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Echovirus 11 (E11) has gained attention owing to its association with severe neonatal infections. From 2018 to 2023, a surge in severe neonatal cases and fatalities linked to a novel variant of genotype D5 was documented in China, France, and Italy. However, the prevention and control of E11 variants have been hampered by limited background data on the virus circulation and genetic variance. Therefore, the present study investigated the circulating dynamics of E11 and the genetic variation and molecular evolution of genotype D5 through the collection of strains from the national acute flaccid paralysis (AFP) and hand, foot, and mouth disease (HFMD) surveillance system in China during 2000–2022 and genetic sequences published in the GenBank database. The results of this study revealed a prevalent dynamic of E11 circulation, with D5 being the predominant genotype worldwide. Further phylogenetic analysis of genotype D5 indicated that it could be subdivided into three important geographic clusters (D5-CHN1: 2014–2019, D5-CHN2: 2016–2022, and D5-EUR: 2022–2023). Additionally, variant-specific (144) amino acid mutation sites and positive-selection pressure sites (132, 262) were identified in the VP1 region. Cluster-specific recombination patterns were also identified, with CVB5, E6, and CVB4 as the major recombinant viruses. These findings provide a preliminary landscape of E11 circulation worldwide and basic scientific data for further study of the pathogenicity of E11 variants.

Background. Noroviruses are the most frequent cause of epidemic acute viral gastroenteritis in China. Objectives. The aim of this study was to determine the molecular epidemiological characteristics of norovirus outbreaks and the molecular genetic features of norovirus in Zhejiang Province during 2021. Methods. First, the local Centers for Disease Control and Prevention in the outbreak area conducted on‐site epidemiologic investigations and collected samples from ill patients for initial testing. The general epidemiologic characteristics of the demographic information are presented through descriptive analysis. Positive samples were sent to the Microbiology Laboratory of Zhejiang Provincial Center for Disease Control and Prevention for further verification. The presence of norovirus genogroups I (GI) and II (GII), along with sapovirus, was detected. Subsequently, the specimens positive for norovirus were sequenced for genotyping purposes. Furthermore, the whole genomes of positive samples were sequenced, enabling the characterization of both nucleotide and amino acid differences within the virus. Finally, phylogenetic trees were constructed to further analyze and understand the genetic relationships among the detected viruses. Result. 227 norovirus outbreaks were reported in Zhejiang Province, China, during 2021. Schools were the main setting while January was the peak month for outbreaks. A total of 17 diverse genotypes of norovirus were identified in 2021, and GII.P16‐GII.2 was the most frequent genotype (30.19%). Seven genomes (five GI.P4‐GI.5 and two GII.P16‐GII.2) were obtained. Although GI.P4‐GI.5 is considered to be a rare genotype of norovirus, the prevalence might have been underestimated. Capsid microvariation of GII.2 displayed histo‐blood group antigen binding patterns compared to the GII.2 prototype, although VP1 sequences were considered to have a minimal impact on antigenicity. Conclusion. This study revealed the diversity of norovirus strains' genotypes circulating in Zhejiang Province in 2021. Continued molecular surveillance of noroviruses should be strengthened in our further efforts to the development of vaccines. [ABSTRACT FROM AUTHOR]

The dead-time effects of single-phase rectifier causes voltage and current distortions, zero-current clamping effects,etc. To solve the problems, the dead-time and zero-current clamping effects were analyzed, and a novel dead time compensation method of single-phase PWM rectifier was proposed by the observation of grid input voltage based on resonant controller phase-looked loop. The new method avoids the noise of the current detection, so that zero-crossing detection is more accurate, and does not cause the phase delay. Comparative analysis was conducted with traditional dead time compensation method based on the current. The proposed scheme can effectively improve the degree of sinusoidal current waveform, and eliminate the need to detect the direction of the current conventional solutions drawbacks. This algorithm is simple and has a practical value. The simulation and experiment results show that the grid input current total harmonic distortion with grid input voltage observation is lower and compensation effect is better. [ABSTRACT FROM AUTHOR]

