Objective:To analyze the genetic stability of two recombinant rotaviruses (rLLR/NSP3 NLuc) and (rLLR/NSP3 CoV2/RBD) that are inserted and express exogenous genes for continuous passage and proliferation on MA104 cells.Methods:After measuring the titers of two recombinant rotavirus strains, they were transferred to the P2 generation according to MOI0.01. Subsequently, the previous generation of virus lysate was diluted and activated at 1∶100, and MA104 cells were continuously infected for 18 generations (P20). The virus titers of the P1, P5, P10, P15, and P20 generation of cell lysate were measured using indirect immunofluorescence, and RT-PCR identification and dsRNA PAGE silver staining were performed. The luciferase activity of rLLR/NSP3-NLUc was also detected.Results:No inserted fragment loss was found in the recombinant rotavirus rLLR/NSP3 NLuc within 20 generations, with recombinant virus titers ranging from 3.85~5.16 × 10 6 FFU/ml, with strong luciferase signals in each generation. The recombinant rotavirus rLLR/NSP3 CoV2/RBD showed loss of inserted fragments in the 6th generation, with infectivity titers ranging from 2.6 to 3.36 in the first 5 generations of the recombinant virus × 10 6 FFU/ml. Conclusions:The recombinant rotavirus with 582 bp NLuc inserted at the end of the NSP3 gene has good genetic stability, while the recombinant rotavirus with 885 bp RBD inserted at the end of the NSP3 gene was only stable in the first 5 generations, indicating that foreign genes can be inserted at the end of the NSP3 gene of the recombinant rotavirus, and the insert can express, but its stability requires more in-depth research.

Objective:To analyze the epidemiological characteristics of norovirus (NoV) acute gastroenteritis (AGE) outbreaks caused by GII.17[P17] variant in China, 2022.Methods:Information and specimens of AGE outbreaks between January and December 2022 were collected. NoV RNA was detected in all specimens by real-time RT-PCR. The viral genome of the positive specimens were amplified, sequenced and analyzed.Results:Between January and December 2022, 360 AGE outbreaks were reported cumulatively, of which 266 outbreaks successfully obtained genotype results. GII.17 [P17] was one of the main genotypes and detected in 34 outbreaks (12.78%, 34/266), with the highest number of outbreaks detected in spring (6 outbreaks in March and 7 outbreaks in May), mainly in childcare facilities and primary schools (61.76%, 21/34). According to the result of NoV genotype analysis in different age groups, 14 strains of GII.17 [P17] in this study belonged to Cluster III b and SC III branch of Cluster III (Kawasaki308) in the capsid region and polymerase region, respectively, and both belonged to the same cluster as the variant strain (GZ41621 strain) that caused the NoV AGE outbreaks in China during the 2014/15 season. Compared to reference strains of Cluster I, Cluster II and Cluster III a, Cluster III b was provided with 22 amino acid mutations in VP1. The main amino acid changes in the subgroup of Cluster III b including the virus strains isolated in this study were at T294I and Q299R of antigen epitope A, an insertion mutation occurred at antigen epitope D, H353Q at the site I of the human histo-blood group antigen receptor binding site. The selection pressure analysis detected a large number of negative selection sites, indicating that negative selection plays an important role in the evolution of VP1 genes.Conclusions:GII.17 [P17] was one of the primary genotypes responsible for NoV diarrhea outbreaks in China in 2022. Phylogenetic analysis had revealed that it still belonged to the same cluster as the novel GII.17 [P17] variant (strain GZ41621) that caused NoV epidemics in China during the 2014/15 season, exhibiting minor amino acid variations at the potential epitope.

Objective:To increase secretory expression of SARS-CoV-2 S-EABR protein in 293T cell line by optimizing promoter, PolyA signals, signal peptide and terminal amino acids of intracellular sequences.Methods:First, four PCDNA3.1 (-) eukaryotic vector plasmids (Mb, MS, Ab, AS) containing different combinations of elements (promoter and PolyA signals) were constructed, and the S-EABR-1 target sequence optimized according to human codons was inserted. 293T-cells were transiently transfected. After 48 hours, cell culture supernatants and cell lysates were collected, and the expression level of S protein in supernatant was detected by Western blotting and ELISA. Then, the vector with the best expression element combination was selected, and the target sequences of S-EABR-1 and S-EABR-2 (4 amino acids-HSLP were added to the tail of S-EABR-1) were inserted to compare the expression level of S protein in the supernatant. Finally, based on the combination of the above elements with the best expression effect and the insertion of the target sequence, five vector plasmids (tPA, AZ, IFNα2, HSA, GLUC) were constructed to replace the original signal peptide of SARS-CoV-2 S protein, and the expression level of S protein in the supernatant was compared. At the same time, a computer was used to simulate the molecular docking of the SRP54 subunit and the signal peptide nucleic acid sequence, and the Docking Score was used as the docking evaluation criterion to predict the binding of the two.Results:In 293T cells, the Ab combination vector secreted the highest level of S-EABR, and the yield increased by 125% compared with Mb. Based on the Ab combination vector, the level of S-EABR-2 sequence expression and secretion of S-EABR increased by about 50% compared with S-EABR-1. After further replacement with the HSA signal peptide, the level of S-EABR expression and secretion increased by about 83% compared with the original signal peptide of the S protein. In addition, computer simulation result showed that the docking score between HSA and SRP54 subunit was the highest, at 1 505.861.Conclusions:The secretory expression of codon-optimized S-EABR in 293T cells can be further improved by optimizing eukaryotic expression elements (promoter, terminator and signal peptide) and intracellular sequences. The calculated simulated docking score of the affinity between the signal peptide and the SRP54 subunit is basically consistent with the secreted expression level of S-EABR also provides a design idea and screening strategy for subsequent screening of signal peptides to improve the secreted expression of the target gene.

