Objective:To investigate the genotype and epidemiological characteristics of human metapneumovirus (HMPV) among hospitalized cases with acute respiratory infections (ARI) in children in Changchun City, Jilin Province, China.Methods:From June 2019 to June 2023, throat swabs of ARI inpatients in Changchun Children′s Hospital were collected, and their epidemiological and clinical information were also collected. Quantitative reverse transcription-PCR was used to identify HMPV-positive cases, followed by the amplification of the G gene and genetic analysis in the HMPV-positive cases.Results:A total of 3 311 children hospitalized with ARI were included in this study. Their age ranged from 0 to 17 years old, and the M ( Q1, Q3) of age was 2 (1, 3) years. About 1 811 (54.70%) cases were males. A total of 167 HMPV-positive cases were detected with a positive rate of 5.04%, of which 92.81% (155/167) were children under 5 years old. The positive rate of HMPV in 2019 was 6.37% (30/471), which dropped to the lowest in 2020 (2.31%, 10/432). The HMPV-positive rate was then rebounded in 2021 (4.70%, 60/1 277) and 2022 (4.56%, 21/461), which increased to 6.87% (46/670) in 2023. The difference in HMPV-positive rate among each year was statistically significant ( P<0.05). The prevalence peak of HMPV varied in different years, showing either a unimodal or bimodal distribution in one year. A total of 79 HMPV G gene sequences were obtained, of which subtype A and subtype B accounted for 48.10% and 51.90%, respectively. All of the subtype A sequences were clarified as A2c duplicated variants, and subtype B was mainly B2 genotype. Besides, subtypes A and B were prevalent alone or co-circulated in different years, and there was a subtype replacement pattern in HMPV. Conclusion:The positive rate of HMPV in hospitalized ARI cases in children is significantly different from 2019 to 2023 in Changchun City. Notably, there are certain switch patterns of HMPV subtypes A and B in different years.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among acute respiratory infection (ARI) cases in 16 provinces of China from 2009 to 2023.Methods:The data of this study were collected from the ARI surveillance data from 16 provinces in China from 2009 to 2023, with a total of 28 278 ARI cases included in the study. The clinical specimens from ARI cases were screened for HRSV nucleic acid from 2009 to 2023, and differences in virus detection rates among cases of different age groups, regions, and months were analyzed.Results:A total of 28 278 ARI cases were enrolled from January 2009 to September 2023. The age of the cases ranged from<1 month to 112 years, and the age M ( Q1, Q3) was 3 years (1 year, 9 years). Among them, 3 062 cases were positive for HRSV nucleic acid, with a total detection rate of 10.83%. From 2009 to 2019, the detection rate of HRSV was 9.33%, and the virus was mainly prevalent in winter and spring. During the Corona Virus Disease 2019 (COVID-19) pandemic, the detection rate of HRSV fluctuated between 6.32% and 18.67%. There was no traditional winter epidemic peak of HRSV from the end of 2022 to the beginning of 2023, and an anti-seasonal epidemic of HRSV occurred from April to May 2023. About 87.95% (2 693/3 062) of positive cases were children under 5 years old, and the difference in the detection rate of HRSV among different age groups was statistically significant ( P<0.001), showing a decreasing trend of HRSV detection rate with the increase of age ( P<0.001). Among them, the HRSV detection rate (25.69%) was highest in children under 6 months. Compared with 2009-2019, the ranking of HRSV detection rates in different age groups changed from high to low between 2020 and 2023, with the age M (Q1, Q3) of HRSV positive cases increasing from 1 year (6 months, 3 years) to 2 years (11 months, 3 years). Conclusion:Through 15 years of continuous HRSV surveillance analysis, children under 5 years old, especially infants under 6 months old, are the main high-risk population for HRSV infection. During the COVID-19 pandemic, the prevalence and patterns of HRSV in China have changed.

