Infectious diseases seriously endanger human health. Rapid and accurate detection of pathogens is the key to effective treatment and precise prevention and control of infectious diseases. Traditional pathogen testing techniques cover a limited variety of microorganisms, making it difficult to meet clinical needs. Metagenomic Next Generation Sequencing (mNGS) theoretically can simultaneously detect all known gene sequences of pathogens, greatly improving the clinical capacity of diagnosing and treating patients with severe, complicated, rare, and emerging pathogen infections. In the context of individualized health needs, the self-built testing of new technologies in laboratories can continuously improve the level of clinical diagnosis and treatment. Due to the high starting point of research and development and the complex operation process of the mNGS technology platform, this study reaches a consensus on the experimental procedure, assay validation, quality control, and report review of the mNGS-LDT in the fields of clinical testing, infection, critical care, and in vitro diagnosis to ensure the appropriate application of the technology and guarantee patient safety and proposes standardized requirements and suggestions.

Objective:To investigate the epidemiological and clinical characteristics of RSV among patients aged ≥60 years in Beijing from 2015 to 2023.Methods:Based on the respiratory pathogen surveillance system, samples of upper respiratory tract infections (URTI), non-severe community-acquired pneumonia (nsCAP) and severe community-acquired pneumonia (sCAP) among people aged ≥60 years were collected from 28 sentinel hospitals in 16 districts of Beijing from January 2015 to December 2023. Swab samples were collected from URTI within one week, and lower respiratory tract samples from nsCAP and sCAP were collected. Demographic and epidemiological data were also collected. Various respiratory pathogens including RSV were detected.Results:From January 2015 to December 2023, a total of 20 349 cases of acute respiratory infections aged ≥60 years were included, with the RSV-positive rate of 1.54% (313/20 349, 95% CI: 1.39%-1.68%). Among them, the total RSV-positive rates of older people during the pre-pandemic, pandemic, and post-pandemic periods of COVID-19 were 1.59% (207/13 006, 95% CI: 1.38%-1.81%), 0.82% (38/4 650, 95% CI: 0.56%-1.08%) and 2.53% (68/2 693, 95% CI: 1.93%-3.12%), respectively. The difference in RSV-positive rate was statistically significant ( P<0.001). Based on the sampling time of cases, the RSV epidemic season for older people in Beijing was from October to March of the following year, with a peak period in December or January of the following year. In the post COVID-19 pandemic, there were very few RSV-positive cases detected in the elderly from April to June 2023, with only one positive case detected in May and one in June. The RSV-positive rate of older people increased significantly from October to December, reaching 11.75% (51/383) in December. Among 263 RSV-positive cases in the elderly, RSV-A, RSV-B and unclassified type accounted for 43.35% (114/263), 29.28% (77/263) and 27.38% (72/263), respectively. Since 2020, there has been a subtype conversion, with RSV-B being the main focus. Among 197 elderly cases that have complete clinical data, the main symptoms were cough (86.8%, 171/197), sputum (80.2%, 158/197) and fever (73.60%, 145/197). About 24.87% (49/197) of elderly cases experienced complications. The hospitalization mortality rate was 4.57% (9/197), and the hospitalization rate was 78.68% (155/197). The ICU occupancy rate was 1.99% (36/197). The mechanical ventilation usage rate was 13.32% (33/197), and the length of hospital stay [ M ( Q1, Q3)] was 12 (9, 16) days. Conclusion:In Beijing, the RSV infection rate is relatively low during the COVID-19 pandemic, and the prevalence of COVID-19 is relatively high. In 2023, there was no out-of-season outbreak of RSV infection among the elderly. Elderly RSV infection cases have multiple complications, severe diseases, and poor prognosis.