In order to research the effects of the module voltage fluctuation on the output voltage of modular multilevel converter (MMC) the mathematical model of modular multilevel converter (MMC) was established and the analytical expression of the converter's output voltage was deduced on the condition that high frequency harmonics caused by modulation algorithm was neglected. And for the circulating current restraint control method which was often used, the expression of output voltage was simplified. The analysis shows that caused by the fluctuation of module capacitor voltage, there are odd harmonics in the output voltage. Moreover there is a deviation between the actual value and the reference value of the output voltage. In order to measure the value of the deviation, fluctuation coefficient of module capacitor voltage is defined, and it may draw a conclusion that the deviation is depended on the ratio of the fluctuation coefficient to the modulation degree of output voltage. To make sure that the converter can work properly the ratio should be limited in a certain range. At last, experiment results demonstrate the validity of the theoretical derivation and analysis. [ABSTRACT FROM AUTHOR]

Objective: To study the molecular characteristic of norovirus in 3 outbreaks of gastroenteritis in Zhejiang province., Methods: During January 2008 and December 2009, fecal specimens of patients were collected from 3 outbreaks of acute viral gastroenteritis. Noroviruses were detected by Real-time RT-PCR. Part of the positive samples were randomly selected and detected by RT-PCR. PCR products were sequenced. Sequence analysis was undertaken based on partial sequence of RNA dependent RNA polymerase (RdRp) and capsid protein gene. Some positive samples were amplified by 3'RACE (rapid amplification of cDNA 3'ends), 3200 bp in length. The exact whole ORF2, ORF3 and 3'untranslation regions (UTR) gene of norovirus were identified., Results: There were in total 3 outbreaks of viral gastroenteritis caused by norovirus being reported. A total of 62 stools were obtained from cases with acute gastroenteritis. Noroviruses were detected in 41 cases including 27 strains of genogroup I norovirus and 9 strains of genogroup II norovirus, 5 strains of genogroup I + II norovirus. Four genotypes including GI.8, GII.b, GI.2/GI.6 recombination together with co-infection of GI.8 and GII.b were detected., Conclusion: Norovirus was confirmed as the major cause of outbreaks of viral gastroenteritis in Zhejiang province and multiple genotype of norovirus were identified from the outbreaks. It was the first time to have found a recombinant of GI.6 capsid and GI.2 polymerase norovirus as well as the co-infection of GI.8 and GII.b norovirus in the same sample.

Objective: Study meningoencephalitis virus isolated from the Coxsackie B5 virus(CVB5 virus) VP1 gene characteristics of Zhejiang Province in 2008 and compare with other countries CVB5 prototype isolates, and to explore the relationship of variation of the Virus VP1 areas and epidemic viral meningoencephalitis, Methods: Hep-2 and RD cells in cerebrospinal fluid and stool specimens for virus isolation, positive isolates combination with intestinal type of serum. On the separation of virus extracted RNA, and then RT-PCR amplified VP, gene CVB5 virus fragments, and purification of sequencing products, using DNAMAN and Bioedit analytical processing software., Results: The VP1 gene of CVB5 isolated from Zhejiang province meningoencephalitis viral in 2008 was 735bp. There were no missing and insertion of nucleotide . Strains isolated from ZJ/12/02 with the nucleotide and amino acid sequence of the highest phylogenetic tree showed that they were not the same branch., Conclusion: The mutation caused by viral meningoencephalitis virus CVB5 Zhejiang province in 2008 was smaller. Viral meningoencephalitis distributed in some areas in the province had no significant prevalence.

