Human Bocavirus 1 (HBoV1) is one major pathogen that has been associated with wheezing illnesses. However, there is still a lack of effective clinical predictive indicators for wheezing illnesses in children infected with HBoV1. A retrospective cohort study was conducted among pediatric patients with single-HBoV1 infection from September 2016 to August 2023. Then, univariate logistic regression was used to screen potential predictors for wheezing illness, and Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to minimize overfitting and select key predictors. Finally, a multivariate logistic regression model was constructed in a training dataset comprising 80% of patients and validated in an independent test dataset comprising 20% of patients. Then, its performance was evaluated using the Area Under the Curve (AUC). A total of 330 pediatric patients were enrolled, including 228 in the wheezing-illness group and 102 in the non-wheezing group. Three independent predictors, including abnormal NK cell percentage (OR = 1.101, 95 %CI 1.03-1.27), preterm birth (OR = 1.65, 95 %CI 1.49-1.82) and personal history of allergy (OR = 1.25, 95 %CI 1.11-1.41), were identified. The model achieved AUCs of 0.904 and 0.876 in the training and test sets, respectively. Using a Youden-derived threshold (0.382), the high-risk group in the test set had an observed wheezing rate of 85.3%, compared with 18.7% in the low-risk group (p < 0.001). Calibration was satisfactory (Hosmer-Lemeshow p = 0.324 and 0.576). A validated predictive model incorporating abnormal NK cell percentage, preterm birth and personal history of allergy accurately stratifies the risk of wheezing illness after HBoV1 infection in children, facilitating early clinical intervention.

The performances of two commercial human adenoviruses (HAdVs) typing kits were evaluated in pediatric patients with acute respiratory tract infections (ARIs). Respiratory specimens were collected from March to December 2023 for HAdV screening by a multiple real-time quantitative polymerase chain reaction kit (M-qPCR). Using sequence-based HAdV typing as the reference method, the performances of one capillary electrophoresis-based multiplex PCR (CEMP) typing kit (HEALTH) for 12 types of HAdVs and one qPCR typing kit (Uninovo) for 7 types of HAdVs were evaluated. Among 267 specimens positive for HAdVs determined by M-qPCR, there were 215 (80.5%, 215/267) in sequence-based HAdV typing, 216 (80.9%, 216/267) in HAdV-CEMP (HEALTH) and 125 (46.8%, 125/267) in HAdV-qPCR (Uninovo) positive for HAdVs. Though both kits showed strong agreements in HAdV-B3 typing with Kappa value > 0.95, the emerging recombinant P7H3F3 was misidentified as B3 or negative by two kits. Most specimens with high cycle threshold (Ct) value identified as HAdV-C2 and HAdV-C5 by HAdV-CEMP (HEALTH) showed negative typing results in sequence-based HAdV typing. Meanwhile, the recombinants of HAdV-C89 [Px2/H2/F2], HAdV-C108 [Px1ps1/H2/F2], Px1ps3H5F5, and Px2H5F5 identified by sequence-based HAdV typing were misidentified as HAdV-C2 and HAdV-C5 by HAdV-CEMP (HEALTH). In conclusion, the HAdV-CEMP (HEALTH) offered a broad spectrum of HAdVs species and high sensitivity in the detection of species C, and the HAdV-qPCR (Uninovo) provided reliable results for the detection of HAdV-B3. Both of them cannot identify recombinant events.

