Objective:To compare the enrichment effects of ultrafiltration, polyethylene glycol (PEG) precipitation, aluminum salt precipitation, and anionic membrane adsorption-elution on viruses in drinking water.Methods:Using phage MS2 as the target virus, three different concentrations of drinking water samples were prepared, and the samples were enriched by ultrafiltration 1, ultrafiltration 2, PEG precipitation, aluminum salt precipitation, and anionic membrane adsorption-elution method, respectively. Real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to quantify MS2 nucleic acid in pre and post concentrated samples and the recovery rates of MS2 in samples with high, medium and low concentrations were compared among the five methods.Results:Comparing the MS2 enrichment recovery rates of individual enrichment method in water samples of different concentrations, ultrafiltration method 1, PEG precipitation method, aluminum salt precipitation method, and membrane adsorption-elution method were not affected by the sample concentration, and the differences of the recovery rates for the three concentration water samples among the four methods were not statistically significant ( P>0.05). The MS2 enrichment recovery rates of the five enrichment methods were significantly different in all concentration samples ( P<0.05). The recovery rates of ultrafiltration method 1 were higher in all three concentration samples, followed by aluminum salt precipitation and anionic membrane adsorption-elution, PEG precipitation were higher in high concentration samples, but lower in low and medium concentration samples, and the recovery rates of ultrafiltration method 2 were the lowest in all three concentration samples. Comparing the Ct values of MS2 in the enriched samples by five methods, the Ct values of ultrafiltration method 1 were the smallest in the three concentration water samples. There was no statistically significant difference in MS2 Ct values among the five enrichment methods in the medium and high concentration water samples ( P>0.05). In low concentration simulated water samples, only the difference of MS2 Ct value between ultrafiltration method 1 and ultrafiltration method 2 was statistically significant ( Z=16.000, P=0.016). Conclusions:Considering the operation simplicity, operation time and virus recovery rate after enrichment, ultrafiltration was the most effective method for virus enrichment in drinking water.

Objective:To evaluate the preservation efficacy of 7 non-inactivating virus preservation solutions.Methods:Equal amounts of H1N1 virus were added to 7 commercially available non-inactivating virus preservation solutions, and the samples were stored at -20 ℃, 4 ℃, 25 ℃ and 37 ℃ for 1 hour, 6 hours, 1 day, 3 days, and 5 days. The viral nucleic acid in each simulated sample under different storage conditions was measured using real-time quantitative PCR. The hemagglutination (HA) titer was determined through viral isolation culture and hemagglutination assay, comparing the differences in viral growth activity across different storage solutions and conditions.Results:Except for solution E, the other solutions effectively protected viral nucleic acid at the 4 storage temperatures. In terms of viral activity, solutions A, B, C, and D effectively maintained viral viability. A and B showing the best performance, E and F showed poorer performance, and G performed the worst.Conclusions:Most non-inactivating virus preservation solutions effectively protect viral nucleic acid, but there are significant differences in their ability to maintain viral viability. To ensure optimal virus preservation, it is recommended that medical institutions evaluate the effectiveness of preservation solutions before use.

Objectives:To explore the predictive value of residual Murray's law-based quantitative flow ratio(μQFR)on long-term vessel-oriented composite endpoints(VoCE).Methods:This retrospective study included 3 510 patients from the FAVOR Ⅲ China trial.Offline residual μQFR analysis was performed on all vessels(diameter≥2.5 mm)with 50%-90%stenotic lesions.Patients were stratified into high-,intermediate-,and low-risk groups based on residual μQFR tertiles.The primary endpoint was 3-year VoCE,defined as a composite of cardiac death related to the target vessel,target vessel-related spontaneous myocardial infarction,and ischemia-driven target vessel revascularization.Results:Offline analysis was performed on 5 256 vessels from 3 510 patients.The mean residual μQFR was 0.92±0.75.The high-risk group(residual μQFR≤0.91)with 1 554 patients(1 958 vessels);the intermediate-risk group(residual μQFR 0.92-0.96)with 1 211 patients(1 906 vessels);and the low-risk group(residual μQFR>0.96)with 745 patients(1 392 vessels).Over 3-year follow-up,VoCE occurred in 227 vessels(4.3%).The 3-year VoCE incidence was significantly higher in the high-risk group compared to the intermediate-and low-risk groups(6.2%vs.4.1%vs.2.5%,log-rank P<0.001),primarily driven by ischemia-driven target vessel revascularization(5.0%vs.3.0%vs.1.6%,log-rank P<0.001).Hypertension(OR=0.83,95%CI:0.72-0.96),hypercholesterolemia(OR=0.84,95%CI:0.73-0.97),bifurcation lesions(OR=0.72,95%CI:0.63-0.83),moderate/severe calcification(OR=0.70,95%CI:0.57-0.84),and tandem lesions(OR=0.59,95%CI:0.47-0.75)were independent predictors of lower residual μQFR values.Conclusions:Lower residual μQFR is significantly associated with increased VoCE risk during the 3-year follow up period.

