Mucosal immune system is an important part of the body′s immune system, and mucosal tissues that are widely distributed in the respiratory tract, digestive tract and urogenital tract are the main places where local specific immune responses occur. Mucosal surface is the gateway to direct contact with external pathogens, and most pathogens invade the body through mucous membranes, so mucosal immunity is the first line of defense against pathogen infection. Mucosal vaccines offer the potential to generate a strong protective immune response at the primary site of pathogen infection, but there are very limited mucosal vaccines currently on the market. In this paper, the composition of mucosal immune system, antigen uptake, and challenges in the development of mucosal vaccines are reviewed, which provides ideas for further research of mucosal vaccines.

Objective:To analyze the genetic characteristics of influenza B virus Victoria lineage in Ma′anshan from 2019 to 2022.Methods:Throat swabs were collect from cases with influenza-like illness in three sentinel hospitals and from influenza outbreak events in Ma′anshan city from 2019 to 2022. Real-time fluorescence-based PCR was performed to detect the nucleic acids of influenza viruses in the swab samples. Statistical analysis was conducted using the influenza year as the detection cycle. MDCK cells and chicken embryos were used for virus isolation, and 31 strains of B/Victoria lineage were selected for whole-genome sequencing and genetic analysis.Results:A total of 11 258 throat swabs were collected from ILI cases, and 8.90% (1 002/11 258) of them tested positive for B/Victoria. Except for the period from the winter of 2020 to the spring of 2021, during which no epidemic outbreak of influenza was observed, there were peaks in the prevalence of B/Victoria influenza in winter and spring of the other years, with the positive rates ranging from 12.65% (54/427) to 46.68% (176/377) during peak seasons. Compared with the recommended vaccine strains, the homology of the HA gene nucleotides of the viral strains isolated from 2019 to 2022 ranged from 98.40% to 99.26%, and the homology of amino acids ranged from 96.21% to 98.80%. All isolated strains carried mutations in the 190-helix of the hemagglutinin protein; the strains isolated from 2019 to 2020 had two amino acid insertions at position 160-loop; and the strains isolated from 2021 and 2022 had mutations at positions 120-loop and 150-loop. No drug-resistant mutations were detected in the neuraminidase gene.Conclusions:The B/Victoria strains isolated in Ma′anshan city from 2019 to 2022 have key site variations as compared with the recommended vaccine strains, suggesting a decrease in vaccine immune efficacy. Therefore, it is necessary to strengthen the surveillance of viral mutations to provide reference for updating vaccine strains and formulating epidemic prevention and control measures.

Objective:To obtain a prevalent respiratory syncytial virus (RSV) clinical isolate in Beijing and analyze the genotype and biological characteristics of the strain.Methods:A nasopharyngeal secretion specimen was collected from a child with RSV infection in Beijing in 2023 and used for viral isolation. Viral nucleic acid was amplified using qRT-PCR. The isolated virus was identified by transmission electron microscopy, indirect immunofluorescence assay, and plaque formation assay. A phylogenetic analysis was conducted based on the whole-genome sequencing results. Virus titers were determined, and replication characteristics were analyzed. The efficacy of the isolated strain for in vitro screening of antiviral drugs was validated. Results:A clinical RSV isolate, named hRSV/C-Tan/BJ 202301, was successfully isolated, which could form syncytia in Hep-2 cells. Spherical, filamentous, and irregular virus particles were observed by electron microscopy. Immunofluorescence detection showed green fluorescence in Hep-2 cells, and plaque assay showed round plaques, which were similar to the Long strain in morphology. Genomic sequence analysis showed that it belonged to ON1 genotype. It exhibited similar cell growth kinetics characteristics with the Long strain and could be used for antiviral drug screening in vitro. Conclusions:In this study, one RSV strain is successfully isolated and identified. The biological characteristics and the phylogenetic relationship of this strain reflect the characteristics of the circulating strains in Beijing, which provides experimental material for RSV vaccine development and antiviral drug screening in China.