Objective:LLC-MK2/TMPRSS2 cells constitutively express TMPRSS2, eliminating the requirement for additional trypsin during HPIV3 culture. The efficiency of LLC-MK2/TMPRSS2 for isolating HPIV3 from respiratory specimens was evaluated in comparison with Madin-Darby Canine Kidney (MDCK). Methods:HPIV3-positive respiratory specimens from children with acute respiratory infections (February-June 2025) were inoculated into LLC-MK2/TMPRSS2 and MDCK. The cytopathic effect (CPE) was monitored microscopically, and the proportion of positive cells was evaluated using direct immunofluorescence assay (DFA). Viral infection dynamics were assessed using the cycle threshold (Ct) values obtained by qPCR. Results:Among 50 specimens, 35 strains (35/50, 70%) were successfully isolated using LLC-MK2/TMPRSS2, while 14 strains were isolated using MDCK (14/50, 28%). More pronounced CPE and a higher number of virus-infected positive cells were shown in LLC-MK2/TMPRSS2 compared to that in MDCK ( P < 0.001 and P = 0.001, respectively). Among specimens with an initial Ct < 27, the isolation rate of LLC-MK2/TMPRSS2 was higher and the Ct values were lower (< 27) (82.6%, 19/23). Among specimens with an initial Ct of 23 ≤ Ct < 27, the number of specimens with a supernatant Ct ≥ 27 (63.6%, 7/11) was significantly less than that in MDCK ( P = 0.003). Conclusion:LLC-MK2/TMPRSS2 exhibits superior adaptability and replication efficiency in the isolation of HPIV3 from respiratory specimens.

Background: Four genotypes of human bocaviruses (HBoVs) have been identified, with only HBoV1 being detected in respiratory specimens, and with HBoV2 being the predominant human bocavirus in fecal specimens, which implies different tissue tropisms for HBoV1 and HBoV2. It is vital to determine the factors that influence the tissue tropisms. Methods: The major capsid proteins VP3 of HBoV1 and HBoV2 were expressed in eukaryotic cells. Then co-immunoprecipitation (Co-IP) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) (IP-MS) was employed, along with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, to screen host proteins interacting with VP3 of different genotypes. Subsequently, in vitro pull-down assays were conducted to verify the direct virus-host interaction proteins with VP3. Furthermore, molecular docking was performed to predict the interaction interfaces between viral and host proteins. Results: Through IP-MS and enrichment analyses, 50 host proteins that displayed ≥10-fold differential binding affinities between HBoV1 VP3 and HBoV2 VP3 were identified. Among these, seven were considered as high-confidence candidate interactors. Notably, SPLUNC1 and VAMP8 showed predominant expression in respiratory and intestinal tissues, respectively. Subsequent in vitro pull-down assays confirmed that SPLUNC1 specifically bound to HBoV1 VP3, whereas VAMP8 specifically interacted with HBoV2 VP3. Molecular docking analysis further revealed that the binding between SPLUNC1 with HBoV1 VP3, as well as VAMP8 with HBoV2 VP3, was stabilized by extensive hydrophobic interfaces along with specific hydrogen bonds. Conclusions: The specific interactions of host proteins SPLUNC1 with HBoV1 VP3 and VAMP8 with HBoV2 VP3, respectively, provided fundamental evidence that the distinct tissue tropisms of HBoVs may be governed by specific host factors.

The increased circulation of enteroviruses (EVs) from July to December 2024 necessitated a retrospective analysis of hospitalized children with acute respiratory infections in Beijing, China, during 2017-2024. Among the 155 cases confirmed as EVs (0.67%, 155/23,245), with peaks in a triennial pattern and predominance between July and October, 114 were EV-D68, with 82 (71.93%) detected between July and October 2024. Among the 79 VP1 gene sequences of EV-D68 classified into subclades B3 (50.63%, 40/79) and D1 (49.37%, 39/79) through phylogenetic analysis, 31 (77.50%, 31/40) were B3 from 2024, and 34 (87.18%, 34/39) were D1 from 2024. More patients infected with B3 required oxygen supplementation than those infected with D1 (p = 0.042). Therefore, an epidemic of EV-D68 with the co-circulation of B3 and D1 was observed in 2024, with more severe disease caused by B3 than by D1, which underscores the urgent need for surveillance of EV-D68.

