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ObjectiveTo determine the pathogenic characteristics and genotype of two outbreaks of herpangina in children in Dapeng New District， Shenzhen， in May 2021. MethodsA total of five throat swabs from children in the two outbreaks of herpangina were collected and examined for common enteroviruses by real-time PCR. The VP1 region was further amplified by nested RT-PCR. The CLUSTAL W program in MEGA7 software was used to conduct the alignment and reconstruct a phylogenetic tree. ResultsThe pathogen causing the 2 cluster outbreaks of herpangina was coxsackievirus A4 （CVA4）. The sequences of CVA4 VP1 genes revealed that a nucleotide identity of 92% between the strains in the two outbreaks. The three CVA4 strains isolated in kindergarten A had the closest phylogenetic relationship with that isolated in Shenzhen in 2018（MN840533）， with the nucleotide identity of 98.11%. The two strains in kindergarten B had the closest phylogenetic relationship with CVA4 strain isolated in Sichuan in 2018（MW178763）， with the nucleotide identity of 97.88%. The phylogenetic tree showed that all five CVA4 strains in this study belonged to the C2 genotype. ConclusionThe C2 genotype of CVA4 is the causative agent in both outbreaks of herpangina.
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Objective:To investigate the predominant types of enteroviruses and the characteristics of the VP1 gene of coxsackievirus A4 (CVA4) causing hand, foot and mouth disease (HFMD) in Yunnan Province from 2018 to 2020.Methods:Throat swab and stool samples were collected from HFMD cases and tested by real-time quantitative PCR for nucleic acid detection. The samples positive for enterovirus nucleic acids were used for viral isolation and sent to the National Center for Disease Control and Prevention. The VP1 gene of the isolated strains was sequenced and analyzed.Results:From 2018 to 2020, a total of 21 757 HFMD samples were collected, 16 457 (75.64%) of which were positive for enteroviruses. Altogether 533 strains were isolated from 4 114 positive samples that were selected for viral isolation, including 89 strains of enterovirus 71 (EVA71, 16.70%), 180 strains of coxsackievirus A16 (CVA16, 33.77%), 76 strains of CVA10 (14.26%), 118 strains of CVA6 (22.14%), 26 strains of CVA4 (4.88%) and 44 strains of other types (8.26%). HFMD occurred mainly in children under five years old with higher incidence in males than in females (1.35∶1). The incidence of HFMD reached the peak in the second and third quarters. In Yunnan Province, CVA4 mainly circulated in Qujing and Kunming, and was sporadically detected in Wenshan and Honghe. The VP1 gene was 915 bp in length. Twenty-six CVA4 strains belonged to C2 subtype, which were genetically far from the prototype strain AY421762-HighPoint. Mutations in the VP1 gene were found at multiple sites including 18, 23, 34, 102, 148, 164, 200, 262, 174, 275, 285 and 303. These strains showed 80.4%-99.0% homology in nucleotide sequence and 95.6%-99.0% in amino acid sequence. Nucleotide mutations were mostly synonymous mutations.Conclusions:CVA16, CVA6, EVA71 and CVA10 were the predominant enteroviruses causing HFMD in Yunnan Province from 2018 to 2020. The prevalence of CVA4 was also worthy of attention. CVA4 isolates in Yunnan Province belonged to C2 subtype, mainly circulating in the east and southeast of Yunnan Province and gradually becoming a cocirculating predominant strain. Long-term dynamic monitoring would be of great public health significance for improving the sensitivity of HFMD early warning.
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Objective@#To analyze the genetic characteristics of Coxsackievirus A4 isolated from Taian, 2017-2018.@*Methods@#Sixty throat swab samples of the children who visited Taian Maternal and Child Health Hospital during the year 2017-2018 and were diagnosed as hand, foot and mouth disease, were collected and aseptically inoculated. Fluorescent quantitative PCR analysis was performed using the universal primer for enteroviruses. The high-throughput sequencing was applied to the enterovirus-positive samples, and the full-length genome sequences of the viruses were obtained. Phylogenetic analysis was performed using Mega5.05 and RaxML respectively, and sequence homology and amino acid mutation sites were also analyzed using Mega5.05.@*Results@#Four whole genome sequences of CV-A4 isolated from infants aged 17-19 months old were obtained. Phylogenetic analysis of the full length CV-A4 genomes showed that apart from MG550920/AA/Henan/2016, the remaining CV-A4 strains from China (97.2%), including the four strains from Taian, fell within Group 3. The VP1 genes could be classified into four genotypes and 98.5% of the Chinese strains belonged to genotype D, and the four strains from Taian belonged to D2. It was notable that the Taian isolate A1/Taian is closely related to two strains C179 and C062 from Australia both in the complete genome and the VP1 gene, as well as one strain YT184R isolated from Yantai in 2016 by us. Compared with the prototype CV-A4 strain High Point, 18 amino acid mutations were found in the P1 region.@*Conclusions@#Both phylogenetic trees estimated using the complete genome and the VP1 gene sequences revealed that the four CV-A4 isolates from Taian fell within the same clade with the majority of CV-A4 strains circulating in China. Compared with the prototype CV-A4 strain, several amino acid variations have occurred in the P1 region, which warrants further investigation.
