Epidemic characteristics and genotyping of varicella in Yangzhou in 2021 / 公共卫生与预防医学

Objective To analyze the epidemic characteristics of varicella and the genetic characteristics of varicella zoster virus (VZV) in Yangzhou in 2021, and to provide a theoretical basis for the scientific prevention and control of varicella in Yangzhou. Methods Descriptive epidemiological analysis was carried out on the varicella outbreaks reported in Yangzhou in 2021. Throat swabs or herpes fluid samples from varicella cases in 2021 were collected, and the viral nucleic acid was detected by real-time fluorescent quantitative PCR. The genotype and evolutionary relationship of the virus strain were determined according to the 6 SNPs in the ORF22 gene fragment sequence. Results In 2021, there were 20 varicella outbreaks in Yangzhou, involving 147 cases, all of which occurred in kindergartens and primary and secondary schools, and the peak incidence was in the age group of 4-7 years old. The high incidence time of the outbreaks was from May to July, and from November to January of the next year. The varicella vaccination rate of the cases was low, and all were 1-dose vaccination. The gene sequencing results of 8 samples were J/clade 2, and 3 of them had A-C synonymous mutation at position 37997 in ORF22 sequence. Conclusion In 2021, varicella outbreaks in Yangzhou occurred mainly in kindergartens and schools. Preschool children are susceptible, all of which are caused by J/clade 2 varicella-zoster virus. It is suggested to strengthen the monitoring and management of the varicella epidemic situation in schools in the city, and at the same time incorporate the varicella vaccine into the routine immunization program of the city and strengthen 2 doses of varicella vaccination.

Development and evaluation of real-time fluorescence recombinase aided amplification assay without extracting nucleic acid for detection of adenovirus type 3 / 中华实验和临床病毒学杂志

Objective@#To establish a real-time fluorescence recombinase acid amplification (RAA) method for the detection of adenovirus type 3(HAdV-3)without extraction nucleic acid.@*Methods@#According to the conserved sequence of adenovirus type 3 gene, a pair of primers and a probe were designed, and a real-time fluorescence RAA without extracting nucleic acid was established and optimizing the condition of DNA-free extraction. The sensitivity of the method was analyzed by a series of dilution and the specificity of the method was evaluated by detecting the original samples of other respiratory viruses. The clinical samples of HAdV-3 were detected and compared with the traditional real-time fluorescence quantitative PCR method for nucleic acid extraction.@*Results@#The sensitivity of the real-time fluorescence RAA method was as high as that of qPCR in the detection of 10 series diluted HAdV-3 strains. The highest corresponding CT value of qPCR was 36.87. The sensitivity of the real-time fluorescence RAA method was similar to that of the real-time fluorescence quantitative PCR method . There was no cross-reaction to other common types of respiratory viruses. The two method were used to detect 56 clinical samples at the same time, and the result were completely consistent.@*Conclusions@#We provide the first report of the real-time fluorescent RAA assays for the detection of HAdV-3 without extracting nucleic acid and it has high sensitivity and specificity. Is suitable for rapid detection of HAdV-3 in clinical laboratories and on-site unite.

Pathogen spectrum of viral encephalitis in children living in Hebei province, China from May to December 2017 / 中华实验和临床病毒学杂志

