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Objective:To investigate the whole genome characteristics of coxsackievirus A4 (CVA4) circulating in Qingdao city.Methods:Four CVA4 isolates circulating in Qingdao city during 2013 to 2015 were selected. Whole genome sequences of these strains were amplified by one-step reverse transcription-polymerase chain reaction (RT-PCR). Sequence alignment and phylogenetic analysis were performed using MEGA7.0 software package. Genetic recombination analysis was performed using similarity plots 3.5.1 software package.Results:Phylogenetic analysis showed that based on the sequences of the whole genome and P1, P2 and P3 regions, HS312/QD/CHN/2013 and HS605/QD/CHN/2014 strains together with the early domestic isolates belonged to the same clade, while FY218/QD/CHN/2015 strain and CV-A4/P1033/2013/China strain collected in Wenzhou in 2013 formed another clade in each phylogenetic tree. HS144/QD/CHN/2014 strain belonged to the same clade as HS312/QD/CHN/2014, HS605/QD/CHN/2014 and the early domestic CVA4 isolates in the phylogenetic tree based on the P1 region, but formed a separate clade in the phylogenetic trees based on the whole genome, P2 region and P3 region. Genetic recombination analysis revealed that there was genetic recombination between HS144/QD/CHN/2014 strain and the CVA2 strain of CV-A2/P373/2013/China isolated in mainland China in 2013 in the region of 2C-3D (5 081-7 301); FY218/QD/CHN/2015 and CV-A4/P1033/2013/China strains were highly homologous and recombination signal sequences were detected in the region of 2A-2B (3 821-4 161) between the two strains and the CVA2 strain of CV-A2/P373/2013/China.Conclusions:The CVA4 isolates circulating in Qingdao city presented obvious genetic diversity at the genome-wide level.
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Objective@#To investigate the etiology spectrum of hand foot and mouth disease (HFMD) and to analyze the molecular characteristics of Coxsackievirus A10 and A6 in Qingdao in 2014.@*Methods@#Throat swabs of HFMD cases were tested for total enteroviruses (EVs), EV-A71, CV-A16, CV-A10 and CV-A6 by multiplex real time RT-PCR. Other EV serotypes were identified through the sequences of partial VP1 gene. The full-length of VP1 gene of CV-A10 and CV-A6 were amplified and sequenced. The sequences were phylogenetically analyzed using MEGA 5.0 software package.@*Results@#A total of 1727 HFMD patients were detected in 2014 and 11serotypes of enteroviruses were identified. EV-A71(38.0%, 410/1078), CV-A16(28.8%, 311/1078), CV-A10(14.1%, 152/1078)and CV-A6(3.2%, 34/1078)were the most dominant pathogen in 2014 in Qingdao. Proportions of CV-A10 in enterovirus infected children varied dramatically in different ages(χ2=15.19, P=0.001), showing a downtrend with age. Proportion of CV-A10 in inpatients was much higher than that in outpatients(χ2=49.1, P <0.001), while 60% of those inpatients showed nervous system damage symptoms, with pathological reflex or disappearance of physiological reflex. Phylogenetic analysis of complete VP1 sequences showed that all CV-A10 strains identied in this study belonged to genotype C, 71.7% of which located in branch C5; all CV-A6 strains belonged to genotype D while 83.3% of which located in branch D5.@*Conclusions@#EV-A71, CV-A16, CV-A10 and CV-A6 were the prevalent pathogens of HFMD in Qingdao in 2014. CV-A10 was more frequently detected in lower age group with HFMD, which can cause damage to nervous system. Strains of branch C5 in genotype C were the dominant strains of CV-A10 circulated in Qingdao in 2014 while strains of branch D5 in genotype D were the major strains of CV-A6.