Objective:To establish a Plaque-reduction Neutralization Test (PRNT) for the detection of neutralizing antibody titers of Human Respiratory Syncytial Virus (HRSV) and optimize the conditions for preliminary application.Methods:The CHO expression system was used to produce palivizumab monoclonal antibody (palivizumab) and the influencing factors such as cell type, cell culture duration, fixation and permeabilization protocols, and blocking agents. The reproducibility of the method was verified and its correlation was verified with conventional PRNT. Finally, the optimized PRNT assay was further used to determine neutralizing antibody titers against HRSV subtypes A and B in BALB/c mouse serum (immunized by intramuscular injection of HRSV fusion proteins).Results:Palivizumab was expressed at approximately 50 mg/L. The optimal working conditions for PRNT were as follows: culturing HEp-2 cells for 2 days, fixing with 4% (V/V) paraformaldehyde at room temperature for 15 min followed by 0.2% (V/V) Triton X-100 permeabilization for 15 minutes as the optimal fixation-permeabilization and removing the blocking step. The overall coefficient of variation (CV) for the reproducibility validation of this method was <15%, showing a good linear relationship with the conventional PRNT. The Spearman correlation coefficient r s was 0.983. This method was used to detect neutralizing antibody titers in mouse sera against HRSV subtype A strain long and subtype B strain 9320, and the fusion proteins combined with AlOH and CpG adjuvant induced the highest neutralizing antibody titers in mice. Conclusion:The HRSV neutralizing antibody assay established in this study is rapid, reproducible, high-throughput, and can be used to detect neutralizing antibodies to HRSV subtypes A and B.

Objective:To analyze the epidemiological distribution characteristics, influencing factors, and infection rates of pertussis in the population of Henan Province.Methods:From 2022 to 2023, a cross-sectional survey was conducted to investigate the permanent population in Henan Province. Enzyme-linked immunosorbent assay (ELISA) was used to detect anti-pertussis toxin IgG (PT-IgG), analyze the antibody positivity rate (≥20 IU/ml) and median concentration (MC), and estimate the pertussis infection rate based on PT IgG ≥40 IU/ml. The rank sum test was used to compare antibody levels among groups, and the χ2 test was used to compare antibody positive rates and infection rates among groups. Results:A total of 4 810 research subjects were included in this study. The overall positive rate of PT-IgG was 12.10% and MC was 3.04 (0.35, 10.36) IU/ml. There were significant differences both in positive rates and antibody levels of PT-IgG among different regions or age groups (region positive rate: χ2=134.06, P<0.001, MC: H=337.74, P<0.001; age group positive rate: χ2=45.27, P<0.001, MC: H=134.49, P<0.001). Both the positive rate of PT-IgG (25.26%) and MC (8.01 IU/ml) were the highest within one year after completing a full course of vaccination. There were significant differences in positive rates and antibody levels among people receiving different types of pertussis vaccines (positive rate: χ2=12.38, P=0.006, MC: H=17.93, P<0.001). The antibody positivity rate (35.71%) and MC (8.88 IU/ml) of the people who received cell-free pertussis inactivated poliomyelitis influenza type b (combined) vaccine throughout the course were higher than those who received other types of vaccines. The natural infection rate of pertussis was evaluated for individuals aged≥3 years who had no history of pertussis vaccine immunization within the year prior to sampling. With a high vaccination rate, the estimated infection rate of pertussis in the population was 5 757.22/100 000. The infection rates in the 3-year-old (1 940.16/100 000) and 4-year-old (1 765.68/100 000) populations were at a low level among the entire population, reaching their peak at the age of 6 (12 656.71/100 000). Subsequently, although the infection rate continued to decline, it remained at a high level and peaked again at the age of 40-49 years (8 740.39/100 000). There was a statistically significant difference in the estimated infection rate of pertussis among different age groups ( χ2=53.21, P<0.001). Conclusion:The PT-IgG level of pertussis in the population of Henan Province is generally at a low level. The estimated infection rate of pertussis is much higher than the reported incidence rate. A booster dose of pertussis vaccine is recommended at 6 years old.

