Construction, screening and immunogenicity of the recombinant poxvirus vaccine rVTTδTK-RBD against SARS-CoV-2 / 细胞与分子免疫学杂志

Objective To construct a recombinant poxvirus vector vaccine, rVTTδTK-RBD, and to evaluate its safety and immunogenicity. Methods The receptor-binding domain (RBD) gene was synthesized with reference to the gene sequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was inserted into the polyclonal site of the self-constructed recombinant plasmid pSTKE, to construct the recombinant poxvirus shuttle vector pSTKE-RBD. This was then transfected into BHK-21 cells pre-infected with the vaccinia virus Tiantan strain (VTT). The recombinant poxvirus rVTTδTK-RBD was successfully obtained after several rounds of fluorescence phage screening. The effect of rVTTδTK-RBD on the body mass of BALB/c mice was detected after immunizing mice by intra-nasal vaccination. The levels of specific and neutralizing antibodies produced by rVTTδTK-RBD on BALB/c mice were analyzed after immunizing mice intramuscularly. The effect of rVTTδTK-RBD on T cell subsets in BALB/c mice was detected by flow cytometry. Results Through homologous recombination, enhanced green fluorescent protein (EGFP) screening marker, and multiple rounds of fluorescent phosphorescence phage screening, a recombinant poxvirus rVTTδTK-RBD, expressing RBD with deletions in the thymidine kinase (TK) gene, was successfully obtained, which was validated by PCR. The in vivo experiments on BALB/c mice showed that rVTTδTK-RBD was highly immunogenic against SARS-CoV-2 and significantly reduced toxicity to the body compared to the parental strain VTT. Conclusion The recombinant poxvirus vaccine rVTTδTK-RBD against SARS-CoV-2 is successfully constructed and obtained, with its safety and immunogenicity confirmed through various experiments.

In situ measurements of SO2, NOx, NOy, and O3 in Beijing, China during August 2008.

The measurement of SO(2), O(3), NO, NO(2), and NO(y) mixing ratios was conducted from Jul 28, 2008 to Sep 2, 2008 at the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP, CAS) station, which is 2km southwest to the Beijing National Stadium (Bird's Nest/Olympic Stadium). Photochemical pollution was detected during the measurement on Aug 2, 2008, and the maximum hourly average [O(3)] reached 128ppbv, caused by both the local photochemical reactions and regional transportation of pollutants. The NO(x) Ozone Production Efficiency (OPE (NO(x))) values were 6.9 and 20.2 on Aug 2 and Aug 24, 2008 respectively, which were the two days with highest O(3) pollution. The OPE (NO(x)) of 6.9 on Aug 2 was within a typical range in city area, and it implied that the high O(3) could be due to local sources. While OPE (NO(x)) of 20.2 on Aug 24 was larger than the typical value in the region, but lower than that of the surrounding clean area during 2008 Beijing Olympics Closing Ceremony. It indicated that the pollution was because of regional transportation of pollutants. In addition, 60% of the extent of the Smog Production Model (SPM) data was less than 0.6 and the rest was slightly larger than 0.6, with maximum of 0.78. It indicated that the sensitivity of O(3) generated was volatile organic compounds (VOCs) control during the observation period. The SPM results also implied that O(3) product in high-O(3) day is a transition state from VOCs sensitivity to NO(x) sensitivity. Lastly, the analysis of the wind direction and extent of SPM showed that the photochemical pollution of this region was mostly subject to the influence of southeastern air flow in the summer.