Objective:To understand the molecular characteristics of the mutant strain of polymerase basic protein 2 (PB2) gene of influenza A (H1N1pdm) in Guangdong province, and to explore its specific molecular sites, so as to provide scientific basis for the prevention and control of influenza virus.Methods:Throat swab samples were collected from 2 cases infected with PB2 gene variant strains for virus isolation, and 23 influenza virus strains were selected from Guangdong province for sequencing analysis. The reference sequences and vaccine strain sequences provided by GISAID were used to perform evolutionary analysis on hemagglutinin (HA) and PB2 genes. Virus strain antigen analysis and neuraminidase (NA) inhibition test were carried out. PB2 protein model was constructed and polymerase activity was analyzed.Results:H399N amino acid mutation occurred in the HA gene of PB2-D701N and PB2-A271S variant strains, both of which belonged to the branch of 6B.1A.5a.2a. They belonged to the same big branch and different small branches as the vaccine strain A/Victoria/4897/2022, and they are all vaccine-like strains. In the three-dimensional structure, the mutations of PB2-D701N and PB2-A271S change charge and hydrophobicity.Conclusions:PB2-D701 and A271 were highly conserved, and PB2 mutant strains were not the dominant strains. The PB2 mutant had high antigenicity with the vaccine. The PB2 mutant strain is sensitive to NA inhibitors. The three-dimensional model predicted that PB2-D701N mutation could enhance virulence and affect transmissibility of influenza virus, while PB2-A271S mutation could affect polymerase activity and polymerase complex synthesis of influenza virus.

Objective To propose a regression tree model for the estimation of blood pressure using the minimalist characteristics of photoplethysmography(PPG)signals.Methods Fifteen characteristic parameters were extracted from the PPG signals,and the 4 parameters with the highest correlations with blood pressure were screened using the Spearman correlation coefficient to construct a regression tree model for blood pressure estimation using the minimalist characteristics.Results The estimation errors of systolic and diastolic blood pressures in the constructed model were(-0.02±3.63)mmHg and(-0.04±2.10)mmHg,respectively.Conclusion The proposed regression tree model has a simple structure and high accuracy,which is of great significance for using a single-channel PPG signal for blood pressure estimation in wearable devices.

OBJECTIVE: To establish a rapid detection and genotyping method for SARS-CoV-2 Omicron BA.4/5 variants using CRISPPR-Cas12a gene editing technology. METHODS: We combined reverse transcription-polymerase chain reaction (RT-PCR) and CRISPR gene editing technology and designed a specific CRISPPR RNA (crRNA) with suboptimal protospacer adjacent motifs (PAM) for rapid detection and genotyping of SARS- CoV-2 Omicron BA.4/5 variants. The performance of this RT- PCR/ CRISPPR-Cas12a assay was evaluated using 43 clinical samples of patients infected by wild-type SARS-CoV-2 and the Alpha, Beta, Delta, Omicron BA. 1 and BA. 4/5 variants and 20 SARS- CoV- 2-negative clinical samples infected with 11 respiratory pathogens. With Sanger sequencing method as the gold standard, the specificity, sensitivity, concordance (Kappa) and area under the ROC curve (AUC) of RT-PCR/CRISPPR-Cas12a assay were calculated. RESULTS: This assay was capable of rapid and specific detection of SARS- CoV-2 Omicron BA.4/5 variant within 30 min with the lowest detection limit of 10 copies/μL, and no cross-reaction was observed in SARS-CoV-2-negative clinical samples infected with 11 common respiratory pathogens. The two Omicron BA.4/5 specific crRNAs (crRNA-1 and crRNA-2) allowed the assay to accurately distinguish Omicron BA.4/5 from BA.1 sublineage and other major SARS-CoV-2 variants of concern. For detection of SARS-CoV-2 Omicron BA.4/5 variants, the sensitivity of the established assay using crRNA-1 and crRNA-2 was 97.83% and 100% with specificity of 100% and AUC of 0.998 and 1.000, respectively, and their concordance rate with Sanger sequencing method was 92.83% and 96.41%, respectively. CONCLUSION By combining RT-PCR and CRISPPR-Cas12a gene editing technology, we successfully developed a new method for rapid detection and identification of SARS-CoV-2 Omicron BA.4/5 variants with a high sensitivity, specificity and reproducibility, which allows rapid detection and genotyping of SARS- CoV-2 variants and monitoring of the emerging variants and their dissemination.
Humans ; COVID-19 ; CRISPR-Cas Systems ; Genotype ; Reproducibility of Results ; Reverse Transcriptase Polymerase Chain Reaction ; SARS-CoV-2/genetics* ; RNA ; COVID-19 Testing