Objectives:To explore the predictive value of residual Murray's law-based quantitative flow ratio(μQFR)on long-term vessel-oriented composite endpoints(VoCE).Methods:This retrospective study included 3 510 patients from the FAVOR Ⅲ China trial.Offline residual μQFR analysis was performed on all vessels(diameter≥2.5 mm)with 50%-90%stenotic lesions.Patients were stratified into high-,intermediate-,and low-risk groups based on residual μQFR tertiles.The primary endpoint was 3-year VoCE,defined as a composite of cardiac death related to the target vessel,target vessel-related spontaneous myocardial infarction,and ischemia-driven target vessel revascularization.Results:Offline analysis was performed on 5 256 vessels from 3 510 patients.The mean residual μQFR was 0.92±0.75.The high-risk group(residual μQFR≤0.91)with 1 554 patients(1 958 vessels);the intermediate-risk group(residual μQFR 0.92-0.96)with 1 211 patients(1 906 vessels);and the low-risk group(residual μQFR>0.96)with 745 patients(1 392 vessels).Over 3-year follow-up,VoCE occurred in 227 vessels(4.3%).The 3-year VoCE incidence was significantly higher in the high-risk group compared to the intermediate-and low-risk groups(6.2%vs.4.1%vs.2.5%,log-rank P<0.001),primarily driven by ischemia-driven target vessel revascularization(5.0%vs.3.0%vs.1.6%,log-rank P<0.001).Hypertension(OR=0.83,95%CI:0.72-0.96),hypercholesterolemia(OR=0.84,95%CI:0.73-0.97),bifurcation lesions(OR=0.72,95%CI:0.63-0.83),moderate/severe calcification(OR=0.70,95%CI:0.57-0.84),and tandem lesions(OR=0.59,95%CI:0.47-0.75)were independent predictors of lower residual μQFR values.Conclusions:Lower residual μQFR is significantly associated with increased VoCE risk during the 3-year follow up period.

Objective:To compare the enrichment effects of ultrafiltration, polyethylene glycol (PEG) precipitation, aluminum salt precipitation, and anionic membrane adsorption-elution on viruses in drinking water.Methods:Using phage MS2 as the target virus, three different concentrations of drinking water samples were prepared, and the samples were enriched by ultrafiltration 1, ultrafiltration 2, PEG precipitation, aluminum salt precipitation, and anionic membrane adsorption-elution method, respectively. Real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to quantify MS2 nucleic acid in pre and post concentrated samples and the recovery rates of MS2 in samples with high, medium and low concentrations were compared among the five methods.Results:Comparing the MS2 enrichment recovery rates of individual enrichment method in water samples of different concentrations, ultrafiltration method 1, PEG precipitation method, aluminum salt precipitation method, and membrane adsorption-elution method were not affected by the sample concentration, and the differences of the recovery rates for the three concentration water samples among the four methods were not statistically significant ( P>0.05). The MS2 enrichment recovery rates of the five enrichment methods were significantly different in all concentration samples ( P<0.05). The recovery rates of ultrafiltration method 1 were higher in all three concentration samples, followed by aluminum salt precipitation and anionic membrane adsorption-elution, PEG precipitation were higher in high concentration samples, but lower in low and medium concentration samples, and the recovery rates of ultrafiltration method 2 were the lowest in all three concentration samples. Comparing the Ct values of MS2 in the enriched samples by five methods, the Ct values of ultrafiltration method 1 were the smallest in the three concentration water samples. There was no statistically significant difference in MS2 Ct values among the five enrichment methods in the medium and high concentration water samples ( P>0.05). In low concentration simulated water samples, only the difference of MS2 Ct value between ultrafiltration method 1 and ultrafiltration method 2 was statistically significant ( Z=16.000, P=0.016). Conclusions:Considering the operation simplicity, operation time and virus recovery rate after enrichment, ultrafiltration was the most effective method for virus enrichment in drinking water.