Objective:To investigate the underlying mechanism behind the significant reduction in intracellular virus loads after respiratory syncytial virus (RSV) and influenza viruses infect respiratory epithelial cells overexpressing the chemokine (C-C motif) receptor 1 (CCR1).Methods:A549 cells were infected with respiratory syncytial virus (RSV), influenza A viruses (H1N1, H3N2), or influenza B virus (FluB), and the expression of chemokine (C-C motif) ligand 5 (CCL5) and CCR1 were detected by qRT-PCR, ELISA, and Western blot. After overexpressing or knocking down CCR1 in A549 cells, these cells were infected with RSV, H1N1, H3N2, or FluB, and the expression of CCR1, heat shock protein 90 (HSP90), cyclin-dependent kinase 1 (CDK1), and viral proteins were detected by qRT-PCR and Western blot. After stimulating CCR1-overexpressed A549 cells with CCL5, Western blot was used to detect the expression of HSP90 and CDK1, and co-immunoprecipitation was used to detect the interaction between HSP90 and CCR1. CCR1 -/- mice were infected with RSV, H1N1, or H3N2 to observe the changes in the expression of HSP90, CDK1, and viral proteins with Western blot, and the inflammation in lung tissues with HE staining. One-way analysis of variance and t test were used for statistical analysis. Results:RSV, H1N1, H3N2, and FluB infections induced high expression of CCL5 in A549 cells ( P<0.05), but the expression of CCR1 showed an overall downward trend. After activating its receptor CCR1, CCL5 inhibited the replication of RSV and influenza viruses by suppressing the activity of HSP90 ( P<0.05). The experiments conducted on CCR1 -/- mice confirmed that the enhanced activity of HSP90 facilitated the replication of RSV and influenza viruses. Conclusion:RSV and influenza viruses may reduce the binding of CCL5 to CCR1 by downregulating the expression of CCR1 in respiratory epithelial cells, thereby weakening the inhibitory effect of CCR1 on HSP90 activity, which enables them to evade host immune defense.

Objective:To investigate the effect of curcumin on phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway on the autophagy of Bacille Calmette-Guérin (BCG)-infected macrophages.Methods:The infection model was established by infecting THP-1-derived macrophages with BCG. Five groups were involved in this study, which were control group, BCG group, BCG+ curcumin group, BCG+ curcumin+ IGF-1(PI3K agonist) group, and BCG+ curcumin+ LY294002 (PI3K inhibitor) group. The fluorescence intensity of autophagosomes was observed under fluorescence microscope using the fluorescent dye monodansylcadaverine (MDC staining). The expression of PI3K, Akt, mTOR, phospho-PI3K (p-PI3K), phospho-Akt (p-Akt), phospho-mTOR (p-mTOR), microtubule-associated protein 1 light chain 3-Ⅱ (LC3-Ⅱ), and Beclin-1 at protein level were detected by Western blot. Colony forming unit was used to detect macrophage load. Multiple independent, normal, and homogeneous data were compared using one-way analysis of variance, and pairwise comparisons were conducted using LSD test.Results:BCG infection significantly decreased the fluorescence intensity of autophagosomes, and the expression of autophagy marker proteins LC3-Ⅱ and Beclin-1 ( P<0.05), but increased the expression of p-PI3K, p-Akt, and p-mTOR ( P<0.05). Curcumin increased the fluorescence intensity of autophagosomes and enhanced the expression of LC3-Ⅱ and Beclin-1 proteins in a concentration-dependent manner ( P<0.05). Besides, curcumin inhibited the expression of p-PI3K, p-Akt, and p-mTOR ( P<0.05). The PI3K agonist IGF-1 reversed the above effects of curcumin. Compared with the BCG+ curcumin group, the fluorescence intensity of autophagosomes and the expression of LC3-Ⅱ and Beclin-1 proteins were further increased ( P<0.05), while the expression of p-PI3K, p-Akt and p-mTOR was further decreased ( P<0.05) in the BCG+ curcumin+ LY294002 group. Compared with the BCG group, the bacterial loads in the BCG+ curcumin group and the BCG+ curcumin+ LY294002 group decreased significantly ( P<0.05), while the bacterial load in the BCG+ curcumin+ IGF-1 group increased significantly ( P<0.05). Conclusions:Curcumin can promote the autophagy of BCG-infected macrophages, which contributes to the clearance of Mycobacterium tuberculosis by macrophages. Part of the mechanism may be related to the inhibition of PI3K/Akt/mTOR pathway.

