Epidemiological characteristics and genotype of norovirus outbreaks in schools in Xicheng District of Beijing from 2017 to 2022 / 中国学校卫生

Objective@#To analyze the epidemiological and molecular characteristics of norovirus outbreaks in schools in Xicheng District of Beijing from 2017 to 2022, so as to provide evidence for the prevention and control of norovirus outbreaks in schools.@*Methods@#Data of norovirus outbreaks in schools in Xicheng District, Beijing during 2017 to 2022 were collected and analyzed by descriptive epidemiological methods. Realtime PCR was used to detect the nucleic acid of group GⅠand GⅡnorovirus, the positive norovirus nucleic acid samples were sent to Beijing Center for Disease Control and Prevention for molecular typing.@*Results@#From 2017 to 2022, 185 norovirus outbreaks were reported in schools in Xicheng District, including 166 cluster outbreaks and 19 outbreaks. A total of 2 044 cases were reported, with a total attack rate of 13.92%. There were two peaks in the outbreak time, which were from March to June after the spring semester and from October to December after autumn semester. Primary schools were the most common place of occurrence (101 cases), followed by nursery institutions (68 cases) and secondary schools (16 cases). There were statistically significant differences in the incidence rates among different sites(12.37%, 22.78%, 8.47%, χ2=263.34, P<0.01). There were significant differences in the incidence of vomiting, diarrhea, nausea and stomachache among different students (χ2=263.33, 90.58, 20.42, 30.29, P<0.01). Vomiting was the main symptom in primary school and nursery school children (96.41%, 98.28%), and the diarrhea rate was higher in middle school students (68.22%). The outbreaks were mainly caused by type GⅡ norovirus. The genotype from 2017 to 2021 showed the characteristics of diversity, mainly GⅡ.2[P16], but there was no significant advantage for the GⅡ.2 [P16] during 2019 to 2021.@*Conclusions@#The norovirus outbreak in schools in Xicheng district of Beijing from 2017 to 2022 are mainly caused by GⅡ type genome. The main genotype is GⅡ.2[P16]. Norovirus infection mainly occurred in primary schools and kindergartens. For the vulnerable populations, it is necessary to improve the capacity to early identification, student infectious disease management, active infection control and prevention measures, and pathogen surveillance and sporadic case monitoring.

Biomimetic oxidase sensor based on functionalized surface of carbon nanotubes and iron prophyrins for catechol detection.

A novel and highly stable biomimetic oxidase sensor system was designed for catehol detection. FePP used as biomimetic horseradish peroxidase (HRP) was immobilized onto modified multi-walled carbon nanotubes (MWCNTs). Functional groups such as -OH, -NH2 and -COOH were introduced onto the surface of MWCNTs to provide biomimetic microenvironment for iron porphyrins (FePP). Stable biomimetic enzyme electrode has been developed to detect catechol as a simple, economical and efficient method. At optimal condition, the detection limit of OH-MWCNTs/FePP/Nafion was 3.754 × 10- 6 M. After stored at - 4 °C for 35 days, the oxidation current value still maintained 98.3% of initial activity. In repetitive nature test, relative standard deviation (RSD) of oxidation current remained within 1.0% after ten consecutive measurements in the same concentration of catechol solution, while most of reported oxidase sensor was within 2.0% under the same condition.

Acetylcholinesterase biosensor based on functionalized surface of carbon nanotubes for monocrotophos detection.

Monocrotophos (Ops) has been widely used as pesticide in crop production but simultaneously could accumulate in the nature and seriously impact food safety and human health. It is necessary to develop a high sensitivity biosensor for accurate and fast detection of OPs. In this study, multi-walled carbon nanotubes (MWCNTs) were selected as acetylcholinesterase (AChE) carrier and their surface was modified by introducing different functional groups (-SH, -NH2, -Cl, -OH), hydrophobic alkyl groups (-CH3, -(CH2)2CH3, -(CH2)7CH3, -(CH2)15CH3) and ionic liquids (-IL1, -IL2). The interaction mechanism of MWCNTs functionalized surface and AChE has been revealed by studying characteristics of AChE immobilized on different carrier surface. Finally, compared with reported references and above other modifiers, we found that MWCNTs surface modified by -IL1 was the best carrier for AChE and the detection limit of IL1-MWCNTs/AChE/GCE was 3.3 × 10-11 M. At optimum reaction condition (pH 7.0, AChE loading 0.25 U, Inhibition time 14 min), storability test indicated reactivity of IL1-MWCNTs/AChE/GCE remained above 98.5% within two weeks. For real vegetable sample detection, the recoveries of IL1-MWCNTs/AChE/GCE were found to be between 90.0% and 104%. These results demonstrated novel biosensors could act as device of high sensitivity for accurate and fast detection of OPs.

