Development of an indirect enzyme-linked immunosorbent assay for the detection of novel chicken orthoreovirus

A novel avian orthoreovirus (N-ARV) variant characterized with obvious arthritis and synovial inflammation, was isolated from Shandong, China in May 2016. It caused chicken poor growth and enormous economic losses to the poultry industry of China. However, there are few effective methods for detecting the antibody levels of N-ARV. In this study, a viral structural protein σC was expressed using the prokaryotic expression vector pET32a (+). The target protein was obtained by inducing for 6 hours at an IPTG concentration of 0.6mM. The optimal dilution of the coating antigen and serum antibody were determined to be 1000 fold and 10 fold respectively. A specificity test showed that there was no positive reactivity between N-ARV and other pathogens, and when the positive serum was diluted 100 times detection results were still checkable. The repeatability of this method was determined by the inter assay and intra assay tests with variability ranging from 4.85% to 7.93%. In conclusion, this indirect enzyme linked immunosorbent assay (ELISA) will be useful for large-scale serological surveys and monitoring antibody levels in N-ARV infection.

[Changes in the structure of intestinal mucosal flora in colorectal cancer patients]

OBJECTIVE

To investigate the changes in bacterial flora in fecal samples, at the tumor loci and in adjacent mucosa in patients with colorectal cancer (CRC).

METHODS

We collected fecal samples from 13 patients with CRC and 20 healthy individuals and tumor and adjacent mucosa samples from 6 CRC patients. The differences in bacterial composition between the fecal and mucosa samples were analyzed with 16S rDNA sequencing and bioinformatics methods. We also detected the total number of bacteria in the feces using flow cytometry, isolated and identified the microorganisms in the fecal and mucosa samples using common bacterial culture media. We further tested the effects of 7 isolated bacterial strains on apoptosis of 3 CRC cell lines using lactate dehydrogenase detection kit.

RESULTS

The bacterial α-diversity in the feces of healthy individuals and in adjacent mucosa of CRC patients was significantly higher than that in the feces and tumor mucosa in CRC patients (P < 0.05). Lactobacillaceae is a specific bacteria in the feces, while Escherichia, Enterococcus, and Fusobacterium are specific bacteria in tumor mucosa of CRC patients as compared with healthy individuals. Cell experiment with3 CRC cell lines showed that Bacteroides fragilis isolated from the tumor mucosa of CRC patients produced significant inhibitory effects on cell proliferation (P < 0.0001), while the isolated strain Fusobacterium nucleatum obviously promoted the proliferation of the cell lines (P < 0.001).

CONCLUSION

The bacterial flora in the feces, tumor mucosa and adjacent mucosa of CRC patients is significantly different from that in the feces of healthy individuals, and the fecal flora of CRC patients can not represent the specific flora of the tumor mucosa. Inhibition of F. nucleatum colonization in the tumor mucosa and promoting B. fragilis colonization may prove beneficial for CRC treatment.

Biomimetic Diels-Alder Reactions in Natural Product Synthesis: A Personal Retrospect

Nature has been recognized for her super capability of constructing complex molecules with remarkable efficiency and elegancy. Among nature’s versatile synthetic toolkits, Diels-Alder reaction is particularly attractive since it allows for rapid generation of molecular complexity from simple precursors. For natural products biosynthetically formed through Diels-Alder reactions, the most straightforward way to access them should build on biomimetic Diels-Alder reactions. However, the implementation of biomimetic Diels-Alder reactions in a laboratory setting may encounter considerable challenges, particularly for those suffering from complicated reactivity and selectivity issues. Indeed, the translation of a biosynthetic hypothesis into a real biomimetic synthesis entails the orchestrated combination of nature’s inspiration and chemist’s rational design. In this account, we will briefly summarize our recent progress on the application of biomimetic Diels-Alder reactions in natural product synthesis. As shown in the discussed stories, rational manipulation of the structures of biosynthetic precursors plays a crucial role for the successful implementation of biomimetic Diels-Alder reactions. 1 Introduction 2 Biomimetic Synthesis of Rossinone B 3 Biomimetic Synthesis of Homodimericin A 4 Biomimetic Synthesis of Polycyclic and Dimeric Xanthanolides 5 Biomimetic Synthesis of Periconiasins and Pericoannosins 6 Biomimetic Synthesis of Merocyctochalasans 7 Conclusion and outlook

Investigate Natural Product Indolmycin and the Synthetically Improved Analogue Toward Antimycobacterial Agents

