Zhaoran Zhang

Porcine rotavirus A (RVA) is one of the major etiological agents of diarrhea in piglets and constitutes a significant threat to the swine industry. A molecular epidemiological investigation was conducted on 2422 diarrhea samples from Chinese pig farms to enhance our understanding of the molecular epidemiology and evolutionary diversity of RVA. The findings revealed an average RVA positivity rate of 42% (943/2422), and the study included data from 26 provinces, primarily in the eastern, southern and southwestern regions. Genetic evolutionary analysis revealed that G9 was the predominant genotype among the G-type genotypes, accounting for 25.32% of the total. The VP4 genotypes were P[7] (36.49%) and P[23] (36.49%). The predominant genotypic combinations of RVA were G9P[23] and G9P[7]. Eleven RVA strains were obtained via MA104 cell isolation. A rat model was established to assess the pathogenicity of these strains, with three strains exhibiting high pathogenicity in the model. Specifically, the RVA Porcine CHN HUBEI 2022 (Q-1), RVA Porcine CHN SHANXI 2022 (3.14-E), and RVA Porcine CHN HUBEI 2022 (5.11-U) strains were shown to cause diarrhea in the rats and damage the intestinal villi during the proliferation phase of the infection, leading to characteristic lesions in the small intestine. These data indicate that continuous monitoring of RVA can provide essential data for the prevention and control of this virus.

Restoring colistin’s efficacy is crucial in addressing the resistance crisis of colistin. This study utilized a high-throughput screening method to identify 43 compounds from 800 FDA-approved drugs that exhibited significant antibacterial effects when combined with colistin. Among these, cinacalcet hydrochloride (CH) was selected for its potential synergistic effect with colistin against multidrug-resistant (MDR) E. coli strains, including mcr-1-positive strains. A series of experiments revealed that the combination of CH and colistin showed strong synergy, especially in mcr-1-positive strains, restoring colistin sensitivity. The combination significantly inhibited bacterial growth and reduced CFU counts more effectively than either drug alone. Additionally, CH and colistin together significantly inhibited biofilm formation and eradicated existing biofilms, as visualized through confocal microscopy. Mechanistic studies showed that the combination increased bacterial membrane permeability and disrupted membrane integrity. The treatment also elevated extracellular ATP release and ROS production, indicating oxidative stress-induced bacterial death. Safety evaluations showed that the combination did not increase toxicity in host cells. Finally, animal models further validated the combination’s efficacy. Overall, this study showed that the combination of colistin and CH significantly restored colistin sensitivity in mcr-1-positive E. coli, revealing their synergistic antibacterial mechanism involving membrane damage and oxidative stress, with promising clinical applications.

Tuberculosis and drug-resistant TB remain serious threats to global public health. It is urgent to develop novel anti-TB drugs in order to control it. In addition to redesigning and developing new anti-TB drugs, drug repurposing is also an innovative way to develop antibacterial drugs. Based on this method, we discovered SKQ-1 in the FDA-approved drug library and evaluated its anti-TB activity. In vitro, we demonstrated that SKQ-1 engaged in bactericidal activity against drug-sensitive and -resistant Mtb and confirmed the synergistic effects of SKQ1 with RIF and INH. Moreover, SKQ-1 showed a significant Mtb-killing effect in macrophages. In vivo, both the SKQ-1 treatment alone and the treatment in combination with RIF were able to significantly reduce the bacterial load and improve the survival rate of G. mellonella infected with Mtb. We performed whole-genome sequencing on screened SKQ-1-resistant strains and found that the SNP sites were concentrated in the 50S ribosomal subunit of Mtb. Furthermore, we proved that SKQ-1 can inhibit protein translation. In summary, from the perspective of drug repurposing, we discovered and determined the anti-tuberculosis effect of SKQ-1, revealed its synergistic effects with RIF and INH, and demonstrated its mechanism of action through targeting ribosomes and disrupting protein synthesis, thus making it a potential treatment option for DR-TB.

Highly virulent Streptococcus suis (S. suis) infections can cause Streptococcal toxic shock-like syndrome (STSLS) in pigs and humans, in which an excessive inflammatory response causes severe damage. Hemolysin (SLY) is a major virulence factor of S. suis serotype 2 that produces pores in the target cell membrane, leading to cytoplasmic K⁺ efflux and activation of the NLRP3 inflammasome, ultimately causing STSLS. The critical aspect of hemolysin in the pathogenesis of S. suis type 2 makes it an attractive target for the development of innovative anti-virulence drugs. Here, we use the S. suis toxin protein (SLY) as a target for virtual screening. A compound called canagliflozin, a hypoglycemic agent, was identified through screening. Canagliflozin significantly inhibits the hemolytic activity of hemolysin. The results combined with molecular dynamics simulation, surface plasmon resonance, and nano differential scanning fluorimetry show that canagliflozin inhibits the hemolytic activity of SLY by binding to SLY. In addition, canagliflozin markedly reduced the release of SC19-induced inflammatory factors at the cellular level and in mice. Importantly, the combination of canagliflozin and ampicillin had a 90% success rate in mice, significantly greater than the therapeutic effect of ampicillin. The findings suggest that canagliflozin may be a promising new drug candidate for S. suis infections.