[Analysis of the complete genome characterization of 11 human astrovirus strains in Shandong Province].

Objective: To study the complete genome characterization of Human Astrovirus (HAstV) in Shandong Province. Methods: Stool samples from acute flaccid paralysis (AFP) surveillance in Shandong Province from 2020 to 2022 were collected, and HAstV nucleic acid was examined by real-time quantitative PCR (qPCR). Next-generation sequencing (NGS) was conducted for the positive samples to obtain complete genome sequences and identify the genotype. Homology comparison and phylogenetic analysis were performed by using BioEdit and Mega software. Results: A total of 667 samples were examined by qPCR, of which 14 were HAstV-positive (2.1%), including HAstV-1 (n=6), MLB1 (n=6), MLB2 (n=1), and VA2 (n=1). The complete genome sequences were obtained from 11 samples. The six HAstV-1 sequences of this study had 98.2% to 99.9% nt similarities with each other and 87.6% to 98.6% with those from other regions. The four MLB1 sequences of this study had 99.1% to 99.9% nt similarities with each other and 92.2% to 99.4% with those from other regions. The VA2 sequence of this study had 96.0% to 96.3% nt similarities with those from other regions. Phylogenetic analysis based on ORF2 region showed that the local HAstV-1 sequences were most closely related to Japanese strains, and had distinct topology with phylogenies based on ORF1a and ORF1b regions. Conclusion: The complete genome sequences of 11 HAstV strains are obtained, and the VA2 complete genome is found.

[Analysis on the infection source of the first local cluster epidemic caused by the VOC/Gamma variant of SARS-CoV-2 in China].

Objective: To investigate a SARS-CoV-2 epidemic reported in Rongcheng City, Weihai, Shandong Province. Methods: The SARS-CoV-2 nucleic acid positive patients and their close contacts were investigated, and the whole genome sequencing and genetic evolution analysis of 9 variant viruses were carried out. An infection source investigation and analysis were carried out from two sources of home and abroad, and three aspects of human, material and environment. Results: A total of 15 asymptomatic infections were reported in this epidemic, including 13 cases as employees of workshop of aquatic products processing company, with an infection rate of 21.67% (13/60). Two cases were infected people's neighbors in the same village (conjugal relation). The first six positive persons were processing workers engaged in the first process of removing squid viscera in the workshop of the company. The nucleic acid Ct value of the first time were concentrated between 15 and 29, suggesting that the virus load was high, which was suspected to be caused by one-time homologous exposure. The whole genome sequence of 9 SARS-CoV-2 strains was highly homologous, belonging to VOC/Gamma (Lineage P.1.15). No highly homologous sequences were found from previous native and imported cases in China. It was highly homologous with the six virus sequences sampled from May 5 to 26, 2021 uploaded by Chile. The infection source investigation showed that the company had used the squid raw materials captured in the ocean near Chile and Argentina from May to June 2021 over the last 14 days. Many samples of raw materials, products and their outer packages in the inventory were tested positive for nucleic acid. Conclusion: This epidemic is the first local epidemic caused by the VOC/Gamma of SARS-CoV-2 in China. It is speculated that the VOC/Gamma, which was prevalent in South America from May to June 2021, could be imported into China through frozen squid.

[Basic immunization of vaccines is fundamental, and booster immunization is the guarantee: Booster immunization and its public health value].

Booster immunization is the following vaccination after a period of vaccine primary immunization schedule in order to maintain immunity against a certain pathogen. In this article, the immunological mechanism of booster immunization is elaborated, and the effectiveness and public health value of booster immunization for common vaccines is discussed. Subsequently, three hot issues of general concern in booster immunization are addressed, and the public health viewpoint that "Primary immunization of vaccines is fundamental, and booster immunization is the guarantee" is emphasized, so as to raise awareness of the importance and necessity of booster immunization as well as to provide scientific evidences for vaccine immunization practice.

[Genetic characteristics of varicella zoster virus in Shandong province from 2020 to 2021].

Objective: To investigate the genetic characteristics of varicella zoster virus (VZV) in Shandong province from 2020 to 2021. Methods: From April 2020 to December 2021, 85 herpes fluid samples from suspected varicella patients in Shandong province were collected. The qPCR was used to detect viral DNA and screen suspected samples. Six single nucleotide polymorphisms (SNPs) of ORF22 fragment and ORF38 fragment in positive samples were examined via PCR and Sanger sequencing to identify the viral genotypes. Four SNPs of ORF38 and ORF62 were examined to identify the vaccine and wild-type strains. The sequences were analyzed with Sequencher and MEGA7 software, using the VZV reference strain sequences from GenBank. Results: In the 85 samples suspected of varicella, 80 were VZV positive and wild-type strains belonging to Clade 2. Compared with clade 2 representative strains, the nucleotide and amino acid similarities of ORF22 fragment were 99.5%-100% and 98.5%-100%, respectively. SD20-1, SD20-5, SD20-6, SD20-8, SD20-9, SD20-10, SD20-11, SD20-12, SD20-13, SD20-30 and SD20-31 had a A➝G nucleotide mutation at 37990, causing amino acid change from glutamine to arginine. SD21-1 had a C➝A nucleotide mutation at 38059, causing threonine to asparagine during coding. Conclusions: From 2020 to 2021, all VZV strains in Shandong province are the wild-type strains belonging to Clade 2.