Objective@#To investigate the pathogenic characteristics of viral encephalitis in children living in Hebei province.@*Methods@#We randomly collected cerebrospinal fluid specimens from a total of 399 children diagnosed with viral encephalitis in Hebei Children′s Hospital from May to December 2017. Real-time fluorescence quantitative PCR and Sanger sequencing were used to detect viral nucleic acids in cerebrospinal fluid by an automatic laboratory station. Statistical analysis was performed on the experimental data using SPSS 21.0 software and the clinical data were analyzed. Comparison of infection rates of EV encephalitis in different months, using line × column chi-square test. The MRI and EEG positive rates of different viral encephalitis and viral encephalitis patients not infected with the virus were analyzed by Fisher′s exact probability test. The positive rate of infection with different viruses and non-virus agents was analyzed by Fisher′s exact probability test.@*Results@#The result showed that 80 of 399 samples were positive, and the positive rate was 20.05%. It included 22 cases of enterovirus, 4 cases of influenza A virus, 3 cases of mumps virus, 2 cases of herpes simplex virus type 1, 1 case of herpes simplex virus type 2, 4 cases of EB virus, 7 cases of cytomegalovirus, 7 cases of herpes zoster virus, 8 cases of adenovirus, 14 cases of human herpesvirus type 6. Eight cases had combined viral infection. Eight cases had concurrent infections: 3 cases had enterovirus and herpesvirus type 6 concurrent infection, 1 case had enterovirus and Japanese encephalitis virus concurrent infection and 1 case had herpes simplex virus type 2 and adenovirus, 1 case had influenza A virus herpesvirus type 6, 1 case had mumps virus and herpesvirus type 6, 1 case had mumps virus and herpesvirus type 6, 1 case had herpes simplex virus type 1 and herpes zoster virus concurrent infections. Children with EV viral encephalitis in Hebei Province were highly prevalent in May and June (P=0.016). HHV6 virus encephalitis was more susceptible to infection than non-HHV6 virus (P=0.016); The rate of MRI positive findings in patients with different viral encephalitis was not statistically significant (P>0.05). The result of EEG of different viral encephalitis were P>0.05, which was not statistically significant.@*Conclusions@#EV was the most common pathogen of children with viral encephalitis in Hebei province. Encephalitis caused by influenza A virus cannot be ignored in clinical practice.

Loop-mediated isothermal amplification technique in the diagnosis of hepatitis B virus infection: a Meta-analysis / 中华预防医学杂志

Objective@#To evaluate the diagnostic performance of Loop-mediated isothermal amplification (LAMP) in the diagnosis of Hepatitis B Virus (HBV) infection using Meta-analysis.@*Methods@#Literatures about LAMP in the diagnosis of HBV throughPubMed database of the National Library of Medicine, the EMBASE database of the Dutch Medical Digest, the Cochrane Clinical Trials Database, China Science Periodical Database, CSPD and the China National Knowledge Infrastructure (CNKI) were searched from 2000 to 2016, and the Language limited to Chinese and English. English search terms include: LAMP, Loop-mediated isothermal amplification, HBV, hepatitis B virus; Chinese search terms include: loop-mediated isothermal amplification technology, HBV, hepatitis B virus. The keywords and free words are combined to search the literature, and the references mentioned in the retrieval literature are searched twice. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR), Q index as well as area under summary receiver operating characteristic curve (SROC) were calculated with Stata 12.0 software.@*Results@#A total of 12 literatures with 1 494 cases were included. The pooled sensitivity, specificity, positive likelihood ratio and negative likelihood ratio were 0.922 (95%CI: 0.905-0.937), 0.860 (95%CI: 0.818-0.896), 0.093 (95%CI: 0.048-0.182), and 15.400 (95%CI: 2.003-118.380), respectively. The DOR, area under SROC and Q index were 311.090 (95%CI: 95.841-1 009.800), 0.986 (95%CI: 0.974-0.998) and 0.949 (95%CI: 0.922-0.976), respectively. Deek's test indicates that no publication bias were found (P=0.140).@*Conclusion@#LAMP is worth to be popularized in field tests and primary-level hospitals tests.