Objective:To explore the value of machine learning models based on multiple structural MRI features for diagnosis of Parkinson disease (PD).Methods:The clinical and imaging data of 60 PD patients (PD group) diagnosed in the Neurology Department of the Second Affiliated Hospital of Soochow University from November 2017 to August 2019 and 56 normal elderly people (NC group) recruited from the community were retrospectively analyzed. All subjects underwent brain MR imaging. Multiple structural MRI features were extracted from cerebellum, deep nuclei and of brain cortex based on different partition templates. The Mann-Whitney U test, as well as least absolute shrinkage and selection operator regression were used to select the most discriminating features. Finally, logistic regression (LR) and linear discriminant analysis (LDA) classifier combined with the 5-fold cross-validation scheme were used to construct the models based on structural features of cerebellum, deep nuclei and cortex, and a combined model based on all features. The receiver operating characteristic curves were drawn, and the diagnostic performance and clinical net benefit of each model were evaluated by the area under curve (AUC) and the decision curve analysis (DCA). Results:In total, four cerebellum (asymmetry index of Lobule Ⅵ volume, asymmetry index of Lobule ⅦB cortical thickness, asymmetry index of total gray matter volume and absolute value of right Lobule Ⅵ gray matter volume), 3 deep nuclei (absolute value of right nucleus accumbens volume, absolute and relative value of total nucleus accumbens volume) and 3 cortex features (local gyration index of left PFm, local fractal dimension of right superior frontal gyrus and sulcal depth of left superior occipital gyrus) were selected as the most discriminating features, and the related models were constructed. In validation set, the AUC of cerebellum, deep nuclei, cortex and combined models for diagnosis of PD based on LR classifier were 0.692, 0.641, 0.747 and 0.816; the AUC of cerebellum, deep nuclei, cortex and combined models for diagnosis of PD based on LDA classifier were 0.726, 0.610, 0.752 and 0.818. The diagnostic efficiency of the combined models based on LR and LDA classifiers were significantly better than those of other models ( P<0.05). The DCA curve demonstrated that the combined models based on LR and LDA classifiers showed the highest clinical net benefit. Conclusion:The combined models with all structural features of cerebellum, deep nuclei and cortex included based on LR and LDA classifiers showed favorable performance and clinical net benefit for diagnosis of PD, which have the potential application value in clinical diagnosis.

Objective:To analyze and reveal the genetic evolution and variation of influenza viruses in cases of co-infection in Guangdong Province.Methods:Throat swab samples were collected from four cases of H1N1pdm and H3N2 co-infection for viral isolation. The isolated strains were subjected to antigen analysis and neuraminidase inhibitor susceptibility test. High-throughput sequencing was used to detect the sequences of strains in three throat swab samples and one virus strain, and then genetic variations were analyzed.Results:Four influenza viruses were isolated with one strain of H1N1pdm and three of H3N2 subtype, and all of them were genetically similar to the vaccine strain in 2022-2023. The HA genes of H1N1pdm and H3N2 strains belonged to clade 6B.1A.5a.2a and 2a.3a.1, respectively. The isolated strains belonged to the same clade as the strains prevalent in Guangdong during the same period. No drug-resistant variations were detected in N1 or N2 gene, and the isolated strains were sensitive to oseltamivir and zanamivir.Conclusions:H1pdm subtype had stronger replication ability than H3 subtype in the influenza viruses isolated from co-infected cases. H1N1pdm and H3N2 subtype influenza viruses were genetically similar to the strains circulating in Guangdong at the same time. The isolated H1N1pdm and H3N2 strains were sensitive to both oseltamivir and zanamivir, indicating that they could continue to be used in the treatment of influenza virus infections caused by one or two genotypes.