Objective: To study the molecular epidemiological characteristics of Norovirus gastroenteritis outbreaks in Zhejiang., Methods: During January 2006 and December 2007, fecal specimens of patients collected from outbreaks of acute viral gastroenteritis were tested for Norovirus. Epidemiological data were also collected. Noroviruses were detected by a reverse transcription polymerase chain reaction (RT-PCR) and Real-time RT-PCR. Some positive samples were randomly selected and RT-PCR products were sequenced. Comparing to the nucleotide sequences of norovirus genotype I, II reference strains from GenBank, sequence analysis was undertaken based on partial sequence of RNA dependent RNA polymerase (RdRp) and capsid protein (VP1) gene., Results: 5 outbreaks of viral gastroenteritis caused by Norovirus were reported. A total of 63 stools were obtained from cases with acute gastroenteritis. Noroviruses alone were detected in 45 cases and the illness appeared in autumn. Phylogenetic analysis revealed that Norovirus belonged to G II/G II 4 type. The strains isolated from Zhejiang were almost identical on G II/4 variants that causing epidemics in Beijing and in The Netherlands with the homology of 99.7% and 98.5%-99.0% respectively. Phylogenetic analysis revealed that the isolates were located at the same branch as the norovirus G II/4 variants found in Beijing and Netherlands., Conclusion: Norovirus is a major cause of outbreaks of viral gastroenteritis in Zhejiang province Genogroup II/4 variants viruses were the prevalent strains.

Objective: To study the gene characterization of enterovirus 71 (EV71) virus strains isolated from clinical specimens of children with hand-foot-and-mouth disease (HFMD) in Zhejiang province., Methods: Virus were isolated from clinical samples including stool, throat swab and vesicle from patients with HFMD. The EV71 isolates were identified by microneutralization assay and reverse transcriptase PCR (RT-PCR) with specific primer pair for VP1 genes of EV71. Complete VP1 gene sequences (891 nucleotides) for recent 6 EV71 isolates were determined and compared with that of A, B, C genotype reference EV71 strains and 11 EV71 China isolates available from GeneBank by homogeneity and phylogenetic tree analyses., Results: 9 strains of EV were isolated from 14 clinical specimens. Data from microneutralization and RT-PCR results indicated that all the strains belong to EV71. The nucleotide and amino acid homogeneity of these 6 Zhejiang strains with the representative isolates of A and B genotypes were 82.9%-85.5% and 94.9%-98.0% respectively; with the representative isolates of C were 89.2%-94.1% and 97.0%-99.0% respectively. There were 91.0%-92.2%, 90.2%-90.3%, 89.2%-89.5%, 96.7%-96.9% nucleotide, homology with representative strains of C1, C2, C3,C4 subgenotypes of EV71. The nucleotide homogeneity of these 6 EV71 isolated strains with 9 previously isolated Chinese strains appeared to be 93.8%-97.1%. These 6 EV71 isolated strains were within genotype C subgenogroup C4 in the phylogenetic tree., Conclusion: The recently identified EV71 isolates in Zhejiang province belonged to subgenogroup C4.

Objective: To establish a new technique for SARS-CoV antibody test to detect infection of severer acute respiratory syndrome (SARS)., Methods: Nucleocapsid gene was obtained by reverse transcription and polymerase chain reaction from a SARS patient and inserted into the vector pFastBacHTa expressing baculovirus. Insect Sf9 cells were transfected with the recombinant baculovirus expressing SARS nucleocapsid antigen and then cultured, fixed by acetone so as to make SARS-specific antigen. Immunofluorescence assay (IFA) technique and plaque reduction neutralization test (PRNT) were used to detect 7 samples of sera of 4 newly diagnosed SARS patients collected in different days, 48 samples of convalescent sera of SARS patients, 24 serum samples of healthy person undergoing physical examination, and 40 serum samples from non-SARS patients with fever by double blind test., Results: The recombinant SARS-specific antigen reacted only with SARS positive sera but not with normal sera. Double blind test showed that 45 of the 46 PRNT positive sera were IFA positive with an accordance rate of 97.8%. 7 samples of sera from 4 SARS patients in acute progressive stage in Guangdong province were all IFA positive. SARS antibody could be detected since the sixth day after onset, and the titer increased from 1:40 to 1:600 on the ninth day., Conclusion: Immunofluorescence assay is highly specific and sensitive in detection of SARS. This reagent is safe and easy to prepare.