Objective:To investigate the effects of wza gene deletion in Klebsiella pneumoniae on capsule formation ability and bacteriophage sensitivity. Methods:The wza deletion mutant strain was constructed through a temperature-sensitive plasmid-mediated homologous recombination. The growth curves of W14 and Δ wza were detected by measuring the optical density OD 600. In order to analyze the effect of gene wza on bacterial capsule formation, wild-type strain W14 and Δ wza mutant strain were detected by transmission electron microscope, and their capsule contents were measured by quantifying the uronic acid contents. The plaque assay was used to detect bacterial sensitivity to bacteriophage in wild-type strain W14 and Δ wza mutant strain. The t test was used to compare whether there were differences in the contents of uronic acid in the capsules of wild-type strain W14 and Δ wza mutant strain. Results:The PCR results revealed that the Δ wza mutant strain was successfully constructed. Compared with wild-type strain W14, the growth curves of Δ wza on the solid plates demonstrated a slightly slower growth. However, no difference in growth was observed among wild-type strain W14 and Δ wza mutant strains in LB broth. The transmission electron microscope results showed that wza gene deletion resulted in the loss of capsule in bacteria. The uronic acid content assay suggested that the capsule content was significantly decreased in Δ wza mutant strain (45.963±2.795) μg/ml compared with wild-type strain W14 (138.800±5.201) μg/ml. There was a statistical difference between the two groups ( t=27.233, P<0.001). The plaque assay indicated that bacteria lost its sensitivity to bacteriophage when gene wza was deleted. Conclusion:Deletion of the wza gene impairs bacterial capsule formation ability and can affect bacterial sensitivity to bacteriophage phiW14.

Objective:To establish an absolute quantitative method for high ethanol-producing klebsiella pneumoniae in a viable non-culturable (VBNC) state. Methods:High ethanol-producing Klebsiella pneumonia was induced to enter the VBNC state and then the ethanol production was evaluated. A PMA-ddPCR method was established to count the copies of live cell genes in the VBNC state of high ethanol-producing Klebsiella pneumoniae using single-copy genes. Further, the sensitivity and adaptability of ddPCR for detecting low-concentration samples were evaluated in VBNC fecal simulation. Results:The lower detection limit of ddPCR for quantitative analysis of high ethanol-producing Klebsiella pneumoniae gradient diluent was 10 times that of qPCR. At low temperature and low nutritional state, high ethanol-producing Klebsiella pneumoniae entered the VBNC state on the 45 th day. The quantitative results of PMA-ddPCR on VBNC state cells were (5.46±0.05) log 10 DNA copies/ml. The ethanol production in the VBNC state was<2.2 mmol/L and the ability to produce ethanol was restored after recovery. The minimum detection limit for ddPCR in fecal simulated samples with VBNC state was 3.2 log 10 DNA copies/ml. Conclusion:The ddPCR detection method for high ethanol-producing Klebsiella pneumoniae with VBNC state has good sensitivity and adaptability, and can be used for the detection of VBNC state cells in clinical samples.