Objective:A recombinant adenoviral vector vaccine based on non-replicating human adenovirus type 5 (Ad5), encoding the conserved domain of respiratory syncytial virus G protein (RSV-G) was constructed. The immunogenicity and protective efficacy of this vaccine were subsequently evaluated in mice.Methods:The recombinant Ad5 vector plasmid (Ad5-Gbcc-Gacc) was constructed by inserted conserved domains of RSV A and RSV B. The recombinant adenovirus Ad5-Gbcc-Gacc was rescued in HEK293A cells. The genome of virus Ad5-Gbcc-Gacc was identified by multi-enzyme digestion, and the expression of Ad5-Gbcc-Gacc was verified by Western blot. Recombinant adenovirus was used to immunize BALB/c mice via intramuscular injection with signal dose, and then challenged with RSV Long strain at week 6. The levels of G specific IgG and antibody subtypes in serum were detected by enzyme-linked immunosorbent assay, the level of neutralizing antibodies was determined by micro-neutralization assay. After challenge, the mice′s weight was recorded daily, the copies of RSV virus in the lung and nasal tissues were detected. Pathological changes in lung tissue were also examined.Results:Western blot and multi-enzyme digestion identification confirmed the successful rescue of the recombinant adenovirus. Ad5-Gbcc-Gacc elicit high titers of specific IgG, robust neutralizing antibodies, and a balanced Th1/Th2 immune response in mice. In comparison to unimmunized controls, mice immunized with Ad5-Gbcc-Gacc reduced the viral copies in both lung and nasal tissue, and exhibited only minimal pathological damage of lung tissue following RSV challenge. In conclusion, Ad5-Gbcc-Gacc induced robust immunogenicity and offers protective effects against RSV infection in murine models.Conclusions:Ad5-Gbcc-Gacc induce robust immunogenicity and can protect mice from RSV challenge, which lays a foundation for further development of RSV vaccine based on G protein.

After the first infection with varicella-zoster virus causes chickenpox and recovers, it will lurk in the spinal ganglia and other parts of the body. As people age and immunity declines, the virus reactivates and causes neurotropic bands of blisters that mainly affect the skin of the waist and chest, known as herpes zoster. At present, there is no specific drug that can prevent and control the infection and recurrence of varicella-zoster virus infection. In view of the unique immunogenic advantages of varicella-zoster virus glycoprotein E (gE), it has become an important target antigen for the development of herpes zoster vaccine at home and abroad. This article reviews the current research progress of new gE-based herpes zoster vaccine in the world, hoping to provide reference for the research and development of a new generation of herpes zoster vaccine in China.

Development of a vaccine that can simultaneously induce effective mucosal immunity and systemic immunity is an ideal goal to prevent mucosal pathogenic infections. The digestive tract has many sites for inducing mucosal immunity, including the mouth, stomach and small intestine. An ideal oral viral vaccine can not only induce better local and distal mucosal immunity, but also produce better systemic immunity. The oral viral vaccine has also attracted much attention because of its painless vaccination, self-administration and other advantages. Due to the complexity of human digestive tract environment and mucosal immunity, only three oral attenuated live vaccines have been successfully marketed for human use. This review summarizes the characteristics of gastrointestinal mucosal immunity, the current types and research status of oral viral vaccines, and the challenges faced by oral viral vaccines, with the hope to facilitate the research and development of oral viral vaccines for human use in China.
Humans ; Viral Vaccines ; Vaccination ; Immunity, Mucosal ; Vaccines, Attenuated ; Vaccine Development