Indolmycin (IND) is a microbial natural product that selectively inhibits bacterial tryptophanyl-tRNA synthetase (TrpRS). The tryptophan biosynthesis pathway was recently shown to be an important target for developing new antibacterial agents against Mycobacterium tuberculosis (Mtb). We investigated the antibacterial activity of IND against several mycobacterial model strains. A TrpRS biochemical assay was developed to analyze a library of synthetic IND analogues. The 4″-methylated IND compound, Y-13, showed improved anti-Mtb activity with a minimum inhibitory concentration (MIC) of 1.88 μM (∼0.5 μg/mL). The MIC increased significantly when overexpression of TrpRS was induced in the genetically engineered surrogate M. bovis BCG. The cocrystal structure of Mtb TrpRS complexed with IND and ATP has revealed that the amino acid pocket is in a state between the open form of apo protein and the closed complex with the reaction intermediate. In whole-cell-based experiments, we studied the combination effect of Y-13 paired with different antibacterial agents. We evaluated the killing kinetics, the frequency of resistance to INDs, and the mode of resistance of IND-resistant mycobacteria by genome sequencing. The synergistic interaction of Y-13 with the TrpE allosteric inhibitor, indole propionic acid, suggests that prospective IND analogues could shut down tryptophan biosynthesis and protein biosynthesis in pathogens, leading to a new class of antibiotics. Finally, we discuss a strategy to expand the genome mining of antibiotic-producing microbes specifically for antimycobacterial development.

Elucidating the selectivity of dyotropic rearrangements of β-lactones: a computational survey

A comprehensive computational study on dyotropic rearrangements of β-lactones has been performed for the first time, which provides a valuable guidance for predicting and controlling the selectivity of the reactions.

A mathematical model of COVID-19 transmission

Disease transmission is studied through disciplines like epidemiology, applied mathematics, and statistics. Mathematical simulation models for transmission have implications in solving public and personal health challenges. The SIR model uses a compartmental approach including dynamic and nonlinear behavior of transmission through three factors: susceptible, infected, and removed (recovered and deceased) individuals. Using the Lambert W Function, we propose a framework to study solutions of the SIR model. This demonstrates the applications of COVID-19 transmission data to model the spread of a real-world disease. Different models of disease including the SIR, SIRmp and SEIRρqr model are compared with respect to their ability to predict disease spread. Physical distancing impacts and personal protection equipment use are discussed with relevance to the COVID-19 spread.

Unified Biomimetic Approach to (+)-Hippolachnin A: In-Depth Insights into Its Biosynthetic Origin

A formal biomimetic synthesis of (+)-hippolachnin A has been achieved under the guidance of its plausible biosynthetic pathway. Pivotal transformations include an intriguing ¹O₂-mediated [4 + 2] cycloaddition and a tandem Kornblum-DeLaMare rearrangement/hemiketalization/dehydration reaction. The current work not only offers a unified approach to access skeletally diverse plakortin-type polyketides but also provides convincing evidence to elucidate their underlying biosynthetic network.

The expression profile of miR-222b-5p/MAPK10 in spleens of SPF chickens infected with REV-SNV at 28-42 dpi

Reticuloendotheliosis virus (REV) is an avian oncogenic retrovirus that causes atrophy of immune organs, such as the spleen, thymus, and bursa of Fabricius, leading to severe immunosuppression. However, there is limited information describing the genes or microRNAs (miRNAs) that play a role in replicating REV-spleen necrosis virus (SNV). Our previous miRNA and RNA sequencing data showed that the expression of gga-miR-222b-5p was significantly upregulated in REV-SNV-infected chicken spleens of 7, 14, and 21 dpi compared to non-infected chicken spleens, but mitogen-activated protein kinase 10 (MAPK10), which is related to innate immunity, had the opposite expression pattern. To understand chicken cellular miRNA function in the virus-host interactions during REV infection, we used quantitative reverse transcription PCR (qRT-PCR) to determine whether the expression of gga-miR-222b-5p and MAPK10 in the spleen of specific-pathogen-free chickens at 28, 35, and 42 dpi was consistent with the first 3 time points, and dual-luciferase reporter assay was used to determine the targeting relationship between gga-miR-222b-5p and MAPK10. Results show that MAPK10 was downregulated at all 3 time points; however, significant difference (p⟨0.01) was noted only at 35 dpi. Moreover, the expression of gga-miR-222b-5p was upregulated; however, significant difference (p⟨0.01) was observed only at 28 and 35 dpi. A dual-luciferase reporter assay showed that MAPK10 is a direct target of gga-miR-222b-5p. This study suggests that gga-miR-222b-5p may target MAPK10 to promote the REV-SNV-induced tumorigenesis via the RLRs signaling pathway.