Objective:To analyze the epidemiological characteristics of influenza A virus (FluA), influenza B virus (FluB), and respiratory syncytial virus (RSV) in cases with influenza-like illness in the fever clinic of a tertiary hospital in Shanghai in order to provide reference for the prevention and control of influenza virus and RSV infections.Methods:Oropharyngeal swabs were collected from cases with influenza-like illness who were treated in Shanghai Pulmonary Hospital from February 2023 to May 2024. The nucleic acids of FluA, FluB, and RSV were detected by GeneXpert test. The demographic features including age and gender, and the epidemiological characteristics of viral infections and mixed infections in these patients were analyzed.Results:A total of 11 094 patients were tested for the nucleic acids of FluA, FluB, and RSV, and the positive rates were 36.82% (4 085/11 094), 9.70% (1 076/11 094), and 1.44% (160/11 094), respectively. During the period from February 2023 to May 2024, FluA mainly circulated in winter and spring, reaching its peak in March 2023 (74.51%, 766/1 028) and mainly affecting individuals aged 0 to 18 (45.62%, 198/434). FluB infection mainly occurred in winter, peaking in January 2024 (32.73%, 547/1 671) with the highest positive rate among individuals aged 19 to 44 (12.98%, 857/6 601). As few children were involved in this study, RSV infection was mainly detected in the elderly over 60 years old (3.19%, 94/2 950), and the positive rate was less than 5% every month. Co-infection of two viruses (24 cases) were occasionally detected.Conclusions:From 2023 to 2024, a large-scale influenza virus epidemic appears in Shanghai area, with FluA and FluB alternately being the dominant strain, and the positive rate of RSV remains at a low level, showing a sporadic pattern. The main age groups affected by different pathogens vary, and strengthened surveillance is still needed in the future.

Objective:To establish and optimize a novel method, focus forming assay (FFA), for quantitation of influenza A virus (FluA) and compare its application performance with traditional plague forming assay (PFA).Methods:The foci chromogenic effects of three peroxidase substrates in immunostaining were compared. The PFA and FFA methods were used to explore FluA incubation times and plaque morphology on 12-well plates, and to determine optimal incubation times and virus adsorption volumes for different FluA subtypes on 96-well plates. The correlation between FFA and PFA was evaluated, and the optimized FFA was applied to the in vitro antiviral efficacy analysis of Favipiravir and neutralization test against different subtypes of FluA. Results:TRUEBLUE substrate was identified as the optimal substrate for foci visualization. Compared with the PFA, the FFA showed improved sensitivity and reduced detection time in FluA titration, and good correlation was shown between the two methods′ results. By replacing the 96-well plate with the 12-well plate for FFA titration of different subtypes of FluA, the detection time was shortened, and the amount of serum samples used could be further reduced by optimizing the virus adsorption volume. The half-maximal effective concentration of favipiravir against influenza viruses assessed by the FFA and PFA methods showed no significant difference, and was consistent with the results obtained from quantitative PCR. Additionally, the focus reduction neutralization test and hemagglutination inhibition assays demonstrated strong correlation in determining antibody titers against FluA in serum neutralization assays.Conclusions:The improved FFA method developed here provides a more efficient experimental tool for FluA titration, antiviral drug screening and broad-spectrum vaccine evaluation.