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To analyze the epidemiology,genetic variation and genetic evolution of coxsackievirus A4 (CVA4) in patients with hand,foot and mouth disease in Fujian,the virus isolates were molecular typed and amplified the whole VP1 region by RT-PCR,then the genetic variation and evolution were studied.The results showed that 33 CVA4 cases (8.1％) were confirmed from the 407 non-EV71 non-CVA16 HFMD cases in Fujian Province during 2011 and 2014,accounting for 31 cases in 2012 and 2 cases in 2014.Compared with common characteristics of the HFMD epidemic,no specificity in the distribution of CVA4 cases was found between gender and age groups.Sequence analysis of VP1 nucleotide sequences of Fujian CVA4 isolates showed that the nucleotide and amino acid sequences similarity were 92.6 ％-100 ％ and 95.7 ％-100 ％ respectively,low similarity with the prototype (83.7％-85.4％,96.1％-99.0％) and abroad isolates (82.1％-89.1％,90.4％-99.6％) both in nucleotide and amino acid sequences,high similarity with domestic isolates both in nucleotide and amino acid sequences,with the similarity of 87.9％ 99.2 ％ and 96.1％-100 ％.The results from phylogenetic tree showed that the genetic distance between Fujian CVA4 isolates and the prototype and abroad strains was far,and the genetic distance was close to domestic isolates in China.The distribution of the phylogenetic trees of Fujian CVA4 strains showed multiple branches.Therefore,CVA4 is the major HFMD associated-pathogen other than EV71,CVA 16,CVA6,and CVA10 in Fujian Province from 2011 to 2014.CVA4 strains from Fujian Province is co-circulating and co-evolving with other domestic isolates.There is existence of multiple closely related CVA4 transmission chains in various regions of Fujian.
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To analyze the epidemiology,genetic variation and genetic evolution of coxsackievirus A4 (CVA4) in patients with hand,foot and mouth disease in Fujian,the virus isolates were molecular typed and amplified the whole VP1 region by RT-PCR,then the genetic variation and evolution were studied.The results showed that 33 CVA4 cases (8.1％) were confirmed from the 407 non-EV71 non-CVA16 HFMD cases in Fujian Province during 2011 and 2014,accounting for 31 cases in 2012 and 2 cases in 2014.Compared with common characteristics of the HFMD epidemic,no specificity in the distribution of CVA4 cases was found between gender and age groups.Sequence analysis of VP1 nucleotide sequences of Fujian CVA4 isolates showed that the nucleotide and amino acid sequences similarity were 92.6 ％-100 ％ and 95.7 ％-100 ％ respectively,low similarity with the prototype (83.7％-85.4％,96.1％-99.0％) and abroad isolates (82.1％-89.1％,90.4％-99.6％) both in nucleotide and amino acid sequences,high similarity with domestic isolates both in nucleotide and amino acid sequences,with the similarity of 87.9％ 99.2 ％ and 96.1％-100 ％.The results from phylogenetic tree showed that the genetic distance between Fujian CVA4 isolates and the prototype and abroad strains was far,and the genetic distance was close to domestic isolates in China.The distribution of the phylogenetic trees of Fujian CVA4 strains showed multiple branches.Therefore,CVA4 is the major HFMD associated-pathogen other than EV71,CVA 16,CVA6,and CVA10 in Fujian Province from 2011 to 2014.CVA4 strains from Fujian Province is co-circulating and co-evolving with other domestic isolates.There is existence of multiple closely related CVA4 transmission chains in various regions of Fujian.