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 investigate the genotype and epidemiological characteristics of human metapneumovirus (HMPV) among hospitalized cases with acute respiratory infections (ARI) in children in Changchun City, Jilin Province, China.Methods:From June 2019 to June 2023, throat swabs of ARI inpatients in Changchun Children′s Hospital were collected, and their epidemiological and clinical information were also collected. Quantitative reverse transcription-PCR was used to identify HMPV-positive cases, followed by the amplification of the G gene and genetic analysis in the HMPV-positive cases.Results:A total of 3 311 children hospitalized with ARI were included in this study. Their age ranged from 0 to 17 years old, and the M ( Q1, Q3) of age was 2 (1, 3) years. About 1 811 (54.70%) cases were males. A total of 167 HMPV-positive cases were detected with a positive rate of 5.04%, of which 92.81% (155/167) were children under 5 years old. The positive rate of HMPV in 2019 was 6.37% (30/471), which dropped to the lowest in 2020 (2.31%, 10/432). The HMPV-positive rate was then rebounded in 2021 (4.70%, 60/1 277) and 2022 (4.56%, 21/461), which increased to 6.87% (46/670) in 2023. The difference in HMPV-positive rate among each year was statistically significant ( P<0.05). The prevalence peak of HMPV varied in different years, showing either a unimodal or bimodal distribution in one year. A total of 79 HMPV G gene sequences were obtained, of which subtype A and subtype B accounted for 48.10% and 51.90%, respectively. All of the subtype A sequences were clarified as A2c duplicated variants, and subtype B was mainly B2 genotype. Besides, subtypes A and B were prevalent alone or co-circulated in different years, and there was a subtype replacement pattern in HMPV. Conclusion:The positive rate of HMPV in hospitalized ARI cases in children is significantly different from 2019 to 2023 in Changchun City. Notably, there are certain switch patterns of HMPV subtypes A and B in different years.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among acute respiratory infection (ARI) cases in 16 provinces of China from 2009 to 2023.Methods:The data of this study were collected from the ARI surveillance data from 16 provinces in China from 2009 to 2023, with a total of 28 278 ARI cases included in the study. The clinical specimens from ARI cases were screened for HRSV nucleic acid from 2009 to 2023, and differences in virus detection rates among cases of different age groups, regions, and months were analyzed.Results:A total of 28 278 ARI cases were enrolled from January 2009 to September 2023. The age of the cases ranged from<1 month to 112 years, and the age M ( Q1, Q3) was 3 years (1 year, 9 years). Among them, 3 062 cases were positive for HRSV nucleic acid, with a total detection rate of 10.83%. From 2009 to 2019, the detection rate of HRSV was 9.33%, and the virus was mainly prevalent in winter and spring. During the Corona Virus Disease 2019 (COVID-19) pandemic, the detection rate of HRSV fluctuated between 6.32% and 18.67%. There was no traditional winter epidemic peak of HRSV from the end of 2022 to the beginning of 2023, and an anti-seasonal epidemic of HRSV occurred from April to May 2023. About 87.95% (2 693/3 062) of positive cases were children under 5 years old, and the difference in the detection rate of HRSV among different age groups was statistically significant ( P<0.001), showing a decreasing trend of HRSV detection rate with the increase of age ( P<0.001). Among them, the HRSV detection rate (25.69%) was highest in children under 6 months. Compared with 2009-2019, the ranking of HRSV detection rates in different age groups changed from high to low between 2020 and 2023, with the age M (Q1, Q3) of HRSV positive cases increasing from 1 year (6 months, 3 years) to 2 years (11 months, 3 years). Conclusion:Through 15 years of continuous HRSV surveillance analysis, children under 5 years old, especially infants under 6 months old, are the main high-risk population for HRSV infection. During the COVID-19 pandemic, the prevalence and patterns of HRSV in China have changed.

Objective To investigate the relationship between serum microRNA(miR)-137 and miR-21 ex-pression and hypertensive retinopathy(HR).Methods A total of 123 hypertensive patients admitted to the hospital from March 2020 to August 2022 were selected as the hypertensive group and divided into HR and non-HR groups according to whether they were concomitant with HR,and another 58 healthy people who un-derwent the physical examination during the same period were selected as the control group.Clinical data of HR patients were collected and serum miR-137 and miR-21 expression was detected by real-time fluorescent quantitative PCR.The influencing factors of concurrent HR in hypertensive patients were analyzed,and receiv-er operating characteristic(ROC)curve was used for analzing predictive value of serum miR-137 and miR-21 expression in hypertensive patients with concurrent HR.Results Serum miR-137 and miR-21 relative expres-sion levels were higher in the hypertensive group than those in the control group(P<0.05).The incidence rate of HR in 123 hypertensive patients was 25.20%(31/123).Multivariate Logistic regression analysis showed that prolonged duration of hypertension and elevated systolic pressure,diastolic pressure,miR-137 rel-ative expression level,and miR-21 relative expression level were independent risk factors for HR in hyperten-sive patients(P<0.05).ROC curve analysis showed that the area under the curve(AUC)of serum miR-137 combined with miR-21 in predicting HR in hypertensive patients was 0.840,which was greater than 0.735 and 0.732 of the single detection of miR-137 and miR-21(P<0.05).Conclusion High expression of serum miR-137 and miR-21 is closely associated with hypertension complicating HR and may be an auxiliary predictor of HR.