Coxsackievirus A4 (CVA4) is an enterovirus associated with diverse clinical syndromes, yet its global evolution and transmission dynamics remain poorly defined. This study aimed to characterize the molecular epidemiology, evolutionary history, and phylodynamic patterns of CVA4 at both local and global scales. In 2024, 34 CVA4 infections were identified during a localized herpangina outbreak in Beijing, primarily affecting children under 5 years of age, with a pronounced peak in July. High detection and isolation rates, together with temporal clustering in mid-2024, indicate a genuine short-term expansion rather than sporadic detection. Phylogenetic analysis of global VP1 sequences resolved six genotypes (A-F), with Beijing strains clustering within genotype E and subgenotype F2, reflecting ongoing worldwide circulation. Bayesian phylodynamic analysis estimated a VP1 evolutionary rate of 1.626 × 10-3 substitutions per site per year (95% highest probability density [HPD], 1.428-1.827 × 10-3) and dated the CVA4 time to the most recent common ancestor back to March 1917 (95% HPD, June 1908-April 1926). Demographic reconstruction revealed fluctuating genetic diversity, with notable expansions in 2013 and 2016, as well as a modest increase in 2023 preceding the outbreak. Phylogeographic analyses identified France and China as key seeding regions. Recombination in the P2 and P3 regions, including evidence of CVA2-related donors, highlights recombination as a major contributor to CVA4 diversity. These findings improve our understanding of CVA4 evolution and transmission and underscore the need for enhanced genomic surveillance.

It has been reported that chronic infection of human norovirus (HuNoV) may potentially serve as a reservoir for viral variants with the possibility to evade population immunity or alter the binding sites of HBGA receptors. In this study, a child diagnosed with Burkitt lymphoma and positive for HuNoV determined by real-time PCR (qPCR) firstly in 15 August 2016, was followed up until 20 March 2018, and 26 fecal specimens and one vomitus were collected to trace the evolutionary characteristics of HuNoV by phylogenetic analysis, meta-genomics next-generation sequencing (mNGS), and temporal evolutionary analysis of VP1 among 23 specimens positive for HuNoV. There were 15 specimens with partial RdRp gene sequences forming an independent cluster with sequences of GII.P31, 14 with the region C sequences and 11 with P domain sequences of VP1 gene clustered together with HuNoV GII.4 Sydney_2012. All these sequences showed that mutations accumulated nearly in a time order, and more mutations were shown in the key epitopes A-E or near the binding sites for HBGA in subdomain P2 with higher evolutionary rates. Analysis of NGS data identified intra-host viral quasi-species, and two genome sequences of the same length from mNGS were assembled from N705, with mutations located in the region of subdomain P2 (1171 nt-1202 nt) which led to five amino acid mutations. In conclusion, the accumulated mutations of HuNoV, especially in subdomain P2, were explored in a child with Burkitt lymphoma, and the sequencing of HuNoV from immunocompromised individuals was proven critical for monitoring intra-host quasi-species evolution and potential variant emergence, providing basic data for clinical infection control.

Background Human bocavirus 1 (HBoV1) causes acute respiratory infections (ARIs) in children, but its diagnosis is complicated by prolonged viral shedding. There are indications that the detection of a circular genome in a clinical specimens may be associated with acute infection. Methods Respiratory specimens collected from pediatric patients with ARIs during January 2021 to July 2024 were screened by a duplex qPCR, which was developed to distinguish circular genome from total viral genomes and evaluated by nested PCR and antigen test. Clinical data were collected from patients with single HBoV1 infection to reveal the association of circular genome with ARIs and the severity of pneumonia. Results Among 520 specimens positive for HBoV1 DNA, 206 (39.61%) were positive for circular genomes as determined by duplex qPCR, with the median load of total genomes 1010.08 (IQR 109.26, 1010.62) copies/mL significantly higher than 107.81 (IQR 106.88, 108.60) copies/mL in the circular genome negative group (p < 0.0001). In the antigen-positive group, the positive rate for circular genomes was 78.57% (44/56), significantly higher than 34.29% (108/315) observed in the antigen-negative group. Among patients single positive for HBoV1, the circular genome-positive group (n=106) showed more severe clinical manifestations and required more intensive treatment. Logistic regression analysis identified the circular genome as a strong independent risk factor for severe pneumonia (OR = 6.38, AUC = 0.82). Conclusion Circular genome of HBoV1 associated with high load of viral DNA, positive antigen and severe pneumonia in children may serve as a biomarker for acute HBoV1 infection and severe pneumonia.