Detection of the Zaire Subtype of the Ebola Virus by Isothermal Multiple Self-matching Initiated Amplification / 病毒学报

Given the Ebola outbreak in West Africa and the risks of spread to other regions, a rapid, sensitive and simple method for the detection of the Ebola virus (EBOV) is of great significance for the prevention and control of Ebola. We developed a simple colorimetric isothermal multiple self-matching initiated amplification (IMSA) for rapid detection of the Zaire subtype of the Ebola virus (EBOV-Z). This method employed six primers that recognized seven sites of the EBOV-Z nucleoprotein gene for amplification of nucleic acids under isothermal conditions at 63 degrees C for 1 h. Amplification products were detected through visual inspection of color change by pre-addition of hydroxyl naphthol blue dye. Relative sensitivity was validated by detection of serial tenfold dilutions of virus-like particles containing the partial EBOV-Z nucleoprotein gene and mock clinical sample. Specificity of IMSA was validated by detection of the plasma of 30 healthy volunteers, the dengue virus, and Japanese encephalitis virus. IMSA had comparable sensitivity to Reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and cross-reaction with human plasma or other viruses was not observed. Reverse transcription-isothermal multiple self-matching initiated amplification (RT-IMSA) was also evaluated and compared in parallel with the commercial RT-qPCR kit for detection of EBOV-suspected samples of human blood in Sierra Leone. Sensitivity and specificity of the RT-IMSA was 91.4% and 100%, respectively. These data suggest that RT-IMSA is a valuable tool for the detection of the EBOV with the distinct advantages of simplicity and low cost compared with RT-qPCR.

Colorimetric detection of coxsackievirus A6 by reverse transcription loop mediated isothermal amplification / 中华预防医学杂志

<p><b>OBJECTIVE</b>To develop a simple, rapid and sensitive colorimetric reverse-transcription loop-mediated isothermal amplification (RT-LAMP) for rapid detection of coxsackievirus A6 (CV-A6) based on the colour chang of hydroxy naphthol blue (HNB).</p><p><b>METHODS</b>The method employed a set of six primers that recognized sequences of VP1 gene for amplification of nucleic acid under isothermal conditions at 63 °C for 50 min. The products were detected through visual inspection of color change by the pre-addition of HNB dye. The specificity was validated by detecting a collection of different human enteroviruses. The sensitivity of this assay was evaluated by serial dilutions of RNA molecules from in vitro transcription of CV-A6 VP1 gene, and compared with real-time RT-PCR (rRT-PCR) in parallel. This assay was evaluated with 92 clinical specimens from patients with hand-foot-mouth disease.</p><p><b>RESULTS</b>A positive color (sky blue) was only observed in the preparation of CV-A6, whereas none of the other 23 kinds of human enteroviruses showed a color change. The HNB based RT-LAMP showed a sensitivity of 100 copies/reaction, which was at the same level as that of the rRT-PCR. The result of RT-LAMP in analysis of 92 clinical specimens was consistent with that of the rRT-PCR. The kappa correlation between the two methods was 1 and both of the sensitivity and specificity of the RT-LAMP assay were 100%.</p><p><b>CONCLUSION</b>The established RT-LAMP assay had good specificity and sensitivity and thus demonstrated to be a promising screening tool for CV-A6 infection. It also has the potential to be used in resource-limited clinical sites and field study.</p>

Detection of Middle East Respiratory Syndrome Coronavirus by Reverse-transcription Loop-Mediated Isothermal Amplification / 病毒学报

A simple, rapid and sensitive colorimetric reverse-transcription loop-mediated isothermal amplification (RT-LAMP) was developed for rapid detection of Middle East respiratory syndrome coronavirus (MERS-CoV). The method employed six primers that recognized sequences of a nucleocapsid gene for amplification of nucleic acids under isothermal conditions at 63 degrees C for 60 min. Products were detected through a LA-320c Loopamp Turbidimeter (real-time RT-LAMP) or visual inspection of color change by pre-addition of Hydroxynaphthol Blue dye (visual RT-LAMP). Specificity of RT-LAMP was validated by detection of several human coronaviruses and common respiratory viruses. MERS-CoV real-time RT-LAMP had a linear correlation (R2) of 0.995 at 10(3)-10(6) copies. The limit of detection of real-time RT-LAMP, visual RT-LAMP and quantitative real-time PCR was 500, 1000 and 100 copies/reaction, respectively. The established RT-LAMP assay was demonstrated to be a rapid screening tool for MERS-CoV infection, and could be suitable in resource-limited clinical sites and for field studies.