Objective:This study comprehensively analyzed the genomic characterizations of human parainfluenza virus type 3 (HPIV3) strains circulating in six provinces and cities of China (Beijing, Henan, Jilin, Anhui, Gansu, and Shandong) during the period of 2019-2020. The aim was to elucidate the intricate genetic variations and molecular evolutionary trends within the HPIV3 genome.Methods:Based on genotypic differentiation, genetic divergence, and spatial and temporal distribution, 12 representative HPIV3 strains (including 7 of C3a subtype, 2 of C3b subtype and 3 of C3f subtype) were selected from the aforementioned provinces, and the complete genome sequence was successfully obtained by overlapping amplification of fragments using nested RT-PCR. Subsequently, a complete genome database of global representative HPIV3 strains was constructed and analyzed using bioinformatics tools.Results:The length of complete genome of the 12 HPIV3 strains in the present study varied between 15 227 bp and 15 370 bp, the G+ C content ranged from 35.1% to 35.3% and the nucleotide identity intermediated from 97.6% to 99.6%. Compared with the prototype strain (GenBank accession number: NC_001796.2), the nucleotide identity of 12 HPIV3 strains ranged from 94.2% to 94.5%. Analysis of the complete genome of HPIV3 available in China and globally showed that the genomic variation of HPIV3 was mainly shaped by substitution mutations, and no base deletions or gene recombination were observed.Only a six-base insertion (ATTAAA) was found in the F gene’s 3′UTR region of a representative strain originating from Jilin province (CHN/Jilin036/2019/C3b) in this study, and its potential pathogenic significance needs to be further investigated. Amino acid analysis of the encoded proteins revealed that the C3a lineage of HPIV3, widely prevalent both in China and worldwide, exhibits lineage-specific mutation sites in the N, P and L proteins. Furthermore, within the Chinese prevalent C3a strains, a distinctive mutation site (N216S) in L protein was also identified. Notably, specific variant sites have not been found in Chinese C3b and C3f branch strains. Based on the complete genome, the comprehensive evolutionary analysis showed that the time to the most recent common ancestor (tMRCA) of global HPIV3 strains was estimated to 1927 (95% HPD: 1901-1945), with an average molecular evolutionary rate of 5.29 × 10 -4 substitutions/site/year, while the average molecular evolutionary rate of HPIV3 strains in China is 5.24 × 10 -4 substitutions/site/year. In addition, each gene of HPIV3 was subjected to negative selection pressure, with the P, HN and F genes showing the most significant nucleotide variation and higher rates of molecular evolution than the other genes. Conclusions:This study reveals that the complete genome of HPIV3 strains circulating in six provinces and cities of China tend to evolve conservatively. Moreover, substitution emerge as the main driving force for molecular evolution of HPIV3.

Objective:To understand the common viral infection among the surveillance cases of fever respiratory syndrome (FRS) in nine provinces in China.Methods:The research data were obtained from nine provinces (Anhui, Beijing, Guangdong, Hebei, Hunan, Jilin, Shandong, Shaanxi and Xinjiang) in the "Infectious Disease Surveillance Technology Platform Information Management System" of the Chinese Center for Disease Control and Prevention from January 2009 to June 2021. Finally, 8 243 FRS cases with nucleic acid detection results of eight viruses [human influenza virus (HIFV), human respiratory syncytial virus (HRSV), human adenovirus (HAdV), human parainfluenza virus (HPIV), human rhinovirus (HRV), human metapneumovirus (HMPV), human coronavirus (HCoV) and human Boca virus (HBoV)] were included in the study. The χ 2 test/Fisher exact probability method was used to analyze the difference of virus detection rate in different age groups, regions and seasons. Results The M ( Q1, Q3) age of 8 243 FRS cases was 4 (1, 18) years old, and 56.56% (4 662 cases) were children under 5 years old. Males accounted for 58.1% (4 792 cases) of all cases. All cases were from outpatient/emergency department (2 043 cases) and inpatient department (6 200 cases). The virus detection rates of FRS cases from high to low were HRSV, HIFV, HPIV, HRV, HAdV, HMPV, HCoV and HBoV. Two or more viruses were detected simultaneously in 524 cases, accounting for 15.66% of virus-positive cases. The difference of the virus detection rate in different age groups was statistically significant (all P values<0.05), and the virus detection rate in children<5 years old was higher (49.96%). The positive rate of any virus in south China was higher than that in north China ( P<0.001). The virus-positive FRS cases were detected throughout the year. The detection rate of HRSV was higher in autumn and winter. The detection rate of HIFV was higher in winter. The detection rate of HMPV was higher in winter and spring. The detection rates of HPIV, HRV, HCoV and HBoV were higher in summer and autumn, while there was no significant difference in the detection rate of HAdV in different seasons. Compared with 2009-2019, the detection rate of any virus in 2020-2021 decreased from 41.37% to 37.86%. The detection rate of HIFV decreased sharply from 10.62% to 1.37%. The detection rate of HPIV decreased from 8.24% to 5.88%. The detection rate of HRV and HBoV increased from 5.43% and 1.79% to 9.67% and 3.19%, respectively. Conclusion:HRSV and HIFV infections are more common among FRS cases in nine provinces in China from 2009 to 2021, and the epidemiological characteristics of eight common respiratory viruses vary in different age groups, regions and seasons.