Introduction:Coxsackievirus A12 (CVA12) is a serotype of Enterovirus A. Its evolutionary and molecular characteristics remain poorly understood. Methods:The metagenomic Next-Generation Sequencing (mNGS) strategy were used to investigate the viral diversity. The viral isolation, proliferation assays, phylogenetic relationships and recombination events were analyzed. Results:In this study, nine clinical specimens collected in Beijing, China, during March 2010 to October 2019 were identified as CVA12 positive, among which five were confirmed by mNGS. Then five CVA12 strains were isolated, and the proliferation assays demonstrated the preferential replication of CVA12 in rhabdomyosarcoma (RD) cells, with rapid intracellular replication before being released extracellularly, over Hep-2 cells. Transcriptomic profiling of infected RD cells revealed that the significant up-regulated genes were involved in inflammatory responses and transcriptional regulation (e.g., JUN, FOS), suggesting robust host immune activation. Phylogenetic analysis identified that four strains were clustered into genogroup E, indicating a lineage undergoing active transmission in Beijing, China, the other one into genogroups B. Recombination analysis revealed that strain s7275 exhibited recombination with CVA5 (strain 3,490, GenBank access number OK334538) at the breakpoint position 3,373-6,634, while the others showed recombination with EV-A71 (strain EV71/P1034/2013/China, GenBank access number KP289419) at breakpoint position 3,370-6,645. Discussion:These findings underscored the genetic diversity and recombination dynamics which provided insights into the evolutionary implications of CVA12, and its proliferation features in RD cells of CVA12. Further research is needed to elucidate the functional mechanisms of CVA12 infection and its role for disease.

ABSTRACT Human bocavirus (HBoVs) is an emerging virus globally, and its prevalence, diversity, and evolution in children with acute gastroenteritis require further study. Fecal specimens collected from outpatients with acute gastroenteritis in Beijing, China, from April 2014 to December 2023, were tested for HBoVs by PCR targeting the NS1 gene. Genotyping was based on the NP1/VP1 boundary region, and nearly full-length HBoV2 sequences were analyzed phylogenetically. A total of 79 HBoVs-positive specimens (2.5%, 79/3,116, 95% CI: 2.0%–3.1%) were detected, with HBoV2 (65.8%, 52/79, 95% CI: 55.4%–76.3%) as the dominant genotype, followed by HBoV1 (25.3%, 20/79, 95% CI: 15.7%–34.9%) and HBoV3 (8.9%, 7/79, 95% CI: 2.6%–15.1%). HBoVs were distributed throughout the year, with higher positive rates observed from August to December 2018–2021. They predominantly infected children younger than 5 years, especially those aged 6–24 months (3.3%, 52/1,591, 95% CI: 2.4%–4.1%). HBoV2C was the prevalent sub-genotype in Beijing. Novel recombination events were detected between HBoV2 sub-genotypes, with breakpoints in the NS1 and VP3 gene regions. Evolutionary analysis estimated the time to the most recent common ancestor (tMRCA) for HBoV2 dating back to 1845, with a mean nucleotide substitution rate of 1.4 × 10−4 substitutions/site/year, and that HBoV2A evolved faster than HBoV2C. The evolutionary rates decreased in the following order: NP1, VP3, VP1, and NS1. A purifying selection was observed on HBoV2 genes, with one positively selected site in the NS1 gene. In conclusion, HBoV2 was the dominant genotype in children with acute gastroenteritis in Beijing, China, with higher susceptibility in those under 2 years old. Novel recombination events between HBoV2 sub-genotypes occurred frequently.IMPORTANCEAcute gastroenteritis remains a leading cause of morbidity and mortality in children, with viral infections being the primary causative agents. In this study, we investigated the prevalence of human bocavirus (HBoVs) in children with acute gastroenteritis in Beijing from 2014 to 2023, identifying HBoV2C as the predominant sub-genotype. Additionally, this study reported the first estimate of the evolutionary rate for global HBoV2 (1.4 × 10−4 substitutions/site/year) and identified novel intra-genotype recombination events in HBoV2. The results not only filled a gap in the evolutionary studies of global HBoV2 but also offered valuable data for the development of effective surveillance and prevention strategies for controlling acute gastroenteritis in children.