Objective:To construct a model of mitochondria-related genes (Mito-RGs) in hepatocellular carcinoma (HCC), and predict the immune, prognostic and therapeutic characteristics of HCC based on the model, so as to provide a new idea for the diagnosis and treatment of HCC.Methods:The expression profiles of HCC and corresponding clinical information were obtained from the Cancer Genome Atlas (TCGA) database. Univariate Cox regression, Least Absolute Shrinkage and Selection Operator (LASSO) regression and multivariate Cox regression were used to construct a prognostic model of HCC based on Mito-RGs, and the International Cancer Genome Consortium-Liver Cancer-RIKEN-Japan ICGC-LIRI-JP dataset were used for validation. GO and KEGG analyses were performed to investigate the signaling pathways enriched for differentially expressed genes in the high- and low-risk groups. Immune infiltration was assessed using CIBERSORT. Single-cell data were used to study the proportion of immune cells in high- and low-risk groups of HCC samples and the relationship with cell proliferation. Cellminer was used to assess the relationship between risk score models and drug sensitivity.Results:A risk-prognostic model of HCC containing seven Mito-RGs ( DTYMK, ACADS, HMGCS2, CYP27A1, TOMM40L, STOM, and AKR1B10) was constructed. High-risk HCC patients had a worse prognosis. Genes upregulated in the high- and low-risk groups of differentially expressed genes were enriched in cell cycle and metabolism-related pathways. Single-cell data showed higher proportions of CD8 + T cells, macrophages and monocytes, and proliferating cells in the high-risk group. CIBERSORT analysis suggested that Treg cells and M0 macrophages were more abundant in the high-risk group, whereas CD8 + T cells and CD4 + memory T cells were less abundant. Patients in the high-risk group were more sensitive to myeloid cell leukemia sequence 1 inhibitor, vincristine, phosphatidylinositol kinase beta subunit inhibitor, and aurora kinase A, while trametinib, selumetinib, extracellular regulated protein kinase, and mitogen-activated extracellular signal-regulated kinase were more effective in the low-risk group. Conclusion:The constructed Mito-RGs model is capable of providing a more accurate assessment of the prognosis and the degree of immune cell infiltration in HCC patients.

Men who have sex with men (MSM) represent a high-risk group for human papillomavirus (HPV) infection and transmission. HPV vaccination for MSM has been extensively explored in clinical trials and real-world settings in foreign countries, but it has not been widely promoted for MSM in the Chinese mainland. This article provides a comprehensive review of the HPV vaccination status among MSM, as well as the effectiveness, immunogenicity, safety, and cost-effectiveness of HPV vaccines, aiming to provide reference for the implementation and promotion of HPV vaccination among MSM in the Chinese mainland.

Objective:To explore the epidemiological characteristics of human metapneumovirus (hMPV) in children hospitalized for acute respiratory tract infections in Hebei, and provide a theoretical basis for the clinical diagnosis and treatment of acute respiratory tract infections in children in Hebei.Methods:Retrospectively, 41 499 children hospitalized in Hebei Children′s Hospital for acute respiratory tract infections from January 2017 to December 2021 were included to analyze the morbidity of children of different genders and ages, and in different seasons, and to statistically analyze the epidemiological data such as the positive detection rate of hMPV, the detection rates of mixed infections with other pathogens, and the clinical diagnosis.Results:The overall positive detection rate of hMPV in hospitalized children with acute respiratory infections from 2017 to 2021 was 5.94%(2 464/41 499), with the highest positive detection rate of hMPV in the age group of 3 to 4 years (7.66%, 520/6 789) and the lowest in the age group of ≥5 years (2.89%, 180/6 225), with a statistically significant difference ( P<0.001); the positive detection rates in male and female children were respectively 5.97%(1 496/25 056) and 5.94%(968/16 443), and the difference was not statistically significant ( P>0.05). The positive detection rates of hMPV from 2017 to 2021 were 5.10%(408/7 998), 9.64%(915/9 491), 4.27%(426/9 969), 5.91%(368/6 226), and 4.44%(347/7 815), respectively, and the positive detection rate of hMPV in 2018 was significantly higher than that in the other years ( P<0.001). hMPV circulated throughout the year, with obvious seasonality, with the highest positive detection rate in spring and winter.The mixed detection rate of hMPV with other respiratory pathogens was 42.74% (1 053/2 464), of which mixed detection with rhinovirus was the most common, with a mixed detection rate of 48.24%(508/1 053).Clinical diagnosis of hPMV-positive children was mostly bronchopneumonia. Conclusions:hMPV is one of the important pathogens in hospitalized children with acute respiratory infections in Hebei, which is common in children under 5 years of age and can occur throughout the year, with peak epidemics in winter and spring. Mixed infections of hMPV with other respiratory pathogens are common and can increase the risk of worsening clinical symptoms in children.