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Objective@#To illuminate the gene characteristics and clinical characterization of Coxsackievirus B5 (CV-B5) strains isolated from patients with sevre hand, foot and mouth disease (HFMD) in Qingdao city.@*Methods@#A total of 1 844 patients of HFMD were consecutively admitted to Qingdao Women and Children's Hospital from 2013 to 2014. Information of the study population described above was collected retrospectively. The samples were collected from at least 1 site (throat swab, cerebrospinal fluid), which viral nucleic acid extracted and the entire VP1 gene sequences of CV-B5 isolates were amplified and sequenced, then the homology and phylogeny analysis were conducted by MEGA7.0. The prototype Faulkner strain and other VP1 amino acid sequences were derived from the GenBank database.@*Results@#A total of 8 CV-B5 positive cases were obtained, including 4 males and 4 females; 6 severe hospitalized cases and 2 outpatients. The age of 6 hospitalized patients ranged from 3 to 48 months, with a median of 26 months. For the six inpatients, fever, convulsions vomiting, diarrhea and rash were the main clinical manifestation, and all combined with viral encephalitis. Compared with the prototype strain Faulkner, in the VP1 region,the nucleotide and the amino acid homologies was 77.3%-78.8% and 95.5%-97.0% respectively. Five out of the six severe cases with substitution of serine (S) to asparagine (N) at amino acid site 95 in the VP1 region. The sequences of 8 CV-B5 strains were classified into genogroup D.@*Conclusion@#Hand, foot and mouth disease associated with CV-B5 virus infection can result in nervous system involvement and the main complication was viral encephalitis. The CV-B5 strains associated with severe hand, foot and mouth disease had high nucleotide homology and present a certain regional aggregation.
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Objective To investigate the molecular characteristics of coxsackievirus A12 ( CV-A12) and to understand the clinical manifestations of severe hand, foot and mouth disease (HFMD) caused by CV-A12 in Qingdao. Methods Throat swabs of HFMD, herpangina and influenza-like cases from 2011 to 2016 were detected for enteroviruses ( EVs) in Qingdao. Human rhabdomyosarcoma ( RD) and human la-ryngeal carcinoma (Hep-2) cells were used for virus proliferation and CV-A12 strains were identified through a semi-nest RT-PCR. The full-length of VP1 gene of CV-A12 strains was sequenced and phylogenetically an-alyzed using MEGA7. 0 software package. Clinical data of severe HFMD cases positive for CV-A12 were col-lected and analyzed. Results CV-A12-positive HFMD, herpangina and influenza-like cases accounted for 0. 3％(18/6798), 1. 2％(2/169) and 0. 1％(1/676) in Qingdao, respectively. Most of the HFMD caused by CV-A12 in children were mild before 2013 (84. 6％, 11/13), while hospitalized severe cases with neurological symptoms (100％, 5/5) became more common after 2013. Phylogenetic analysis of the VP1 region revealed that CV-A12 strains worldwide could be divided into two genotypes, A and B. All of the CV-A12 strains successfully sequenced in Qingdao from 2011 to 2016 belonged to genotype B, and 88. 9％(16/18) of them belonged to subgenotype B2. All hospitalized severe cases of CV-A12-caused HFMD after 2013 were associated with strains in branch B2b of subgenotype B2. Conclusion CV-A12 was one of the pathogens causing HFMD, herpangina and influenza-like illness in children in Qingdao. Strains of genotype B2 were the predominant CV-A12 strains circulating in Qingdao in recent years. CV-A12-caused HFMD might complicated by nervous system damage.
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Objective To investigate the etiology of hand,foot and mouth disease (HFMD) and to analyze the genetic characteristics of three prevalent enteroviruses in Qingdao in 2015. Methods City-wide surveillance data in 2015 were used to analyze the epidemiological characteristics of HFMD in Qingdao. RNA samples extracted from throat swab of HFMD cases were examined for general enteroviruses (EVs) such as enterovirus 71(EV71), coxsackievirus A16 (CA16) and CA6 by real-time RT-PCR. Full-length VP1 genes of EV-positive specimens were amplified and sequenced. Sequencing results were phylogenetically analyzed using MEGA 7.0 software package. Results A total of 804 patients with HFMD were identified from 1 176 patients in 2015. CA6 (41.4%),EV71 (31.6%) and CA16 (15.3%) were the predominant EVs causing HFMD. Children 5 years of age and under accounted for 80.3% of the 804 HFMD cases. CA6 was responsible for 48.9% of HFMD cases in children under 3 years old. The epidemic subtypes of EV71 and CA16 in Qingdao were C4a and B1b,respectively. Twenty-eight randomly selected CA6 strains were all classified into type A genome. Conclusion CA6, EV71 and CA16 were the prevalent pathogens causing HFMD in Qingdao in 2015. CA6 became the most predominant pathogen,mainly targeting children under 3 years old. C4a remained the prevailing subtype of EV71,while different from the co-prevalence of B1a and B1b subtypes in the past,B1b became the predominant subtype of CA16. CA6 strains circulating in Qingdao in 2015 mainly belonged to type A genome and evolved into multiple smaller branches. However, CA6 strains isolated in Qingdao in 2015 and 2013 located in different branches.