The risk factors of severe infections in children during the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) outbreak in Beijing remain elusive. SARS‐CoV‐2‐positive children admitted to the intensive care unit (ICU) with collected plasma specimens were enrolled and screened for common pathogens using capillary electrophoresis‐based multiplex PCR from December 12, 2022, to January 24, 2023. The SARS‐CoV‐2 subvariants were identified using next‐generation sequencing. Plasma was positive for two (positive; P), one (suspicious; S), or no (negative; N) SARS‐CoV‐2 genes were classified as plasmatic RNA‐positive (RNAemia; P + S) or without RNAemia (N). Clinical and laboratory data of the enrolled cases were then collected and analyzed. The 34 enrolled children included 26 males and 24 younger than three years. All were negative for other respiratory pathogens. BF.7.14 (18/29) was the predominant subvariant. Viral loads in respiratory specimens, hours from symptom onset to the first respiratory specimen collection (time‐variable), with comorbidities and BF.7.14 and BA.5.2 distributions were significantly different in P vs. N and RNAemia vs. without RNAemia group. Among most cases, the T lymphocyte ratios decreased, while the cytokine level and the B lymphocyte ratio increased. The time variables were 2.22 ± 2.05 and 4.00 ± 2.49 days in BF.7.14 and BA.5.2 infections, respectively. In conclusion, SARS‐CoV‐2 was more likely to cause severe infections among males aged ≤ 3 years old with comorbidities during the SARS‐CoV‐2 outbreak in Beijing, while RNAemia is more common in children at the early stage of severe BF.7.14 infections, and most had high cytokine levels and B‐cell activation.

Head-to-tail sequences have been reported in human bocavirus (HBoV) 1-4. To reveal their features and functions, HBoV DNA was screened among respiratory specimens from pediatric patients with an acute respiratory infection (ARI) between April 2020 and December 2022, followed by HBoV genotyping. Head-to-tail sequences were detected using nested PCR, TA cloning, and Sanger sequencing, and these findings were confirmed by mNGS and amplicon sequencing. The secondary structure was predicted using the Mfold web server. The results indicated that head-to-tail sequences were detected in 42 specimens through TA cloning from 351 specimens positive for HBoV1 DNA, yielding 92 sequences into 32 types and 2 categories. Additionally, head-to-tail sequences were detected in 16 specimens by amplicon sequencing, yielding 60 sequences categorized into 23 types. The 374nt type, detected in 13 specimens, contains variants 374a and 374b, which differ in the unpaired loop regions of the palindrome or complementary reverse sequences, implying a switch of template chains during the replication process. The mNGS results in three specimens confirmed the presence of circular genome in copies below 1%. In conclusion, head-to-tail sequences of HBoV1 were common in children with ARI and were highly diverse in length and sequences. The variants may be generated by the switch of the template chain in the rolling-circle replication model.