Objective:To evaluate the preservation efficacy of 7 non-inactivating virus preservation solutions.Methods:Equal amounts of H1N1 virus were added to 7 commercially available non-inactivating virus preservation solutions, and the samples were stored at -20 ℃, 4 ℃, 25 ℃ and 37 ℃ for 1 hour, 6 hours, 1 day, 3 days, and 5 days. The viral nucleic acid in each simulated sample under different storage conditions was measured using real-time quantitative PCR. The hemagglutination (HA) titer was determined through viral isolation culture and hemagglutination assay, comparing the differences in viral growth activity across different storage solutions and conditions.Results:Except for solution E, the other solutions effectively protected viral nucleic acid at the 4 storage temperatures. In terms of viral activity, solutions A, B, C, and D effectively maintained viral viability. A and B showing the best performance, E and F showed poorer performance, and G performed the worst.Conclusions:Most non-inactivating virus preservation solutions effectively protect viral nucleic acid, but there are significant differences in their ability to maintain viral viability. To ensure optimal virus preservation, it is recommended that medical institutions evaluate the effectiveness of preservation solutions before use.

Objective:To disclose phylogenetic and antigenic characteristics of hemagglutinin (HA) gene of influenza B virus (Victoria) (BV) in the 2023-2024 influenza surveillance season in Beijing, and understand the matching with influenza vaccine component strain.Methods:Pharyngeal swab specimens from influenza like-illness (ILI) in the 2023-2024 influenza surveillance season were collected from surveillance network labs in Beijing and BV strains were isolated through MDCK or chicken embryo culture. After extracting nucleic acid, HA gene was amplified and sequenced. The nucleotide and amino acid sequence identity were conducted and the maximum likelihood method in Mega 5.0 software was used to construct the phylogenetic tree of HA gene. N-glycosylation sites of HA were performed online. Furthermore, three-dimensional structure of HA was available from SWISS-MODEL homologous modeling. Hemagglutination inhibition (HI) tests were performed to analyze antigenic characteristics of HA of BV strains.Results:Fifty-four BV strains were randomly selected to be analyzed further. Compared with the HA gene of this influenza season vaccine strain (B/Austria/1359417/2021), there are three amino acid mutations among all BV strains, two of which are located in two different antigenic determinants. Furthermore, the phylogenetic tree analysis revealed that only one subgroup of 1A.3a.2 was circulating simultaneously. All BV strains are located in Clade 1A.3a.2 subgroup, and in the same subgroup with that of the vaccine component BV strain in 2023-2024. All BV strains have the same glycosylation sites as that of the vaccine component BV strain in 2023-2024. Antigenic analysis showed that all BV strains were antigenically similar with its vaccine strain.Conclusions:In the 2023-2024 influenza surveillance season, the prevalent BV strains in the population in Beijing city are located in Clade 1A. 3a. 2 subgroup. The antigen matching between BV epidemic strains and vaccine BV components is relatively high during this surveillance season.

Objective:To investigate the phylogenetic and antigenic characteristics of hemagglutinin (HA) gene of influenza B/Victoria lineage (BV) viruses in Beijing during the 2021-2022 influenza surveillance season, and to analyze whether the circulating BV viruses match the vaccine strain.Methods:Pharyngeal swab specimens from influenza like-illness (ILI) cases in the 2021-2022 influenza surveillance season were collected from surveillance network labs in Beijing and cultured in MDCK cells and chicken embryo to isolate BV viruses. Nucleic acids of the viruses were extracted, and the HA gene was amplified and sequenced. The nucleotide and amino acid sequence identity of the HA gene was analyzed using MEGA5.0 software. A phylogenetic tree of HA gene was constructed using the maximum likelihood method. The N-glycosylation sites in HA were predicted online. Three-dimensional structure of HA was constructed using SWISS-MODEL homologous modeling. Hemagglutination inhibition (HI) test was performed to analyze the antigenicity of BV viruses.Results:A total of 402 BV viruses were collected and 58 strains with full-length HA gene sequences were chosen for further analysis. Compared with the HA gene of this year′s vaccine strain (B/Washington/02/2019), there were 27 amino acid mutations, 11 of which were located in four different antigenic determinants. The phylogenetic analysis revealed that three subgroups of 1A.3, 1A.3a1, and 1A.3a2 co-circulated in Beijing with 54 strains (54/58, 93.10%) clustered to the Clade 1A.3a2, two strains (2/58, 3.45%) clustered to the Clade 1A.3a1, and two strains (2/58, 3.45%) in the same subgroup (Clade 1A.3) as the vaccine component BV strain in 2021-2022. Compared with the vaccine strain (B/Washington/02/2019), two BV strains had an additional N-glycosylation site at residue 197, while the other 56 strains showed no change in N-glycosylation sites. Antigenic analysis showed that 35 BV strains (35/58, 60.34%) were antigenically similar to the vaccine strain and 23 strains (23/58, 39.66%) were low-response strains.Conclusions:Three subgroups of BV viruses co-circulated in Beijing during the 2021-2022 influenza surveillance season. The predominant subgroup was Clade 1A.3a2 (93.10%), showing a certain genetic distance with the vaccine strain (B/Washington/02/2019). Nearly 40% (39.66%) of the viruses were low-response strains. This study indicated that continuous monitoring of the variations of influenza epidemic strains and timely providing laboratory basis for screening vaccine component strains were the basic technical guarantee for coping with influenza pandemic.