Objective:To understand the genetic characteristics of human adenovirus (HAdV) in severe acute respiratory infection (SARI) cases in Luohe city, Henan province, China.Methods:After viral isolation of HAdV-positive specimens identified in SARI cases from October 2017 to February 2019, the Loop2 region of the Hexon gene was amplified and determined to initially identify the virus type. Then, based on the preliminary screening result, the full length of the sequences of the three target genes (Penton base, Hexon and Fiber) of the viral strains were amplified using specific primers for each HAdV type, and phylogenetic and sequence homology analyses were performed with the prototype strains and the representative strains of the corresponding types at home and abroad to identify the types of viral strains and understand their genetic characteristics.Results:A total of 18 viral isolates were obtained from 27 HAdV-positive throat swab specimens from 783 SARI cases in Luohe city, Henan province, and the molecular typing result showed that these strains belonged to species B (HAdV-3, HAdV-7 and HAdV-55), species C (HAdV-1, P1H2F2, Px1/Ps3H5F5, P89H5F5 and HAdV-6) and species E (HAdV-4). Among them, the highest positive detection rate was found for species C HAdV-1 isolates (33.3%), followed by species B HAdV-3 (22.2%) and species C P1H2F2 (11.1%). The four HAdV strains in this study (HAdV-3, HAdV-4, HAdV-7 and HAdV-55) were characterized by significantly conserved and stable in time and space; while three patterns of genetic recombination (P1H2F2, Px1/Ps3H5F5 and P89H5F5) were identified for HAdV-C strains in this study, and their potential public health significance needed to be confirmed by further studies.Conclusions:The HAdV infection of SARI cases in Luohe city, Henan province during 2017-2019 was dominated by species C, followed by species B and species E. These data provided a scientific basis for the prevention and control of local adenovirus-associated infectious diseases.

Objective:To evaluate the effect of synthetic CpG oligodeoxynucleotide (CpG-ODN) as adjuvant on immune response induced by inactivated human adenovirus (HAdV)-55 antigen in BALB/c mice.Methods:HAdV-55 virus QS prototype strain was purified by plaque to construct a seed bank of vaccine candidate strain. The amplified product of vaccine candidate strain was inactivated by 0.05%β-propiolactone, and purified to prepare perfect virus particle antigen. The purified HAdV-55 antigen was mixed with the same volume CPG-ODN and aluminum hydroxide adjuvant in low-dose group (0.2 mg/ml) and high-dose group (1 mg/ml), respectively, and inoculated BALB/c mice after emulsification. Meanwhile, the control group was set with PBS, and the immunization was enhanced once every 21 days. Respectively on primary immune 21 and 35 days after collecting venous blood in mice and separation of serum, serum was collected at the end of the time of separating spleen lymphocytes in mice. The levels of HAdV-55 specific IgG antibody and neutralization antibody in serum of immunized mice were observed by ELISA and micro-neutralization test, and the levels of lymphocytes secreting IL-4 and IFN-γ cytokines were detected by ELISpot.Results:No matter with or without adjuvant, along with the increase of the number of immunization and vaccination dose of inactivated HAdV-55 antigen induced BALB/c mice virus specific IgG antibody was also significantly increased. However, neutralizing antibody can reach detectable level only after enhanced immunity, and the geometric mean titer (GMT) of neutralizing antibody is between 1: 11 and 1: 23. Different adjuvants have significant effects on the immune response of mice. Low dose antigen combined with CPG-ODN and aluminum hydroxide mixed adjuvant can induce higher humoral and cellular immune responses in mice, and the levels of specific IgG antibody and neutralizing antibody are 2.2 and 1.8 times higher than those in the aluminum hydroxide adjuvant group, respectively. The number of lymphocytes secreting IFN-γ was 2.3 times that of the group immunized with aluminum hydroxide adjuvant.Conclusions:The novel CPG-ODN adjuvant significantly increased the immunogenicity of the inactivated HAdV-55 whole virus antigen in BALB/c mice and directed the cellular immune response toward Th1 type.