BACKGROUND:Previous serological studies of human bocavirus (HBoV) 1 could not exclude cross-reactivity with the other three HBoVs, particularly HBoV2.METHODS:To search for genotype-specific antibodies against HBoV1 and HBoV2, the divergent regions (DRs) located on the major capsid protein VP3 were defined through viral amino acid alignment and structure prediction. DR-deduced peptides were used as antigens to harvest corresponding anti-DR rabbit sera. To determine their genotype specificities for HBoV1 and HBoV2, these sera samples were used as antibodies against the antigens VP3 of HBoV1 and HBoV2 (expressed in Escherichia coli) in western blotting (WB), enzyme-linked immunosorbent assay (ELISA), and bio-layer interferometry (BLI) assays. Subsequently, the antibodies were evaluated with clinical specimens from pediatric patients with acute respiratory tract infection by indirect immunofluorescence assay (IFA).RESULTS:There were four DRs (DR1-4) located on VP3 with different secondary and tertiary structures between HBoV1 and HBoV2. Regarding the reactivity with VP3 of HBoV1 or HBoV2 in WB and ELISA, high intra-genotype cross-reactivity of anti-HBoV1 or HBoV2 DR1, DR3, and DR4, but not anti-DR2, was observed. Genotype-specific binding capacity of anti-DR2 sera was confirmed by BLI and IFA, in which only anti-HBoV1 DR2 antibody reacted with HBoV1-positive respiratory specimens.CONCLUSION:Antibodies against DR2, located on VP3 of HBoV1 or HBoV2, were genotype specific for HBoV1 and HBoV2, respectively.

Our previous surveillance revealed that t203-like G9 (tentatively designated subtype G9-VI) rotaviruses re-emerged in 2010 in Beijing and rapidly prevailed over the G9-III subtype (the most common G9 subtype globally) and previously predominant G genotypes over the following two years. G9-VI belongs to the VP7 evolutionary lineage VI, which includes unusual and sporadic human rotaviruses from China (t203) and Japan. To obtain insight into the epidemiology, evolution, and transmission advantages of G9-VI rotavirus, we performed follow-up surveillance (2014-2017) and whole-genome analysis of 12 representative G9 strains. The results showed that the G9 genotype was predominant (77.4%), with a marked increase in prevalence (previously 43.5%). Within the G9 genotype, subtype G9-VI accounted for the majority (98.3%) of cases. The most prevalent P-genotype was P[8] (93.7%), within which subtype P[8]b was rare (0.7%). Phylogenetically, the G9-VI subtype strains in this study clustered closely with contemporary emerging human rotaviruses from many other countries in VP7 lineage VI, indicating that this subtype is capable of spreading globally. These currently emerging G9-VI rotaviruses formed a distinct monophyletic subcluster when compared to early G9-VI rotaviruses. Furthermore, four specific amino acid substitutions and synonymous codon substitutions were observed in the VP7 genes between the current G9-VI and globally common G9-III rotaviruses. The remaining nine genes of all of the analyzed representative G9 strains, whether G9-VI or G9-III, combined with the P[8]a, P[8]b, or P[6] genotype and exhibited the same Wa-like backbone constellation.

Human adenovirus serotype 31 (HAdV-31) is closely associated with gastroenteritis in children and can cause fatal systemic disseminated diseases in immunocompromised patients. The lack of genomic data for HAdV-31, especially in China, will greatly limit research on its prevention and control. Sequencing and bioinformatics analyses were performed for HAdV-31 strains from diarrheal children in Beijing, China, during 2010–2022. Three capsid protein genes (hexon, penton, and fiber) were obtained in 37 cases, including one in which the whole genome was sequenced. HAdV-31 strains clustered into three distinct clades (I–III) in a phylogenetic tree constructed based on concatenated genes and the whole genome; the endemic strains only gathered into clade II, and most of the reference strains clustered into clade I. Compared with penton and hexon, fiber had a faster evolutionary rate (1.32 × 10−4 substitutions/site/year), an earlier divergence time (1697), lower homology (98.32–100% at the amino acid level), and greater genetic variation (0.0032). Four out of the six predicted positive selection pressure codons were also in the knob of fiber. These results reveal the molecular evolution characteristics and variations of HAdV-31 in Beijing, and fiber may be one of the main evolution driving forces.