Objective:To understand the etiology of a confirmed case of Coronavirus Disease 2019 (COVID-19).Methods:The pharyngeal swabs, serum and nasal swabs of a case of COVID-19 were inoculated into Vero-E6 cell tubes for virus isolation. The cytopathic effect (CPE) were observed daily. Collecting cell’s isolation when CPE was over 75%, after repeated freezing and thawing for 3 times, the supernatant was centrifugally taken, and the images of the virus were obtained by transmission electron microscopic observation, and the nucleic acid of the virus was extracted, second generation sequencing and sequence evolution analysis were used to identify and type the virus strains.Results:One strain of 2019 novel coronavirus (2019-nCoV) was successfully isolated from the nasal swab of this case of COVID-19, and one strain of herpes simplex virus type 1 (HSV-1) was also successfully isolated from the throat swab of the same case.Conclusions:COVID-19 cases have the possibility of co-infection with 2019-nCoV and HSV-1.

Objective:To obtain the genome sequences of SARS-CoV-2 in respiratory specimens in Guangdong Province with next-generation sequencing (NGS) and analyze the factors influencing sequencing.Methods:Eight upper and lower respiratory tract specimens were collected from patients with SARS-CoV-2 infection in Guangdong Province in January 2020. RNA library construction was used to obtain the genome sequences of SARS-CoV-2. A bio-informatics software package (CLC Genomics Workbench 12.0) was used to analyze and compare the genomic sequences.Results:Five SARS-CoV-2 genome sequences were obtained from the eight specimens and two were obtained from lower respiratory tract specimens. The nucleotide homology to SARS-CoV-2 was 97.74%-99.90%. The Ct values were lower, while the sequencing depth, coverage, relative abundance and genome integrity were higher in sequencing the SARS-CoV-2 in lower respiratory tract specimens.Conclusions:The low Ct value of SARS-CoV-2 in the samples was good for sequencing.

Objective:To understand the genetic variation and epidemiological characteristics of human respiratory syncytial virus (HRSV) in Guangzhou.Methods:Nasopharyngeal swabs specimens were collected from 0-6 year old children hospitalized with acute respiratory infection, then HRSV was tested and genotyped by RT-PCR. Phylogenetic tree was bulit using MEGA 6.0 software. NetNGlyc 1.0 server was used to predict the potential N-linked glycosylation sites.Results:A total of 1 225 nasopharyngeal specimens were collected, including 783 males and 442 females. The median ( P25, P75) age was 8 (3, 24) months. Among the 209 HRSV-positive cases (17.06%), 117 cases (55.98%) were HRSV-A and 92 cases (44.02%) were HRSV-B. The two distinct subgroups (HRSV-A and HRSV-B) alternately played dominant role to cause HRSV infection and exchange almost once every two years. The HRSV prevalence rate decreased with age. The HRSV-positive rate among children under 2 years old was 18.83% (196 cases), accounting for 93.78% of the total positive cases. There were 32 HRSV positive cases co-infected with at least one respiratory virus, with the co-infection rate of 15.31%. Phylogenetic tree analysis of the second hypervariable region (HVR2) of the G protein classified the HRSV-A specimens into ON1 ( n=62) and NA1 ( n=2) genotypes while all HRSV-B specimens belonged to BA genotype ( n=53). The HVR2 of the G protein varied in using stop condon, amino acid substitutions, glycosylation sites. Conclusion:Children under 2 years old were the high risk population of HRSV infection in Guangzhou. ON1 genotype turned into a primary genetype of the HRSV-A subgroup while BA genotype dominated the HRSV-B subgroup. A greater diversification of amino acid substitutions, and some deletion and insertion of glycosylation sites embodied the polymorphism of G protein as main protective antigen.

