Propolis was widely used in health preservation and disease healing, it contains many ingredients. The previous study had been revealed that the propolis has a wide range of efficacy, such as antiviral, immune enhancement, anti-inflammatory and so on, but its antiviral components and underlying mechanism of action remain unknown. In this study, we investigated the chemical composition, and anti-PPV and immunological enhancement of Propolis Flavonoid(PF). Chemical composition of PF was distinguished by UPLC-Q/TOF-MS/MS analysis.The presence and characterized of 26 major components was distinguished in negative ionization modes.To evaluate the effects of PF used as adjuvant on the immune response porcine parvovirus (PPV). Thirty Landrace-Yorkshire hybrid sows were randomly assigned to 3 groups, and the sows in adjuvant groups were intramuscular injected PPV vaccine with 2.0 mL PF adjuvant (PA), oilemulsion adjuvant (OA), respectively. After that, serum hemagglutination inhibition antibody titers, IgM and IgG subclasses, eripheral lymphocyte proliferation activity, and concentrations of cytokines were measured. Results indicated an enhancing effect of PA on IgM, IL-2, IL-4, IFN-γ and the IgG subclass responses. These findings suggested that PA could significantly enhance the immune responses. Furthermore, we screened the chemical components the effective of anti-PPV, Ferulic acid have an excellently anti-PPV effective.

Staphylococcus aureus (S. aureus) is a major human pathogen that requires new antibiotics with unique mechanism. A new pleuromutilin derivative, 14-O-[(4,6-Diaminopyrimidine-2-yl) thioacetyl] mutilin (DPTM), has been synthesized and proved as a potent antibacterial agent using in vitro and in vivo assays. In the present study, DPTM was further in vitro evaluated against Methicillin-resistant Staphylococcus aureus (MRSA) isolated from dairy farms and outperformed tiamulin fumarate, a pleuromutilin drug used for veterinary. Moreover, a murine skin wound model caused by MRSA infection was established and the healing effect of DPTM was investigated. The results showed that DPTM could promote the healing of MRSA skin infection, reduce the bacterial burden of infected skin MRSA and decrease the secretion of IL-6 and TNF-α inflammatory cytokines in plasma. These results provided the basis for further in-depth drug targeted studies of DPTM as a novel antibacterial agent.

Under the pressure of fluoroquinolones, Pasteurella multocida (PM) can easily develop resistance to fluoroquinolones mediated by QRDR target mutation. It is imperative to find new drug resistance inhibitor targets to combat the rapid development of drug resistance. In order to overcome these problems, we sequenced the transcriptome of PM with different levels of resistance to ENR(0.03 μg/mL; 8 μg/mL; 32μg/Ml, Enrofloxacin). The results showed that with the increase of resistance to fluoroquinolones, the expression of satP gene was significantly up-regulated. The satP gene deletion strain and replenishment strain were constructed, and their drug resistance and tolerance were determined. The results showed that the deletion of satP gene did not affect the resistance of PM to fluoroquinolones, rather affected the time when PM developed resistance to fluoroquinolones. After 10 generations of drug induction, the MIC (minimum inhibitory concentration) of fluoroquinolones for wild strain was 64 μg/mL, while the MIC for satP gene deletion strain was only 8 μg/mL. The MDK99 test (time to kill 99% bacteria),agar diffusion test and mutation frequency test showed that the tolerance of satP gene deletion strain was significantly lower than that of wild strain. At the same time, the virulence of gene deletion strain and wild strain was tested, and about 400 times decreased virulence was observed for satP gene deletion strain. The mouse infection model confirmed that mice infected with satP gene deletion strains were more likely to be treated with ENR than mice infected with wild-type bovine PM strains. The results show that satP has potential to be a target of fluoroquinolone resistance inhibitors.