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:A subunit vaccine against SARS-CoV-2 BA.2 variant was prepared by prokaryotic expression system and its immunogenicity was evaluated.Methods:The recombinant plasmid of BA.2 variant RBD and the tandem of RBD and TT-P2 epitopes was constructed by molecular cloning technology, and recombinant proteins So and Sot were obtained by protein purification technology. Mice were immunized by intramuscular injection after mixing protein So/Sot as immunogens with Al(OH) 3 adjuvant to evaluate the effect of cellular and humoral immunity. Results:High purity soluble protein were obtained by dialysis and renaturation after expressed by prokaryotic system. The number of antigen-specific T lymphocytes secreting IFN-γ and IL-4 (213.7±0.6 and 311.7±1.5) in the Sot group induced by mice was significantly higher than that in the So group (94.3±16.8 and 185.7±4.2) ( P<0.001). The serum antibody level induced by Sot group was higher than that in the So group, the geometric mean titer (GMT) of neutralizing antibodies against BA.2 strain were 588 and 337, respectively ( P<0.05). Sot protein induced Th1/Th2 mixed type immune response with the predominance of Th2 type. Conclusions:The protein subunit vaccine expressed by the prokaryotic system have excellent cellular and humoral immunogenicity, which provides a strong theoretical basis for the development of the protein subunit vaccines of the SARS-CoV-2 Omicron variant.

Objective:To analyze the growth characteristics of different genotypes of Japanese encephalitis virus (JEV) in different cell lines, and to provide scientific basis for the selection of cell lines in the study of JEV.Methods:BHK-21, Vero, C6/36, PK-15, DF-1, N2a, SH-sy5y and MDCK cell lines were selected. The proliferation ability of genotype 1 (NX1889 strain), genotype 3 (P3 strain) and genotype 5 (XZ0934 strain) JEV in these cell lines was evaluated by plaque assay and RT-qPCR.Results:Significant cytopathogenic effects (CPE) were observed in BHK-21, Vero, C6/36, DF-1, N2a and PK-15 cell lines across all three JEV genotypes. However, no significant differences in CPE characteristics were observed within the same cell line. SH-sy5y and MDCK cell lines did not show significant CPE, but virus proliferation was detected in SH-sy5y cell line, while MDCK cell line were found to be insensitive to JEV. No significant difference was observed in the proliferation curves of G1, G3 and G5 JEV in BHK-21, Vero and SH-sy5y cell lines. In C6/36 and PK-15 cell lines, the titer of G1 JEV was higher than that of G3 and G5. In DF-1 cell line, G5 demonstrated a higher titer than the other two genotypes, whereas in N2a cell line, G5 showed a lower titer than the other two.Conclusions:There are differences in the proliferation of three different genotypes of JEV in different cell lines, which can provide reference for the study of JEV in different directions.

Objective:To analyze the whole genome sequence and key site mutations of hepatitis B virus (HBV) in patients with different stages of disease progression, and to understand the relationship between HBV genetic characteristics and disease progression.Methods:Serum samples and basic information of hepatitis B patients with asymptomatic HBV carrier, chronic hepatitis B patients, cirrhosis patients and primary hepatocellular carcinoma patients were collected. Nested PCR was used to amplify the samples to obtain HBV whole gene sequences. Phylogenetic trees were constructed to determine the genotype of the samples, and gene mutations of the samples were analyzed combined with reference sequences of each type.Results:A total of 256 samples were successfully amplified, including 68 asymptomatic HBV carrier patients, 118 CHB patients, 15 LC patients and 55 HCC patients, and five genotypes (B, C, D, I and C/D) were detected. The result of comparative analysis showed that the mutation rate of 56 nucleotide sites was significantly different among the four groups ( P<0.05). In addition to the discovery of C105T, A1762T/G1764A and G1899A and other previously reported key site mutations, the mutation rates of T53A, C1485T and C1628T in newly diagnosed HCC group were significantly higher than those in other groups, and the mutation rates of T2150G and T2151C in asymptomatic HBV infection group were significantly higher than those in other groups. A total of 26 sequences were deleted, mainly distributed in the pre-C and pre-S regions. The deletion mutation rate in the HCC group was significantly higher than that in the other groups. Conclusions:The data of this study indicate that some nucleotide substitution mutations and deletion mutations may be closely related to the occurrence and development of HBV-related diseases, and HCC patients are more likely to have gene mutations than non-HCC patients. These result provide a reference for understanding the relationship between viral mutation and the progression of HBV infection-related diseases.

