Optimization and Stability Assessment of Monochamus alternatus Antimicrobial Peptide MaltAtt-1 in Komagataella phaffii GS115 for the Control of Pine Wood Nematode.

MaltAtt-1 is an antimicrobial peptide isolated from Monochamus alternatus with nematocidal activity against pine wood nematode. In this study, a eukaryotic expression system based on Komagataella phaffii GS115 was established, and its secretory expression of MaltAtt-1 was realized. The basic properties and secondary and tertiary structures of the antimicrobial peptide MaltAtt-1 were identified by bioinformatics analysis. MaltAtt-1 is a hydrophilic stable protein, mainly composed of an α-helix (Hh), ß-folds (Ee), and irregular curls (Cc). The optimal fermentation conditions for MaltAtt-1 were determined by a single-factor test and the Box-Behnken response surface method, including an induction time of 72 h, induction temperature of 30 °C, culture medium of pH 7.6, methanol volume fraction of 2.0%, and an initial glycerol concentration of 1%. The stability of MaltAtt-1 indicated its resistant to UV irradiation and repeated freezing and thawing, but the antibacterial activity decreased significantly under the influence of high temperature and a strong acid and base, and it decreased significantly to 1.1 cm and 0.83 cm at pH 2.0 and pH 10.0, respectively. The corrected mortality of B. xylophilus achieved 71.94% in 3 h at a concentration of 300 mg·L-1 MaltAtt-1 exposure. The results provide a theoretical basis for the antimicrobial peptide MaltAtt-1 to become a new green and efficient nematicide.

Calcium stress reduces the reproductive capacity and pathogenicity of the pine wood nematode (Bursaphelenchus xylophilus) by inhibiting oxidative phosphorylation reaction.

The continuous use of chemical pesticides to control nematodes could result in the developing of pesticide-resistant nematodes. Novel nucleic acid pesticides are becoming the focus of pesticide research due to their strong specificity, high efficiency, and environmental friendliness. However, the limited known biochemical targets restrict the development of target pesticides for nematodes. The calcium stress experiments on pine wood nematodes (PWN) showed that 100 mmol/L Ca2+ resulted in longitudinal depression on the PWN body wall, reduced oviposition, and increased corrected mortality. To enrich the biological targets of nematode pesticides, we further investigated the response mechanism of PWN to calcium stress at the molecular level. Differentially expressed gene analysis showed that genes involved in the oxidative phosphorylation (OXPHOS) pathway were significantly enriched. RNA interference results of 6 key genes belonging to four mitochondrial complex I (BXNDUFA2), III (BXQCR8), IV (BXCOX17), V (BXV-ATPaseB, BXV-ATPaseE, BXV-ATPaseε) in non-stressed nematodes showed reduction in PWN oviposition, population size, feeding ability, and pathogenicity. The BXNDUFA2 gene interference had the highest inhibitory impact by decreasing the oviposition from 31.00 eggs to 6.75 eggs and PWN population size from 8.27 × 103 nematodes to 1.64 × 103 nematodes, respectively. Interestingly, RNA interference of these 6 key genes in calcium-stressed nematodes also led to increased mortality and decreased oviposition of PWN. In summary, calcium stress inhibited the reproductive capacity of PWN by down-regulating key genes BXNDUFA2, BXQCR8, BXV-ATPaseB, BXV-ATPaseE, BXV-ATPaseε, and BXCOX17, thereby reducing the pathogenicity. The current results enrich the RNAi targets in PWN and provide a scientific basis for developing novel nucleic nematicides.

[Research progress in vaccines of SARS-CoV-2].

Since the outbreak of corona virus disease 2019 (COVID-19), viral strains have mutated and evolved. Vaccine research is the most direct and effective way to control COVID-19. According to different production mechanisms, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines included inactivated virus vaccine, live attenuated vaccine, mRNA vaccine, DNA vaccine, viral vector vaccine, virus-like particle vaccine and protein subunit vaccine. Among them, viral protein subunit vaccine has a wide application prospect due to its high safety and effectiveness. Viral nucleocapsid protein has high immunogenicity and low variability which could be a new direction for vaccine production. We summarized the current development of vaccine research by reviewing the current progress, vaccine safety and vaccine immune efficiency. It is hoped that the proposed possible development strategies could provide a reference for epidemic prevention work in future.

ACE2 Receptor: A Potential Pharmacological Target in COVID-19.

Studies have shown that injection of recombinant angiotensin-converting enzyme 2 (ACE2) significantly increased circulatory levels of ACE2 activity, reduced cardiac hypertrophy and fibrosis, and effectively lowered blood pressure. In addition, recombinant ACE2 ameliorated albuminuria and might contribute to renal protection. Meanwhile, potential pharmacological treatments based on ACE2 are attracting increasing attention from scientists following a growing understanding of the role of the ACE2 receptor in the pathogenesis of coronavirus disease 2019 (COVID-19). In this article, we comprehensively summarized the literature on the structure, distribution, and function of ACE2. More importantly, we draw a conclusion that ACE2 decoys such as sACE2, hrsACE2 and ACE2-derived peptides, drugs down-regulating the ACE2 or TMPRSS2 gene expression, and the application of epigenetic modifiers and Traditional Chinese Medicine might represent promising approaches for the future of COVID-19 treatment.

Update on the treatment of multisystem inflammatory syndrome in children associated with COVID-19.

In late 2019, SARS-CoV-2 was detected in China and spread worldwide. In rare cases, children who were infected with COVID-19 may develop multisystem inflammatory syndrome (MIS-C), which could have higher mortality than COVID-19 itself. Therefore, diagnosis and management are critical for treatment. Specifically, most of the initial treatment options of MIS-C choose intravenous immunoglobulin (IVIG) and steroids as the first-line treatment for patients. Moreover, antagonists of some cytokines are used as potential future therapeutics. Of note, therapeutic plasmapheresis can be used as a treatment for refractory severe MIS-C. We believe that each patient, especially those with comorbid conditions, should have individualized treatment based on both multidisciplinary consensus approach and expert opinion.

[Antitumor effect and apoptosis induction in human cancer cell lines by BRM-SJS].

BACKGROUND & OBJECTIVE: It had been observed that BRM-SJS had antitumor effect in our clinical practice. This study was designed to investigate the antitumor activity of BRM-SJS, and mechanism of its action. METHODS: In vitro antitumor experiments with MTT method, meanwhile cell morphology, flow cytometry, and agarose gel electrophoresis were performed for determining apoptosis in several tumor cell lines. RESULTS: BRM-SJS had antitumor effects on human Suzhou human glioma (SHG-44), breast carcinoma (MCF-7), and human pancreas carcinoma (PANC1) in vitro, the IC50 values of BRM-SJS were 0. 299 mg/ml, 1.853 mg/ml and 9.416 mg/ml respectively. At the 2. 5 mg of BRM-SJS on SHG-44 and MCF-7, marked morphological changes, including cell shrinkage and condensation of chromosomes, were observed with electric microscope. The increase of apoptosis in SHG-44 and MCF-7 cells treated with BRM-SJS extracts 0.625 -2.5 mg for 14 -48 h was observed by Annexin-V/PI flow cytometry analysis. Agarose gel electrophoresis of DNA from SHG-44 and MCF-7 cells treated with BRM-SJS extracts 1.25 -5 mg for 24 h or 48 h showed marked DNA Ladder pattern. CONCLUSION: Antitumor activity of BRM-SJS may be related with inducement of apoptosis of tumor cells.