ObjectivesTo explore the in vitro and in vivo antibacterial activity of linezolid/fosfomycin combination against vancomycin-susceptible and -resistant enterococci (VSE and VRE), and provide a theoretical basis for the treatment of VRE.MethodsThe checkerboard method and time-kill curve study were used to evaluate the efficacy of linezolid combined with fosfomycin against VSE and VRE. The transmission electron microscopy (TEM) was employed to observe the cell morphology of bacteria treated with each drug alone or in combination, which further elucidate the mechanism of action of antibiotic combination therapy. The Galleria mellonella infection model was constructed to demonstrate the in vivo efficacy of linezolid plus fosfomycin for VSE and VRE infection.ResultsThe fractional inhibitory concentration index (FICI) values of all strains suggested that linezolid showed synergy or additivity in combination with fosfomycin against five of the six strains. Time-kill experiments demonstrated that the combination of linezolid-fosfomycin at 1×MIC or 2×MIC led to higher degree of bacterial killing without regrowth for all isolates tested than each monotherapy. TEM images showed that the combination treatment damaged the bacterial cell morphology more obviously than each drug alone. In the Galleria mellonella infection model, the enhanced survival rate of the combination treatment compared with linezolid monotherapy (P<0.05) was revealed.ConclusionOur data manifested that the combination of linezolid and fosfomycin was a potential therapeutic regimen for VRE infection. The combination displayed excellent bacterial killing and inhibited amplification of fosfomycin-resistant subpopulations.

Mastitis is one of the most important diseases affecting the dairy industry in the world, and it also poses a great threat to human food safety. In this study, we explored whether selenium can inhibit the activation of the NALP3 inflammasome and NF-κB/ MAPK pathway to achieve anti-inflammatory effects. Sixty BALB/c female mice were randomly divided into three groups according to diets of different selenium concentrations (high, normal, and low). After 90 days, mice fed the same selenium concentration were randomly divided into two smaller groups, one of which was inoculated with Staphylococcus aureus and the other injected with saline as a control. Through histopathologic examination staining, western blot, qPCR, and ELISA, the results showed that with increasing selenium concentrations, the expression levels of IL-1β, TNF-α, NALP3, caspase-1, and ASC were decreased in mouse mammary tissue. Therefore, this study revealed that selenium can attenuate S. aureus mastitis by inhibiting the activation of the NALP3 inflammasome and NF-κB/MAPK pathway.

Japanese encephalitis virus (JEV) is an important zoonotic pathogen, which causes central nervous system symptoms in humans and reproductive disorders in swine. It has led to severe impacts on human health and the swine industry; however, there is no medicine available for treating yet. Therefore, vaccination is the best preventive measure for this disease. In the study, a modified mRNA vaccine expressing the prM and E proteins of the JEV P3 strain was manufactured, and a mouse model was used to assess its efficacy. The mRNA encoding prM and E proteins showed a high level of protein expression in vitro and were encapsulated into a lipid nanoparticle (LNP). Effective neutralizing antibodies and CD8+ T-lymphocytes-mediated immune responses were observed in vaccinated mice. Furthermore, the modified mRNA can protect mice from a lethal challenge with JEV and reduce neuroinflammation caused by JEV. This study provides a new option for the JE vaccine and lays a foundation for the subsequent development of a more efficient and safer JEV mRNA vaccine.

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis epidemics in Southeast Asia, affecting mostly children, with high morbidity and mortality. During the viral maturation process, prM is cleaved into M by the cellular endoprotease furin in the acidic secretory system.

25Objective: To explore the in vitro and in vivo antibacterial activity of 26 linezolid/fosfomycin combination against vancomycin-susceptible and -resistant 27 enterococci (VSE and VRE), providing theoretical basis for the treatment of VRE. 28Methods: The checkerboard method and time-kill curve study were used to evaluate 29 the synergistic effect of linezolid combined with fosfomycin against VSE and VRE. 30The transmission electron microscopy (TEM) was employed to observe the bacterial 31 cell morphology followed by each drug alone and in combination, elucidating the 32 possible result of antibiotic combination therapy. The Galleria mellonella infection 33 model was constructed to demonstrate the in vivo efficacy of linezolid plus 34 fosfomycin for VSE and VRE infection.35 Results: The fractional inhibitory concentration index (FICI) values of all strains 36 suggested that linezolid showed synergy or additivity in combination with fosfomycin 37 against five of the six strains. Time-kill experiments demonstrated that the 38 combination of linezolid-fosfomycin at 1MIC or 2MIC led to higher degree of 39 bacterial killing without regrowth for all isolates tested than each monotherapy. TEM 40 imaging showed that the combination treatment damaged the bacterial cell 41 morphology more obviously than each drug alone. In the Galleria mellonella infection 42 model, the enhanced survival rate of the combination treatment was revealed 43 compared to linezolid monotherapy (P<0.05). 44 Conclusions: Our data manifest that the combination of linezolid and fosfomycin may 45 be a possible therapeutic regimen for VRE infection. The combination displays 46 excellent bacterial killing and inhibits amplification of fosfomycin-resistant 47 subpopulations.48