Qingyuan Xu

Smallpox is a highly contagious human disease caused by the variola virus. Although the disease was eliminated in 1979 due to its highly contagious nature and historical pathogenicity, with a mortality rate of up to 30%, this virus is an important candidate for biological weapons. Currently, vaccines are the critical measures to prevent this virus infection and spread. In this study, we designed a peptide vaccine using immunoinformatics tools, which have the potential to activate human immunity against variola virus infection efficiently. The design of peptides derives from vaccine-candidate proteins showing protective potential in vaccinia WR strains. Potential non-toxic and nonallergenic T-cell and B-cell binding and cytokine-inducing epitopes were then screened through a priority prediction using special linkers to connect B-cell epitopes and T-cell epitopes, and an appropriate adjuvant was added to the vaccine construction to enhance the immunogenicity of the peptide vaccine. The 3D structure display, docking, and free energy calculation analysis indicate that the binding affinity between the vaccine peptide and Toll-like receptor 3 is high, and the vaccine receptor complex is highly stable. Notably, the vaccine we designed is obtained from the protective protein of the vaccinia and combined with preventive measures to avoid side effects. This vaccine is highly likely to produce an effective and safe immune response against the variola virus infection in the body. IMPORTANCE: In this work, we designed a vaccine with a cluster of multiple T-cell/B-cell epitopes, which should be effective in inducing systematic immune responses against variola virus infection. Besides, this work also provides a reference in vaccine design for preventing monkeypox virus infection, which is currently prevalent.

A novel genotype of hepatitis E virus (HEV) has been discovered in ferrets and mink worldwide. However, the situation in China is unknown. Diverse HEV RNA belonging to HEV genotype C2 was detected in this study from 17.5% (18/103) of the laboratory ferrets and 1.9% (2/107) of farmed mink in China. Phylogenetic analysis showed that the ferret HEV strains clustered into three groups with known strains detected from the United States and the Netherlands. Attempted transmission of ferret HEV to two rabbits was not successful. This study confirmed that the C2 genotype of HEV is circulating in China and succeeded in infecting laboratory ferrets with this genotype of HEV. Further studies are required to determine whether the C2 genotype of HEV can infect humans.

For the development of a competitive ELISA (cELISA) to detect serum antibodies against the Mycoplasma mycoides subsp. Mycoides (Mmm) (strain PG1), the causative agent of contagious bovine pleuropneumonia (CBPP), all the proteins of this pathogen were analyzed. Then, a specific extracellular region of a transmembrane protein with the potential for diagnosis was identified. After that, a monoclonal antibody (Mab) named 3A8 was obtained using this extracellular region as an immunogen. Finally, a cELISA was established with the extracellular domain of this transmembrane protein as the coating antigen, Mab 3A8 as the competitive antibody, and HRP-labeled goat anti-mouse IgG as the enzyme-labeled antibody. This established method was used to detect the antibody dynamic regularity of goats which are artificially immunized Mmm and was also compared with a commercial ELISA kit. Further, the sera of 1011 different cattle from border provinces of China were monitored using a candidate Mab 3A8 cELISA. The detection results of known background sera used in this study indicate that a candidate diagnostic marker was successfully identified by analyzing all the coding proteins of Mmm in this research, and the cELISA established based on the Mab 3A8 against this protein can detect CBPP-positive serum with specificity and has no cross-reaction with other related epidemic disease-positive sera. In addition, we tested the sera collected from the border areas of China using the established ELISA, and no positive sample was detected. The research protocol of the CBPP cELISA established in this study is different from the traditional method, which can greatly reduce the investment of manpower and capital and save development time. We believe that this study's protocol could serve as a reference for the development of detection methods for mycoplasma and other complex pathogens. KEY POINTS: • A Mmm-specific diagnostic marker was obtained based on protein characteristics. • A cELISA was established for CBPP serum antibody detection. • The serological investigation was conducted for CBPP in the border areas of China.

Mycoplasmas are minimal but notorious bacteria that infect humans and animals. These genome-reduced organisms have evolved strategies to overcome host apoptotic defense and establish persistent infection. Here, using Mycoplasma bovis as a model, we demonstrate that mycoplasma glycine cleavage system (GCS) H protein (GcvH) targets the endoplasmic reticulum (ER) to hijack host apoptosis facilitating bacterial infection. Mechanically, GcvH interacts with the ER-resident kinase Brsk2 and stabilizes it by blocking its autophagic degradation. Brsk2 subsequently disturbs unfolded protein response (UPR) signaling, thereby inhibiting the key apoptotic molecule CHOP expression and ER-mediated intrinsic apoptotic pathway. CHOP mediates a cross-talk between ER- and mitochondria-mediated intrinsic apoptosis. The GcvH N-terminal amino acid 31-35 region is necessary for GcvH interaction with Brsk2, as well as for GcvH to exert anti-apoptotic and potentially pro-infective functions. Notably, targeting Brsk2 to dampen apoptosis may be a conserved strategy for GCS-containing mycoplasmas. Our study reveals a novel role for the conserved metabolic route protein GcvH in Mycoplasma species. It also sheds light on how genome-reduced bacteria exploit a limited number of genomic proteins to resist host cell apoptosis thereby facilitating pathogenesis.