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Objective To investigate the etiology spectrum of hand , foot and mouth disease ( HFMD) and to analysis the molecular characteristics of three predominant human enterovirus stains in Qingdao in 2013.Methods The total enterovirus (EV) strains and strains of EV71, CVA16 and CVA6 in throat swabs of HFMD cases were detected by using multiplex real time RT-PCR.The full-length of the viral VP1 genes of the EV strains were amplified and sequenced .The sequences were phylogenetically analyzed by using the MEGA5.0 software package .Results A total of 841 patients with mild HFMD and 107 patients with serious HFMD were recruited in this study and 64 .3%of them were positive for EV .The predominant pathogens were EV71 (44.8%), CVA6 (28.2%) and CVA16 (9.5%) in 2013.CVA6 replaced CVA16 as the second most common pathogen for HFMD , accounting for 42.7% of all pathogens in children aged less than 3 years and 22.2%of all pathogens in the serious patients .The proportions of CVA6 in the etiology spectrum showed a downtrend along with the increasing age of the patients (P<0.001).Phylogenetic analy-sis of the complete VP1 gene sequences showed that all of the EV 71 strains identified in this study belonged to the subgenotype C4 (evolutionary branch C4a) and all of the CVA16 strains belonged to the subgenotype B1 (evolutionary branches B1a and B1b).There were 6 genogroups (A to F) regarding to the VP1 gene of CVA6 and all of the CVA6 strains identified in this study belonged to genogroups A and D .Among the CVA6 strains isolated in Qingdao in 2013, 83.9% belonged to genogroup A, while the rest 16.1% belonged to genogroup D.66.7%of the CVA6 strains isolated in 2012 belonged to genogroup A, while the rest 33.3%belonged to genogroup D .All of the CVA6 strains isolated from year 2008 to 2011 in Qingdao belonged to genogroup D.Conclusion EV71, CVA6 and CVA16 were the prevalent pathogens responsible for the de-velopment of HFMD in Qingdao in 2013.The proportions of CVA6 strains in the etiology spectrum showed a downtrend with the increasing age in children .C4a was the major subtype of EV71 strains circulating in Qingdao in 2013, while B1a and B1b were the major subtypes of CVA16 strains.The pattern of endemic cir-culation of CVA6 strains showed a trend of changing from genogroup D to A from year 2008 to 2013 .
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Objective To analyze the etiologic spectrum of hand, foot and mouth disease (HFMD) and the molecular characteristics of coxsackievirus A10 (CVA10) strains isolated in Qingdao from year 2010 to 2012.Methods Throat swab specimens were collected from patients with HFMD to detect to-tal enteroviruses ( EVs) , EV71 and CVA16 strains by multiplex real time RT-PCR.The EV-positive speci-mens were further detected by a semi-nested RT-PCR to amplify the sequence of viral genes encoding VP1. The serotypes of EVs were identified based on the sequences of genes encoding VP1.The full-length gene se-quences encoding VP1 of CVA10 isolates were amplified and sequenced. The phylogenetic analysis was con-ducted by using MEGA5.0 software package.Results A total of 1919 outpatients with mild HFMD and 1336inpatients with serious HFMD were recruited in this study .CVA16 strains were the predominant patho-gen for outpatients in year 2010 ( prevalence rate of 53%) and 2012 ( prevalence rate of 73%) .EV71 strains were the predominant pathogen for outpatients in year 2011 ( prevalence rate of 78%) and inpatients in year 2010 ( prevalence rate of 70%) and 2011 ( prevalence rate of 86%) . Some serotypes other than CVA16 or EV71 were the predominant pathogens for inpatients in year 2012 ( prevalence rate 44%) . CVA10 strains were identified in 12 patients with HFMD in year 2010and 17 patients with HFMD in 2012. The full-length gene sequences encoding VP1 of 23 CVA10 isolates were successfully amplified and se-quenced.The phylogenetic analysis showed that the 23 CVA10 isolates all belonged to genotype C and could be further divided into six clades.The genes encoding VP1 of the 23 CVA10 strains shared 97.3% to 1000.%homologies in amino acid sequences.The CVA10 isolates were also similar to their counterparts isolated from other regions during the same period.Conclusion CVA16 and EV71 strains were the preva-lent pathogens of HFMD in Qingdao from year 2010 to 2012, co-circulated with some other serotypes of EVs, especially CVA10 strains.The CVA10 strains belonged to genotype C and shared high homologies among them and their counterparts circulated in other regions during the same period.