Objective:A genome-wide molecular characterization of FJ21351116, a strain of G3P[8]-E2 2021 collected in Fujian, China, was performed.Methods:Whole genome sequencing of FJ21351116 was performed using a high-sensitivity group A rotavirus whole genome sequencing method. Genomic characteriza-tion of the virus was assessed by nucleic acid sequence analysis using MEGA 11.0, Geneious 9.0.2 and DNASTAR software. Neutralization epitopes of VP7 and VP4 (VP8*) were analyzed using BioEdit v. 7.0.9.0 and PyMOL v. 2.5.2.Results:In this study, FJ21351116 was shown to be a G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 genotype, and the result of phylogenetic tree showed that the VP7, VP4, VP3, and NSP2-NSP5 genes of the FJ21351116 strain were related to the equine-like DS-1-like G3P[8] genes that have been detected in Japan in recent years. VP6, VP1, VP2, and NSP1 genes are closely related to G2P[4] in most countries, especially in Singapore, suggesting that this strain was formed by genetic reassortment during the evolution of equine-like G3P[8] and G2P[4]. Evolutionary relationships between the VP7/VP4 genes of FJ21351116 and Rotarix and RotaTeq vaccines suggest that the multiple mutations in both VP7 and VP4 (VP8*) neutralizing antigenic epitopes and vaccine amino acid sites. It is hypothesized that the Rotarix and RotaTeq vaccines may be less effective against equine DS-1-like G3P[8] RVA, and the sequence differences with Rotarix are higher than those with RotaTeq.Conclusions:In this study, we found a rare case of DS-1-like G3P [8] RVA strain in China. Currently, horse-like DS-1-like G3P [8] RVA is relatively rare in China and may be poorly protected by vaccine strains, emphasizing the importance of continuous monitoring of RVA strains and the development of efficient and full-coverage RVA vaccines.

Objective:To understand the medical care of patients with sporadic Creutzfeldt-Jakob disease in China and its relationship with survival time.Methods:A retrospective analysis was performed on data of 150 patients with sporadic Creutzfeldt-Jakob disease diagnosed by China′s Creutzfeldt-Jakob Disease Surveillance Network during the period of January 1, 2021 to December 31, 2022 in this study, and telephone follow-up with family members was used to obtain information of the patients′ care, treatment, and survival after diagnosis. Survival was estimated by life table method, median survival time and 95% confidence interval ( CI) were calculated by Kaplan-Meier method, log-rank method was used to compare the difference in survival time between different groups, and multifactorial analysis was performed by COX proportional risk regression model regarding the influencing factors on patients′ survival time. Results:The median survival time of 150 patients with sporadic Creutzfeldt-Jakob disease was 6 months, and the cumulative lifetime survival rates at 2, 6, 12, and 18 months were 62%, 39%, 22%, and 9%, respectively. The result of univariate analysis showed that the differences in survival time between groups with the presence or absence of cortical blindness in the first symptom, the presence or absence of respiratory support (oxygen therapy), the presence or absence of adjunctive medication, and the presence or absence of tube feeding (nasogastric) were meaningful ( P<0.1). Multifactorial COX regression analysis showed that the risk of death in patients without adjuvant medication was 1.429 times higher than that in patients with adjuvant medication (95.0% CI: 1.014-2.014), and the risk of death in patients without tube feeding (nasal feeding) was 1.479 times higher than that in patients with tube feeding (nasal feeding) (95% CI: 1.052-2.081). Conclusions:Whether or not adjuvant medication is administered and whether or not tube feeding (nasogastric) is used are factors that affect survival time in patients with sporadic Creutzfeldt-Jakob disease, and the administration of appropriate adjuvant medication and tube feeding (nasogastric) may contribute to prolonging survival time in patients with sporadic Creutzfeldt-Jakob disease.