Objective:To express prokaryotically GII.4 human norovirus (HuNoV) VP2 protein and to prepare polyclonal antibody against VP2.Methods:Design specific primers to amplify the VP2 gene of GII.4 HuNoV, digest and connect to the prokaryotic expression vector pGEX-6P-1, transform the correctly identified recombinant plasmid into BL21 ( DE3) competent cells.Pick out and shake the monoclonal bacteria, and add IPTG to induce recombinant GST-VP2. The fusion protein was expressed, purified by GST affinity chromatography and digested to obtain GII.4 HuNoV VP2 protein. The relative molecular mass (Mr.×10 3) of the purified HuNoV VP2 protein was analyzed by SDS-PAGE. BALB/c mice were immunized with purified GII.4 HuNoV VP2 protein (0.5 mg/ml) to prepare polyclonal antibodies. Results:The VP2 protein of GII.4 HuNoV was successfully expressed and purified, with a relative molecular mass (Mr.×10 3) of about 29; the VP2 polyclonal antibody of GII.4 HuNoV was successfully prepared and its titer was as high as 1∶1 280 000. Western blot and indirect ELISA analysis showed that the polyclonal antibody could specifically bind to the VP2 antigen of GII.4 HuNoV. Conclusions:The purified GII.4 HuNoV VP2 after prokaryotic fusion expression can be used to prepare high titer polyclonal antibody.

Objective:To understand the prevalence of human parechovirus (HPeV) in neonates of Hunan Provincial People’s Hospital, and analyze genetic evolutionary characteristics.Methods:From June to September 2021, fecal samples of inpatient neonates were collected in Hunan Provincial People′s Hospital. TaqMan real-time qPCR and RT-PCR were used for HPeV screening and genotyping. High-throughput sequencing and PCR were used to obtain whole genomes. Phylogenetic analysis was performed after sequencing.Results:A total of 123 fecal samples of neonates were collected, of which 22 were HPeV positive, with 17.89% positive rate. All the strains belonged to the HPeV-1 genotype. One full-length genomic sequence of 7 269 bp were obtained, and provisionally named Hunan/HPeV/2021, which has the highest nucleotide identity with known HPeV-1 genotype, with 86.6%-91.9% nucleotide identity. The nucleotide and amino acid identity of open reading frame (ORF) with known similar sequences were 90.3%-92.6% and 97.3%-98.3%, respectively. The phylogenetic analysis showed that Hunan/HPeV/2021 belongs to the HPeV-1 genotype, which is clustered into the same clade as the popular HPeV-1 strains in China.Conclusions:HPeV has a high prevalence in inpatient neonates of Hunan Provincial People’s Hospital and belong to the HPeV-1 genotype.

Objective:To express and purify VP7 protein of group A rotavirus (RVA) G1P[8]. The VP7 polyclonal antibody was prepared and its function was evaluated.Methods:The G1 VP7 protein was expressed by baculovirus expression system and purified by affinity chromatography. Polyclonal antibody against G1 VP7 was obtained by immunizing rabbits with G1 VP7 protein. The function of the G1 VP7 polyclonal antibody was verified by Western blotting (WB), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence assay.Results:The soluble G1 VP7 protein of human RVA G1P[8] was obtained using the baculovirus expression system and the VP7 protein was mainly in trimer state. The G1 VP7 polyclonal antibody was prepared and displayed relatively high binding titer to G1 VP7 protein by ELISA. The VP7 polyclonal antibodies could recognize multiple G-type RVAs by WB and ELISA. Immunofluorescence assay further demonstrated that G1 VP7 polyclonal antibody can bind to different RVAs, including Wa (genotype G1P[8]), DS-1(genotype G2P[4]), SA11 (genotype G3P[2]), and human G9P[8] RV strains. In addition, double sandwich ELISA showed that VP7 polyclonal antibody could be used to detect rotavirus in clinical samples.Conclusions:The soluble G1 VP7 protein was successfully expressed and VP7 antibody was obtained. The G1 VP7 polyclonal antibody could bind to a variety of G-type rotaviruses, which lays a foundation for the establishment of detection method of different G type rotaviruses.

Objective:To analyze the evolution of predominant Norovirus strain GⅡ.4 Sydney[P31] from 2017 to 2020 in China.Methods:Universal primers and next-generation sequencing technology were applied to establish Norovirus genogroup Ⅱ genome amplification method . Phylogenetic and key sites were analyzed on GⅡ.4 Sydney[P31] strains.Results:Among the 8 GⅡ.4 Sydney[P31] strains, 6 were successfully amplified and the genome sequences were obtained using the preliminarily established GⅡ genome amplification method . Phylogenetic analysis showed that the 6 strains obtained in this study from 2017-2020 strains grouped with the 2015-2019 GⅡ.4 Sydney[P31] reference strains in one cluster, and the Chinese strain GZ20133135 in 2013 and the 2012-2014 GⅡ.4 Sydney[P31] reference strains grouped into another one. A mutation Asp372Asn was found adjacent to the HBGA binding site Ⅱ. Epitope analysis showed that strains after 2017 have developed several aa mutations in A epitopes (297, 372, and 373), B epitopes (333), E epitopes (414), and H epitopes (309, 310), wherein the 2020 strains 20HN261 and 20HN253 have new changes in the A epitope (368) and G epitope (355) compared with the previous strains.Conclusions:The key mutation sites of the Chinese predominant Norovirus strain GⅡ.4 Sydney[P31] have been determined, which provides a scientific basis for tracking the emergence of new strains, and provides basic data for the development of vaccines against epidemic strains in China.