[Molecular epidemiological characterization of group A rotavirus in domestic sewage in Jinan from 2016 to 2018].

Objective: To understand the detection of group A rotavirus (RVA) in domestic sewage and its molecular epidemiological characteristics, and further explore the feasibility and necessity of RVA environmental surveillance. Methods: From 2016 to 2018, we collected domestic sewage samples monthly in Jinan city, and concentrated them via anion membrane adsorption-elution method. Then RNA extraction and RVA VP7 and VP4 coding region RT-PCR amplification were performed. After purification, TA cloning and sequencing, homology analysis and phylogenetic analysis were conducted on the obtained sequences. Results: RVA G gene was detected in 31 of the 36 sewage samples (86.1% detection rate); RVA P genotype was detected in 33 samples (91.7% detection rate). A total of 536 RVA sequences were obtained, of which 225 G-type sequences belonged to 6 genotypes, and the G9 accounted for 92.4% (208/225); 311 P-type sequences were obtained, which belonged to 4 genotypes. The dominant P[8] accounted for 50.1% (156/311), followed by P[4] with 41.8% (130/311). Phylogenetic analysis shows that there were multiple transmission chains circulating in the dominant genotypes G9 and P[8]. Conclusion: The genotype, homology, and phylogenetic characteristics of sequences obtained from domestic sewage in Jinan area were described, which further confirmeing that RVA environmental surveillance is not feasible but also necessary.

[Rotavirus gastroenteritis and its vaccination].

Rotaviruses infection is one of the main causes of diarrhea among infants and children in the world, resulting in rotavirus gastroenteritis, which is very harmful and has caused a huge disease burden and no specific drug treatment. This paper reviews the rotavirus etiology, epidemiological characteristics, disease burden of rotavirus gastroenteritis and rotavirus vaccines. RV in group A is the main cause of acute gastroenteritis in infants, people at all ages are generally susceptible to RV, 3 to 24 months infants have the most severe symptoms of diarrhea, RVGE epidemic is seasonal and peaks in winter, increasing RV vaccination can reduce the incidence and mortality of rotavirus diarrhea in infants to reduce the burden of corresponding disease. This article focuses on RV vaccines currently in use and their effect on preventing RV infection, and put forward thoughts and suggestions on technical issues related to the application of RV vaccine in China. Provide support for improving the RV vaccine immunization strategy and Chinese-specific immunization strategy for eventually incorporating RV vaccine into the national child immunization program.

[Etiologic surveillance and analysis of acute meningitis and encephalitis syndrome in Jinan city in 2013-2016].

Objective: To characterize the etiology and epidemiological characteristics of the acute meningitis and encephalitis syndrome (AMES) in Jinan city in 2013-2016. Methods: The epidemiological data, clinical diagnosis, serum and cerebrospinal fluid (CSF) specimens were collected from 3 577 AMES cases in 6 sentinel hospitals in Jinan city in 2013-2016. Samples of all cases were made sero-diagnosis for Immunoglobulin (Ig) M antibody to Japanese encephalitis virus (JEV) and negative cases of JEV for enterovirus (EV), mumps virus (MuV) and herpes simplex virus (HSV) by enzyme-linked immunosorbent assay (ELISA). Virus isolation and molecular identification were performed. Positive rates were analyzed by Chi-square test. Results: In 2013-2016, the positive rates of JEV, EV, MuV and HSV were 9.0% (322/3 577 cases), 22.1% (643/2 916 cases), 9.9% (289/2 916 cases), 26.9% (783/2 916), respectively. Of these, the positive rates of JEV were 32.9% (261/794), 1.2% (14/1 175), 1.0% (8/807) and 4.9% (39/801 cases); EV: 19.5% (91/466), 35.1% (342/974 cases), 15.5% (115/743) and 13.0% (95/733); MuV: 9.2% (43/466), 14.4% (140/974), 9.0% (67/743) and 5.3% (39/733). HSV: 35.4% (165/466), 38.5% (375/974), 25.7% (191/743) and 7.1% (52/733). There were significant differences in positive rates of 4 kinds of viruses in 2013-2016 (P<0.001). A total of 81 EV strains belonging to 8 serotypes were isolated from 1 020 CSF specimens. The positive rates were 4.8% (6 cases), 13.1% (55 cases), 4.1% (7 cases) and 4.2% (13 cases) from 2013 to 2016. Coxsackievirus (CV) B5, echovirus (E) 6 and E30 accounted for 46% (37 isolates), 22% (18 isolates) and 21% (17 isolates) of all strains. Conclusion: The AMES cases in Jinan city in 2013-2016 were mainly caused by HSV, EV, MuV, JEV. CVB5, E6 and E30 were the dominant serotypes of EV associated with AMES cases in Jinan city.