Background The coronavirus disease 2019 outbreak has hit Beijing since mid-Nov, 2022, with soaring growth of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among children. Therefore, it is vital to determine the clinical manifestations of epidemic SARS-CoV-2 strains in paediatric patients. Methods In this study, nucleic acid tests (NATs) for SARS-CoV-2 were performed in paediatric outpatients with symptoms of acute respiratory tract infection during 18 Nov–6 Dec, 2022. Half of the outpatients positive for SARS-CoV-2 were randomly selected to screen for other respiratory pathogens, whereas those with low cycle threshold values in SARS-CoV-2 NATs were amplified and sequenced to determine the SARS-CoV-2 variants. Finally, children positive for SARS-CoV-2 with clinical information in detail were enrolled in a follow-up study to identify potential factors significantly associated with long recovery. Results Among 9625 paediatric outpatients tested for nucleic acid of SARS-CoV-2, 733 (7.62%, 733/9625) were identified as SARS-CoV-2 NAT positive, with only three (0.82%, 3/366) co-infected with other pathogens among 366 randomly selected patients, and 71 (62.83%) determined as Omicron subvariant BF.7 and 42 (37.22%) as BA.5.2 among 113 successfully sequenced. Among the 681 patients with complete clinical information, fever was the most common symptom (96.8%). In a follow-up study of 592 patients, 46.96% became asymptomatic on the third day and 65.71% on the fifth day. Only 1.7% of infected children experienced febrile seizures. Combined with abnormal C-reactive protein, a higher percentage of antibiotics administration was observed. More co-living members and longer duration of first symptoms served as independent risk factors for long-term recovery, especially in children vaccinated for SARS-CoV-2. Conclusions BF.7 and BA.5.2 were the dominate Omicron subvariants and caused milder infections during the SARS-CoV-2 outbreak in Beijing. The number of co-living members and duration of first symptoms were independent risk factors for long-term recovery.

Objective:To understand the characters of norovirus infection in children with acute diarrhea in Beijing from 2014 to 2019.Methods:Fecal specimens were collected from children with acute diarrhea visiting the hospital affiliated to the Capital Institute of Pediatrics from April 2014 to December 2019 for norovirus screening by reverse transcription-polymerase chain reaction (RT-PCR). Then RdRp gene and VP1 gene of norovirus (NoV) were amplified and sequenced from positive specimens and then genotyped by Norovirus Genotyping Tool 2.0.Results:Fecal specimens were collected from 2 577 cases with acute diarrhea and tested for NoV RNA in this study, of which 484 cases (18.78%, 484/2 577) were positive for NoV. NoV infection can occur all year round, with obvious seasonal distribution, the epidemic peak is in autumn and winter. There was no gender difference in the detection of NoV ( χ2=1.77, P=0.183). 399 specimens genotyped by VP1 gene with 98.25% (392/399) being GII and GII.4 Sydney as the mainly genotype (52.13%, 208/399), followed by GII.3 (19.8%, 79/399) and GII.2 (18.5%, 74/399). Then 267 specimens also were genotyped by RdRp region, which revealed that the main genotype was GII.P31 (57.3 %, 153/267), followed by GII.P12 (15.36%, 41/267) and GII.P16 (14.98 %, 40/267). Dual-typing revealed that various combination strains, GII.4 Sydney[P31] (53.18%, 142/267) as the major combination, followed by GII.3[P12] and GII.2[P16] (15.36%, 41/267 and 10.49%, 28/267). While GII.3[P12] showed a downward trend, GII.4 Sydney[P16] increased gradually. Conclusions:Norovirus is an important pathogen of acute diarrhea in children in Beijing, from 2014 to 2019, with various prevalent genotypes.

Human adenovirus serotype 41 (HAdV-F41) is an important pathogen that causes diarrhea in children. However, the data on its molecular genetic characteristics and evolutionary history are still neither comprehensive nor sufficient. Four capsid protein genes from 58 HAdV-F41-positive specimens taken from diarrheal children in Beijing during 2010-2019 were amplified and analyzed. Variant amino acids in the hexon gene (18 sites) and short fiber gene (4 sites) clustered these strains into two clades and four subclades. The deletion of 15 amino acids found in the gene seemed to have little effect on the genomic strain cluster same as to penton gene. The HAdV-F41 strains had high diversity, as assessed from the intraspecific recombination of hexon, short fiber and long fiber. The molecular evolutionary rate of HAdV-F41's concatenated genes was 4.07 x 10(-5) substitutions/ site/year, and it diverged from the most recent common ancestor in 1720. Apart from in the penton gene, positive selection codons were predicted in the other three genes, which may play a synergistic role in the evolution of HAdV-F41. These results provide new insights for understanding the characteristics of infectivity and developing vectors and vaccine vehicles for HAdV-F41.