Objective:To investigate the association between visceral adipose tissue (VAT) thickness in early pregnancy and the risk of gestational diabetes mellitus (GDM).Methods:Based on the Qingdao Women and Children Health Cohort, pregnant women in the first trimester (11-13 +6 weeks of gestation) were enrolled in this cohort study between May 2019 and October 2022. The VAT was measured in first trimester and determined as the distance from the inner margin of the rectus abdominis muscle to the anterior wall of the great artery using multi-functional color ultrasound. The 75 g oral glucose tolerance test (OGTT) results were followed up at 24-28 weeks and the participants were divided into GDM group and non-GDM group. The pregnant women were divided into 4 groups according to the VAT quartile. Log-binomial model and linear regression model were used to analyze the association between VAT and GDM/blood glucose. Results:A total of 3 686 pregnant women were included in this study, the mean age of participants was (30.56±4.05) years and 722 were diagnosed with GDM, with an incidence of 19.6%. The log-binomial regression model results showed that compared with VAT thickness Q1 (VAT<14.70 mm), the GDM risk in Q3 (21.65≤VAT≤29.69 mm) and Q4 (VAT ≥29.70 mm) increased by 34% [ RR(95% CI): 1.34 (1.08-1.67)], and 61% [ RR(95% CI): 1.61 (1.30-2.00)], respectively. Among women with gestational age<35 years old, compared with VAT thickness Q1, the risk of GDM increased by 42% in Q3 [ RR(95% CI): 1.42 (1.22-1.65)] and 70% [ RR(95% CI): 1.70 (1.46-1.98)] in Q4, whereas no associations were found in women with gestational age ≥35 years old ( P>0.05). The association between VAT and GDM risk was only found in pregnant women with pre-pregnancy BMI <24.0 kg/m 2, and the GDM risk increased by 57% [ RR(95% CI): 1.57 (1.22-2.04)] in Q3 and 65% [ RR(95% CI): 1.65 (1.24-2.19)] in Q4 compare with Q1. The results of multiple linear regression analysis showed that VAT was positively correlated with fasting blood glucose, 1-hour blood glucose after 75 g OGTT and 2-hours blood glucose after 75 g OGTT (all Pfor trend<0.001). Conclusion:High VAT thickness in early pregnancy is an independent risk factor for GDM, and the GDM risk increases with the raising of VAT depth.

Objective:To investigate the effects and possible mechanisms of caffeic acid phenethyl ester (CAPE) on the replication, amplification, and fibre formation of prions (PrP Sc). Methods:The CCK8 assay was used to detect the cell viability of the prion-infected cell model SMB-S15 after CAPE treatment for 3 days and 7 days and the maximum safe concentration of CAPE for SMB-S15 was obtained. The cells were treated with a concentration within a safe range, and the content of PrP Sc in the cells before and after CAPE treatment was analyzed by western blot. Protein misfolding cycle amplification (PMCA) and western blot were used to assess changes in PrP Sc level in amplification products following CAPE treatment. Real-time-quaking induced conversion assay (RT-QuIC) technology was employed to explore the changes in fibril formation before and after CAPE treatment. The binding affinity between CAPE and murine recombinant full-length prion protein was determined using a molecular interaction assay. Results:CCK8 cell viability assay results demonstrated that treatment with 1 μmol/L CAPE for 3 and 7 days did not exhibit statistically significant differences in cell viability compared to the control group (all P<0.05). However, when the concentration of CAPE exceeded 1 μmol/L, a significant reduction in cell viability was observed in cells treated with CAPE for 3 and 7 days, compared to the control group (all P<0.05). Thus, 1 μmol/L was determined as the maximum safe concentration of CAPE treatment for SMB-S15 cells. The western blot results revealed that treatment with CAPE for both 3 and 7 days led to a detectable reduction in the levels of PrP Sc in SMB-S15 cells (all P<0.05). The products of PMCA experiments were assessed using western blot. The findings revealed a significant decrease in the levels of PrP Sc (relative grey value) in the PMCA amplification products of adapted-strains SMB-S15, 139A, and ME7 following treatment with CAPE, as compared to the control group (all P<0.05). The RT-QuIC experimental results demonstrated a reduction in fibril formation (as indicated by ThT peak values) in CAPE-treated mouse-adapted strains 139A, ME7, and SMB-S15, as well as in SMB-S15 cells infected with prions. Furthermore, CAPE exhibited varying degrees of inhibition towards different seed fibrils formation, with statistically significant differences observed (all P<0.05). Notably, CAPE exhibited a more pronounced inhibitory effect on ME7 seed fibrils. Molecular interaction analyses demonstrated significant binding between CAPE and murine recombinant prion protein, and the association constant was (2.92±0.41)×10 -6 mol/L. Conclusions:CAPE inhibits PrP Sc replication, amplification, and fibril formation in vitro possibly due to specific interactions with the prion protein at the molecular level.