Objective:To ananlyze the toxic effects and mechanisms of Cr (Ⅵ) subchronic exposure based on metabonomics techniques.Methods:Twenty-nine female Sprague-Dawley rats were randomly divided into control group, low dose group and high dose group, 10, 9, 10, respectively. The control group, low dose group and high dose group were treated with 0, 10, 50 mg/L Cr (Ⅵ) for 90 days respec tively. The serum samples of rats with different dose of Cr (Ⅵ) treatment were detected Using UPLC-Q-TOF-MS/MS technique and data was analyzed by PCA, PLS-DA and OPLS-DA to compare with metabolic profile in different Cr (Ⅵ) dose treatments. Pathway analysis was performed using MetaboAnalyst 4.0 software.Results:UPLC-Q- TOF-MS/MS has stable detection performance and reliable experimental data. The control group, low Cr (Ⅵ) and high Cr (Ⅵ ) metabolic profiles of rats serum differences was obviously, and there is significant difference of serum metabolic profile among rats treated with different dose of Cr (Ⅵ) . 18 differential metabolites were screened between Cr (Ⅵ) low dose group and control group, 23 differential metabolites between Cr (Ⅵ) high dose group and control group. Compared to control group, there were 13 differential metabolites in both Cr (Ⅵ) high dose group and Cr (Ⅵ ) low dose group, such as 3-Hydroxy-11Z-octadecenoylcarnitine, Anserine, Farnesyl pyrophosphate, Linoleoyl ethanolamid e, Linoleyl carnitine, Lithocholate 3-O-glucuronide, LysoPC [20∶2(11Z, 14Z) ], LysoPC[20∶3 (5Z, 8Z, 11Z) ], LysoPC[22∶2(13Z, 16Z) ], PG[16∶0/22∶5(7Z, 10Z, 13Z, 16Z, 19Z) ], PI[18∶1 (11Z) /20∶4(5Z, 8Z, 11Z, 14Z) ], PI[20∶3(5Z, 8Z, 11Z) /18∶0], Serotonin. These differential metabolites were related to Glycerophospholipid metabolism, Tryptophan metabolism, Pentose and glucuronate interconversions, Terpenoid backbone biosynthesis.Conclusion:Cr (Ⅵ) subchronic exposure could induce the significant difference of serum metabolic profile. The differential metabolites induced by Cr (Ⅵ) subchronic ex- posure were mainly related to amino acid and lipid metabolism.

Objective:To understand the genetic variation and epidemiological characteristics of human respiratory syncytial virus (HRSV) in Guangzhou.Methods:Nasopharyngeal swabs specimens were collected from 0-6 year old children hospitalized with acute respiratory infection, then HRSV was tested and genotyped by RT-PCR. Phylogenetic tree was bulit using MEGA 6.0 software. NetNGlyc 1.0 server was used to predict the potential N-linked glycosylation sites.Results:A total of 1 225 nasopharyngeal specimens were collected, including 783 males and 442 females. The median ( P25, P75) age was 8 (3, 24) months. Among the 209 HRSV-positive cases (17.06%), 117 cases (55.98%) were HRSV-A and 92 cases (44.02%) were HRSV-B. The two distinct subgroups (HRSV-A and HRSV-B) alternately played dominant role to cause HRSV infection and exchange almost once every two years. The HRSV prevalence rate decreased with age. The HRSV-positive rate among children under 2 years old was 18.83% (196 cases), accounting for 93.78% of the total positive cases. There were 32 HRSV positive cases co-infected with at least one respiratory virus, with the co-infection rate of 15.31%. Phylogenetic tree analysis of the second hypervariable region (HVR2) of the G protein classified the HRSV-A specimens into ON1 ( n=62) and NA1 ( n=2) genotypes while all HRSV-B specimens belonged to BA genotype ( n=53). The HVR2 of the G protein varied in using stop condon, amino acid substitutions, glycosylation sites. Conclusion:Children under 2 years old were the high risk population of HRSV infection in Guangzhou. ON1 genotype turned into a primary genetype of the HRSV-A subgroup while BA genotype dominated the HRSV-B subgroup. A greater diversification of amino acid substitutions, and some deletion and insertion of glycosylation sites embodied the polymorphism of G protein as main protective antigen.