobacteria. The 16S rRNA, SodA, hsp65, and ITS gene sequences of the isolate exhibited 99%, 99%, 99%, and 100% similarities, respectively, with those of the published reference strains of Mycobacterium elephantis (M. elephantis). The drug sensitivity results showed that the strain is resistant to isoniazid, p-aminosalicylic acid, and trimesulf but is sensitive to ofloxacin, rifampicin, amikacin, capreomycin, moxifloxacin, kanamycin, levofloxacin, cycloserine, ethambutol, streptomycin, tobramycin, rifabutin, ciprofloxacin, linezolid, cefoxitin, clarithromycin, and minocycline.

CONCLUSION

To the best of our knowledge, this study is initially to report the isolation of M. elephantis from the milk of a cow with mastitis in China.