Objective:To understand the composition of respiratory virus spectrum in hospitalized children with acute respiratory infections in Guilin City from 2021 to 2022, and to explore the epidemic characteristics of different respiratory viruses.Methods:Information of a total of 638 hospitalized children with acute respiratory infections (ARI) syndrome under the age of 14 years in Guilin city, Guangxi from September 2021 to October 2022 was collected as research data. The collected pharyngeal swabs from pediatric patients were subjected to real-time fluorescence reverse transcription polymerase chain reaction for nucleic acid testing, screening for 15 common respiratory viruses, and analyzing the virus spectrum characteristics of hospitalized pediatric patients with acute respiratory infections.Results:Among the 638 specimens, 365 were tested positive for at least one virus, with a positive rate of 57.21% (365/638). The detection rate for two or more viruses was 12.85% (82/638). There were 12 types of viruses detected, and the difference in virus detection rates among different seasons was statistically significant (P<0.002). The virus positive detection rate of samples from different age groups was the highest in the 0-2-year old group (40.66%), followed by the 3-5-year old group (34.80%) and the 6-year and older group (24.54%).Conclusions:During the period from September 2021 to October 2022, all 12 respiratory viruses were prevalent in Guilin area, with obvious summer peak as characteristics. It is suggested that corresponding prevention and control measures should be focused on pathogens that may cause acute respiratory infections in children during the local summer to prevent and control the spread and prevalence of respiratory infections.

Objective:To understand the epidemiology of rubella and the genetic characteristics of the virus circulating during the period 2021-2022, providing basic scientific data for rubella prevention and control in China.Methods:National rubella incidence data for the period 2021-2022 were obtained from the Infectious Disease Surveillance System module and the Surveillance Report Management module of the China′s Disease Prevention and Control Information System. Positive rubella virus(RuV)isolates were obtained from the National Measles/Rubella Laboratory Network. Two nucleotide (nt) fragments [F1-480 (8 633-9 112 nt) and F2-633 (8 945-9 577 nt)] located in the E1 gene were amplified and determined by reverse transcription polymerase chain reaction (RT-PCR), and the target gene (E1-739) was obtained after collating and splicing. The sequences obtained in this study were used to construct a phylogenetic tree with the reported reference strains for genotype and lineage identification. Additionally, the phylogenetic analysis was performed to assess their genetic relatedness of RuV strains prevalent in China during 2018-2020 from GenBank database.Results:In 2021-2022, the rubella incidence in China was 0.06/100, 000 (2021: 840 cases; 2022: 784 cases), with cases primarily concentrated in the western and southern provinces. Age distribution analysis showed that rubella cases in 2021-2022 was mainly in children under 5 years of age (2021: 34.17%, 287/840; 2022: 42.09%, 330/784), with the highest proportion in children aged 0-2 years. Further analysis of the immunization history of cases revealed that in the 8-23 months age group, a significant proportion of cases had received only one dose of rubella containing vaccine (RCV); cases in the 2-14 years age group were mainly among children who had received two or more doses of RCV; however, cases over 15 years of age were primarily found in individuals who had not received RCV or had unknown immunization history. National virological surveillance data showed that totally 22 RuV virus isolates were obtained, from 6 provinces in China during 2021-2022, which belonged to lineage 1E-L2 (11 strains) and 2B-L2c (11 strains). And these viruses displayed high genetic homology with RuV prevalent from 2018 to 2020.Conclusions:The incidence of rubella in China was maintained at a low level during 2021-2022, and the prevalent RuV strains were lineage 1E-L2 and 2B-L2c.

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 prepare monoclonal antibodies specific to human papillomavirus type 6 L1 (HPV6 L1) protein, investigate the binding characteristics, cross-reactivity, and neutralization efficacy of these antibodies.Methods:Antibody genes were extracted from the spleen cells of mice immunized with HPV6 L1 protein and used to construct an ScFv phage antibody library. The library was enriched and screened using HPV6 L1 protein. Following expression of the antibody genes into murine IgG, the binding properties of the antibodies to the L1 protein and their neutralization effects on pseudoviruses were verified.Results:An ScFv antibody library targeting HPV6 L1 was successfully constructed with a capacity of 6.54×10 7. After screening with HPV6 L1, two antibody strains were obtained, named Q9 and Q11. ELISA testing revealed that Q9-IgG has a high antibody titer (about 10 6) against HPV6 L1, while cross-reactivity titers to HPV18 and 45 L1 were 10 2. Q11-IgG has an antibody titer about 4×10 4 against HPV6 L1, but not combined with the L1 proteins of other HPV types. Pseudovirus neutralization assays indicated that Q9-IgG lacked neutralizing activity, while Q11-IgG showed a neutralizing antibody titer of 10 4.5against HPV6 pseudovirus. Conclusions:Both Q9 and Q11 are monoclonal antibodies specific to HPV6 L1. However, they displayed notable differences in cross-reactivity, antigen recognition sites, and neutralization efficacy. These antibodies provide essential tools for the foundational research of HPV6, immunological diagnosis, and the development of therapeutic formulations.