Objective:To investigate the application value of fecal Syndecan-2 (SDC2) gene methylated SDC2 (m SDC2) detection in colorectal cancer (CRC) screening among urban residents in Guangzhou City. Methods:A cross-sectional study was conducted in Shitan Town, Zengcheng District, Guangzhou City from July to December 2022. A community-based screening program for CRC was conducted among residents aged 40-74 years old. m SDC2 detection was employed in the participants, and those with positive results should be recommended to receive colonoscopy examination. The positive rate of m SDC2 detection, colonoscopy compliance rate, detection rate of intestinal lesions and clinicopathological characteristics were observed. The relationship between cycle threshold (CT) value of m SDC2 and intestinal lesions was explored. Further, the cost-effectiveness of screening was evaluated. Results:A total of 8 189 fecal samples were collected from 8 877 participants with the recovery rate of 92.25%. 8 048 qualified samples were enrolled in this study, consisted of 3 182 males (39.54%) and 4 866 females (60.46%), with the average age of 56 years old (40-74 years). The positive rate of m SDC2 detection was 7.99% (643/8 048), and the compliance rate of colonoscopy was 73.10% (470/643). 20 cases (4.25%) of colorectal cancer, 109 cases (23.19%) of advanced adenoma, 145 cases (30.85%) of non-advanced adenoma, 79 cases (16.81%) of polyps were detected. The detection rate of intestinal lesions was 75.11% and indicated significant differences in gender and age. 20 CRCs included 15 of stage 0-I, 4 of stage Ⅱ-Ⅲ and 1 of unknown stage. The CT value of m SDC2 was negatively correlated with the proportion of advanced colorectal neoplasms ( χ2=16.063, P<0.001). The total cost of the screening was 4.339 5 million yuan, the screening benefit was 28.506 2 million yuan, and the benefit-cost ratio was 6.57. Conclusion:The CRC screening strategy of fecal m SDC2 detection combined with colonoscopy has high colonoscopy compliance and detection rate of intestinal lesions, which is conducive to the detection of early CRCs, and has good cost-effectiveness. This study suggests that this method may be applied to the general CRC screening in China and contribute to the prevention of CRC. The CT value of m SDC2 may have a certain suggestion on the malignant degree of intestinal tumors.

Objective:To analyze the current situation of myopia and its related factors among primary school students in a certain district of Beijing City in 2022, and provide a basis for the risk assessment of myopia among primary school students.Method:In June 2022, a cluster sampling method was used to include 376 third-grade students from a primary school in a certain district of Beijing. A questionnaire survey was conducted to collect basic information about students, including eye usage habits, reading and writing postures, and parents′ myopia conditions. The examination of students′ distant visual acuity and refractive status was performed. A multivariate logistic regression model was used to analyze the related factors of myopia occurrence.Results:The age of 376 primary school students was (8.87±0.417) years old, with 48.40% (182) being male. A total of 196 myopia cases were identified, with a myopia rate of 52.13%. The results of the multivariate logistic regression model analysis showed that students who sometimes read while lying down ( OR=2.003, 95% CI: 1.128-3.555), often read while lying down ( OR=18.853, 95% CI: 4.512-78.778), had outdoor activity time less than 120 minutes per day ( OR=4.937, 95% CI: 2.4464-9.892), were engaged in indoor break activities ( OR=4.995, 95% CI: 2.773-8.996), performed eye exercises less than once per day ( OR=8.710, 95% CI: 4.464-16.995), had a reading distance from the book less than 30 cm ( OR=5.098, 95% CI: 2.410-10.787), occasionally maintained a fist distance from the edge of the desk ( OR=1.918, 95% CI: 1.086-3.385), and had high school desks and tables ( OR=5.325, 95% CI: 1.465-19.359) could have a higher risk of myopia occurrence, compared with those who never read while lying down, had outdoor activity time more than 120 minutes per day, maintained outdoor break activities, performed eye exercises more than once per day, had a reading distance from the book more than 30 cm, always maintained a fist distance from the edge of the desk, and had short school desks and tables. Conclusion:The incidence rate of myopia among primary school students in a certain district of Beijing City. in 2022 is relatively high. The occurrence of myopia is related to insufficient outdoor activity time and poor eye usage habits.