The glycosyltransferase ST3GAL2 modulates virus proliferation and the inflammation response in porcine reproductive and respiratory syndrome virus infection.

ß-galactoside α-2,3-sialyltransferase 2 (ST3GAL2) is a member of the sialyltransferase family that mediates terminal modification of glycoproteins and glycolipids. ST3GAL2 has been found to play a role in obesity, aging, and malignant diseases. In this study, we cloned porcine ST3GAL2 (pST3GAL2) from porcine alveolar macrophages (PAMs), and its role in porcine reproductive and respiratory syndrome virus (PRRSV) infection was investigated by transcriptome analysis. pST3GAL2 was found to be located in the Golgi apparatus, and it was expressed at high levels in PRRSV-infected PAMs. Overexpression of pST3GAL2 resulted in a slight increase in PRRSV proliferation, and the interaction between pST3GAL2 and GP2a of PRRSV was detected by coimmunoprecipitation and confocal microscopy. The expression of pro-inflammatory cytokines (IFN-ß, IL-2, IL-6, IL-18, IL-1ß and TNF-α) was significantly inhibited in pST3GAL2-overexpressing, PRRSV-infected cells and upregulated in PRRSV-infected pST3GAL2-knockout cells, while the pattern of expression of anti-inflammatory cytokines (IL-4 and IL-10) was diametrically opposite. Our results demonstrate that the regulation of pST3GAL2 plays an important role in PRRSV proliferation and functional alterations in virus-infected cells. These results contribute to our understanding of the role of ß-galactoside α-2,3-sialyltransferase 2 in antiviral immunity.

The superposition anti-viral activity of porcine tri-subtype interferon expressed by Saccharomyces cerevisiae.

Interferon (IFN)-mediated antiviral responses are central to host defense against viral infection. Porcine viral infection has emerged as a serious hazard for the pig industry. The construction of an engineered Saccharomyces cerevisiae strain that efficiently produces porcine IFN has demonstrated several advantages. It can be easily fed to pigs, which helps in reducing antibiotic residues in pork and improve meat quality. In this study, the stable expression of several porcine IFN molecules (pIFN-α1, pIFN-ß, pIFN-λ1, pIFN-λ1-ß, pIFN-λ1-ß-α1) were determined using an engineered S. cerevisiae system. With the YeastFab assembly method, the complete transcriptional units containing promoter (GPD), secretory peptide (α-mating factor), target gene (IFN) and terminator (ADH1) were successfully constructed using the characteristics of type II restriction endonuclease, and then integrated into the chromosomes Ⅳ and XVI of ST1814 yeast host strain, respectively. The expression kinetics of recombinant pIFNs were further analyzed. Synergism in the expression level of IFN receptor, antiviral protein, and viral loading was observed in viral-cell infection model treated with different porcine IFN subtypes. The porcine reproductive and respiratory syndrome viral load and antibody titer in serum decreased significantly after oral administration of IFN expression yeast fermentation broth. These findings indicate the potential efficacy of multi-valent pIFNs expressing S. cerevisiae as a potent feed material to prevent viral infections of pigs.

Novel Antibiotic Combinations of Diverse Subclasses for Effective Suppression of Extensively Drug-Resistant Methicillin-Resistant Staphylococcus aureus (MRSA).

The emergence of multidrug-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), the chief etiological agent for a range of refractory infections, has rendered all ß-lactams ineffective against it. The treatment process is further complicated with the development of resistance to glycopeptides, primary antibiotics for treatment of MRSA. Antibiotic combination therapy with existing antimicrobial agents may provide an immediate treatment option. Minimum inhibitory concentrations (MICs) of 18 different commercially available antibiotics were determined along with their 90 possible pairwise combinations and 64 triple combinations to filter out 5 best combinations. Time-Kill kinetics of these combinations were then analyzed to find collateral bactericidal combinations which were then tested on other randomly selected MRSA isolates. Among the top 5 combinations including levofloxacin-ceftazidime; amoxicillin/clavulanic acid-tobramycin; amoxicillin/clavulanic acid-cephradine; amoxicillin/clavulanic acid-ofloxacin; and piperacillin/tazobactam-tobramycin, three combinations were found to be collaterally effective. Levofloxacin-ceftazidime acted synergistically in 80% of the tested clinical MRSA isolates. First-line ß-lactams of lower generations can be used effectively against MRSA infection when used in combination. Antibiotics other than glycopeptides may still work in combination.