Observation on growth status of Blastocystis hominis in three media / 中国血吸虫病防治杂志

Objective To observe the growth situation of Blastocystis hominis in vitro and select the optimal method for culti?vation of B. hominis in different media. Methods Ten positive stools with B. hominis were inoculated in three different media for cultivating,namely 1640,Jone’s medium and vitro medium. And the stools with good growth status and high quantities of B. hominis were chosen to inoculate in the three media with equal amount after subcultivation,and the number of B. hominis was counted every 24 h for ten days,and the morphological changes and growth status were also observed. Results The densities of B. hominis in the 1640 and Jone’s medium were higher than that in the vitro medium 48 h after the inoculation. The same stool sample was inoculated to the three different media and observed for ten days,and the results indicated that the growth of B. homi?nis presented regular changes in the three media,the growth peaks were on the third,sixth and ninth day post inoculation;and the density of B. hominis was the highest in the Jone’s medium. The morphology of B. hominis was the clearest and most dynamic in the vitro medium,while various reproductive forms were observed in the Jone’s medium. Conclusion Jone’s medium is suitable for the growth of B. hominis and can be the first choice for the cultivation of B. hominis in vitro,and vitro medium is the best medium for observing the growth situation of B. hominis.

Immune identification and mass spectrometric analysis of the soluble antigens from Babesia microti / 中华地方病学杂志

Objective To analyze the fractional proteins and immunoreactivity of the soluble antigens from Babesia microti (B.microti),and find the candidate antigens for diagnosis with high sensitivity and specificity.Methods BALB/c mice were inoculated with B.microti-infected red blood cells by intraperitoneal injection.The B.microti were collected from the infected red blood cells when the infection rate reached its peak (infection rate ＞70％),then the soluble antigens were extracted by repeated freezing-thawing and ultrasonic method.The mice sera before and after the infection with B.microti for 7,14,21,28,35,42,49 and 56 days were also collected.The polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze protein components of the soluble antigens of B.microti and the Western blot was used to analyze the immunoreactivity of the soluble antigens with the pooled mice sera before and after the infection.The specific positive protein bands were identified by Liquid chromatography electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS),and the amino acid sequences of the proteins were analyzed by bioinformatics tools.Results The results from SDS-PAGE analysis indicated that the soluble antigens of B.microti showed distinct protein bands with the range between 12 and 185 × 103 (kDa,relative molecular mass,Mr),among which 9 main bands and 12 minor bands were obtained.In the Western blot analysis,the protein bands with Mr at 40 and 45 kDa could be recognized by pooled mice sera 7 days after infection;the protein bands with Mr at 40,45,54 and 95 kDa could be recognized by pooled mice sera 14 days after infection;the protein bands with Mr at 27,40,45,54,95 and 110 kDa could be recognized by pooled mice sera 21 days after infection.While,the protein bands with Mr at 27,40,45,54,95,1 10 kDa and other weak-reactive bands were recognized by pooled mice sera 28-56 days after infection,and the reaction became stronger with the infection continued.There were 336 proteins,including surface antigen,heat shock protein 70,seroreactive antigen,Eta subunit of chaperonin containing t-complex polypeptide 1 and unnamed protein products,were identified as the components of soluble antigens after mass spectrometry and sequence analysis.Conclusion The 40,45 and 54 kDa protein components from the soluble antigens of B.microti may be ideal candidate antigens for diagnosis,andtheir potential applications in diagnosing of human babesiosis deserve further study.

Establishment of A1E3 and B1C4 monoclonal antibody-based ELISA for de-tecting circulating antigen of Schistosoma japonicum and its preliminary ap-plication / 中国血吸虫病防治杂志

Objective To establish A1E3 and B1C4 monoclonal antibody-based ELISA for detecting circulating antigen of Schistosoma japonicum and explore its application value in the field. Methods The characteristics of A1E3 and B1C4 monoclonal antibodies were analyzed by SDS-PAGE and Western blotting. The SEA-based ELISA was used to evaluate the titers of A1E3 and B1C4. The orthogonal test was used to determine the best concentration of coating antibody B1C4 and optimal working concentra-tion of A1E3-HRP. Under the optimal conditions,the serum samples of 20 acute schistosomiasis cases,46 chronic schistosomiasis cases,and 20 control sera were tested to evaluate its detection sensitivity and specificity. Seventy-two antibody positive serum sam-ples from Jiangling County of Hubei Province were detected and compared to a commercially available ELISA kit,to evaluate the detection effects of this method. Results The results of SDS-PAGE demonstrated that the purified A1E3 and B1C4 contained a clear heavy chain with molecular weight of 88 000 and 52 000 respectively and had the same light chain with molecular weight of 20 000;while Western blotting demonstrated that A1E3 and B1C4 could be recognized by SEA and serum samples of acute schis-tosomiasis cases. The SEA-based ELISA demonstrated the titers of B1C4 and A1E3 were 1∶105 and 1∶30 000,respectively. The serum samples from all the acute cases and 86.9% of the chronic cases showed a positive reaction. All of the control sera from healthy persons gave a negative response. The positive rates of the double monoclonal antibody ELISA and commercial ELISA for detecting the circulating antigen were 45.8%and 43.1%respectively,and there was no significant difference between the results of the two methods. Conclusion A1E3 and B1C4 monoclonal antibody-based ELISA is established successfully. It exhibits a high sensitivity and specificity in detecting circulating antigen of Schistosoma japonicum.