Objective:To understand the epidemic situation of Redondoviridae in Beijing and analyze its epidemiologic characteristics.Methods:Pharyngeal swab samples of healthy people and patients with acute respiratory infection in Beijing, including influenza like cases and severe acute respiratory infection (SARI) cases in hospitals were collected. Real time PCR was used to detect the nucleic acid of Redondoviridae. The positive samples were amplified and sequenced to analyze their species. The age and sex distribution of patients and species distribution of Redondoviridae were obtained through statistical analysis. Multiplex PCR was used to detect other common respiratory pathogens in the positive samples of Redondoviridae in influenza like cases and SARI cases, and the pathogenicity of Redondoviridae was analyzed.Results:The positive rates of Redondoviridae in healthy people and acute respiratory infection cases were 20.48% (189/923) and 11.23% (43/390), respectively, with a statistically significant difference ( P<0.05). The positive rate of male was higher than that of female in the healthy population, and the positive rate of the elderly group was higher than that of the adult group and the underage group, with a statistically significant difference ( P<0.05). The positive rate of male patients with acute respiratory tract infection was higher than that of female patients, but there was no significant difference. The proportion of Vientovirus in the positive samples of Redondoviridae was higher than that of Brisavirus, and the difference was statistically significant ( P<0.05). Among the throat swabs of respiratory tract infection cases, 43 were positive for Redondoviridae, of whom 24 were not detected for other pathogens. Conclusions:Redondoviridae widely exists in healthy people of all age groups in Beijing, and is also found in acute respiratory infection cases. The positive rate of Redondoviridae is different in different ages and genders. Both Vientovirus and Brisavirus were detected, and the proportion of Vientovirus was significantly higher than Brisavirus.

Objective:To characterize the epidemic of influenza in Beijing from 2022 to 2023 and the variation of gene and antigenicity of hemagglutinin (HA) of influenza A H3N2 virus, so as to provide scientific basis for influenza prevention and control in Beijing.Methods:Statistical analysis was carried out on the result of influenza pathogenic monitoring in Beijing from week 14, 2022 to week 20, 2023, and 79 strains of influenza A H3N2 virus were selected at different time and population sources, and their genetic variation and evolution characteristics were analyzed through HA gene amplification sequencing and antigenicity analysis.Results:From week 14, 2022 to week 20, 2023, 24 244 throat swabs of influenza like cases were collected in Beijing, and 4 987 influenza virus nucleic acid positive cases were detected, including 2 749 influenza A H3N2 positive cases, with a detection rate of 11.34%. Among the 79 strains, 50 strains (63.29%) showed low response, 94.44% of the strains from August to November 2022 had low response, and 54.10% of the strains from February to March 2023 had low response, with a statistically significant difference ( χ2=8.079, P=0.004). Compared with the vaccine strain A/Darwin/9/2021, the HA gene sequence of 79 strains of influenza A H3N2 showed nucleotide similarity of 97.47% to 98.47% and amino acid similarity of 97.05% to 98.17%. Genetic evolution analysis showed that the 18 strains isolated from August to November 2022 were all distributed in the 3C.2a1b.2a.1a.1 branch, while the 61 strains isolated from February to March 2023 all belonged to the 3C.2a1b.2a.3a.1 branch. Compared with the vaccine strain, there were multiple site mutations distributed at multiple antigenic determinants and receptor binding sites in A, B, C, D, and E. All strains had potential glycosylation sites of 8NST, 22NGT, 38NAT, 45NSS, 63NCT, 126NWT, 133NGT, 246NST, 285NGS, 483NET, while one strain missed 165NVT glycosylation sites; 55 strains between February and March 2023 missed 122NES glycosylation sites. Conclusions:The HA gene locus of influenza A H3N2 virus detected in Beijing from week 14, 2022 to week 20, 2023 showed multiple mutations, continuous monitoring of this subtype variation is crucial.