人腺病毒41型(Human adenovirus 41,HAdV-41)是引起儿童腹泻的重要病原之一.为了解北京地区腹泻儿童中HAdV-41 Fiber基因的分子变异和遗传进化特征,选取2010-2019年首都儿科研究所附属儿童医院门诊腹泻患儿HAdV-41阳性的粪便标本,扩增Fiber全基因,使用多种生物信息学软件进行系统发生、遗传进化、种群演变和选择压力等分析.结果显示HAdV-41本地毒株存在1644碱基(547氨基酸)和1689碱基(562氨基酸)两种长度的Fiber基因,截短的15个氨基酸位于Fiber蛋白纤维轴区.Mann-Whitney U秩和检验提示检测到感染短Fiber基因的HAdV-41的患儿年龄更小(P=0.036).同源性分析结果显示Fiber基因的核苷酸和氨基酸序列同源性均大于97％,主要分为四个进化分支(Ⅰ、Ⅱ、Ⅲ和Ⅳ),其中Ⅰ和Ⅲ是主要的流行分支,分支Ⅰ主要在国内流行,而分支Ⅲ全球均有流行.HAdV-41共祖起源可追溯到1856年,平均进化速率每年为6.81×105碱基替换/位点,10年间理论有效种群一直比较平稳呈缓慢下降趋势.压力选择分析表明,一个正向和三个负向选择位点均位于Fiber蛋白的纤维轴区.上述结果表明2010-2019年间不同进化分支的HAdV-41在北京地区流行,进化速率稳定.Fiber蛋白轴区存在两种不同类型的氨基酸缺失.

目的 建立一个儿童手足口病(H FM D)的临床诊断评分系统,并评价其准确度.方法 回顾性分析2012年1月至2017年12月在首都儿科研究所附属儿童医院感染科就诊的1435例年龄≤3岁的急性出疹性疾病患儿的临床资料,根据肠道病毒核酸检测结果,分为H FM D组1094例和非H FM D组341例.随机选取70％ 作为训练集(1004例),其余30％ 作为测试集(431例),采用多元Logistic回归筛选临床变量并建立手足口病临床诊断评分系统,同时在测试集中进行评分系统的验证及评价.结果 H FM D组病程、年龄、暴露史阳性占比均显著大于非H FM D组(χ2/t值分别为3.36、4.44、97.88,P<0.01),两组性别构成比差异无统计学意义(P>0.05);HFMD组在硬腭、软腭、舌、颊粘膜、牙龈、前胸、后背、臀部和足趾的皮疹分布数量较非H FM D组更多(χ2值分别为61.77、48.25、20.79、41.32、7.73、27.53、30.34、44.23、29.27,P<0.05);H FM D组发热的比例以及白细胞计数和中性粒细胞占比均高于非H FM D组(χ2/t值分别为13.49、5.21、10.17,P<0.05);利用训练集数据共筛选出7项纳入多因素评分预测模型,包括年龄、暴露史、3个口腔溃疡部位(硬腭、软腭、颊粘膜)和2个躯体皮疹部位(背部、臀部),该评分系统受试者工作特征(ROC)曲线下面积为0.80(95％CI:0.77～0.84,P<0.01),敏感度为0.76,特异度为0.68;评分系统在测试集中ROC曲线下面积为0.76(95％CI:0.71～0.81,P<0.01),敏感度为0.76,特异度为0.62.结论 该评分系统敏感度、特异度及准确性较好,可作为一种儿童手足口病快速、低成本的辅助诊断方法.