Identification and genetic characterization of a recently identified enterovirus C116 in China.

Enterovirus C116 (EV-C116) is a new member of the enterovirus C group which is closely associated with several infectious diseases. Although sporadic studies have detected EV-C116 in clinical samples worldwide, there is currently limited information available. In this study, two EV-C-positive fecal specimens were detected in apparently healthy children, which harbored low abundance, through meta-transcriptome sequencing. Based on the prototypes of several EV-Cs, two lineages were observed. Lineage 1 included many types that could not cause EV-like cytopathic effect in cell culture. Three genogroups of EV-C116 were divided in the maximum likelihood tree, and the two strains in this study (XZ2 and XZ113) formed two different lineages, suggesting that EV-C116 still diffuses worldwide. Obvious inter-type recombination events were observed in the XZ2 strain, with CVA22 identified as a minor donor. However, another strain (XZ113) underwent different recombination situations, highlighting the importance of recombination in the formation of EV-Cs biodiversity. The EV-C116 strains could propagate in rhabdomyosarcoma cell cultures at low titer; however, EV-like cytopathic effects were not observed. HEp-2, L20B, VERO, and 293T cell lines did not provide an appropriate environment for EV-C116 growth. These results challenge the traditional recognition of the uncultured nature of EV-C116 strains and explain the difficulty of clinical detection.

Identification and control of a poliomyelitis outbreak in Xinjiang, China.

BACKGROUND: The last case of infection with wild-type poliovirus indigenous to China was reported in 1994, and China was certified as a poliomyelitis-free region in 2000. In 2011, an outbreak of infection with imported wild-type poliovirus occurred in the province of Xinjiang. METHODS: We conducted an investigation to guide the response to the outbreak, performed sequence analysis of the poliovirus type 1 capsid protein VP1 to determine the source, and carried out serologic and coverage surveys to assess the risk of viral propagation. Surveillance for acute flaccid paralysis was intensified to enhance case ascertainment. RESULTS: Between July 3 and October 9, 2011, investigators identified 21 cases of infection with wild-type poliovirus and 23 clinically compatible cases in southern Xinjiang. Wild-type poliovirus type 1 was isolated from 14 of 673 contacts of patients with acute flaccid paralysis (2.1%) and from 13 of 491 healthy persons who were not in contact with affected persons (2.6%). Sequence analysis implicated an imported wild-type poliovirus that originated in Pakistan as the cause of the outbreak. A public health emergency was declared in Xinjiang after the outbreak was confirmed. Surveillance for acute flaccid paralysis was enhanced, with daily reporting from all public and private hospitals. Five rounds of vaccination with live, attenuated oral poliovirus vaccine (OPV) were conducted among children and adults, and 43 million doses of OPV were administered. Trivalent OPV was used in three rounds, and monovalent OPV type 1 was used in two rounds. The outbreak was stopped 1.5 months after laboratory confirmation of the index case. CONCLUSIONS: The 2011 outbreak in China showed that poliomyelitis-free countries remain at risk for outbreaks while the poliovirus circulates anywhere in the world. Global eradication of poliomyelitis will benefit all countries, even those that are currently free of poliomyelitis.

Poliomyelitis eradication in China: 1953-2012.

BACKGROUND: Poliomyelitis has historically been endemic in China and has been considered an important cause of disability and death. METHODS: We reviewed strategies and measures of poliomyelitis control and eradication from 1953 to 2012. Data from notifiable disease and routine immunization reporting systems and acute flaccid paralysis (AFP) surveillance were analyzed. RESULTS: About 20 000 poliomyelitis cases were reported annually in the prevaccine era. During 1965-1977, live, attenuated oral poliomyelitis vaccine (OPV) was administered to children through annual mass campaigns in the winter, and the number of poliomyelitis cases started to decline. A cold chain system was established during 1982, and OPV coverage increased during the early stage of the Expanded Programme on Immunization, from 1978 to 1988. Between 1989 and 1999, routine immunization was strengthened, supplementary immunization activities (SIAs) were conducted, and the AFP surveillance system was established. China reported a last indigenous poliomyelitis case in 1994 and was certified as free of polio in 2000. To maintain its polio-free status, China kept >90% coverage of 3 doses of OPV, conducted SIAs in high-risk areas, and maintained high-quality of AFP surveillance. China succeeded in stopping the outbreak in Xinjiang in 2011. CONCLUSIONS: China's polio-free status was achieved and maintained through strengthening routine immunization and implementing SIAs and AFP surveillance.

Enhanced surveillance of acute flaccid paralysis following importation of wild poliovirus in Xinjiang Uygur Autonomous Region, China.

BACKGROUND: After being polio free for more than 10 years, an outbreak occurred in China in 2011 in Xinjiang Uygur Autonomous Region (Xinjiang) following the importation of wild poliovirus (WPV) originating from neighboring Pakistan. METHODS: To strengthen acute flaccid paralysis (AFP) surveillance in Xinjiang, "zero case daily reporting" and retrospective searching of AFP cases were initiated after the confirmation of the WPV outbreak. To pinpoint all the polio cases in time, AFP surveillance system was expanded to include persons of all ages in the entire population in Xinjiang. RESULTS: Totally, 578 AFP cases were reported in 2011 in Xinjiang, including 21 WPV cases, 23 clinical compatible polio cases and 534 non-polio AFP cases. Of the 44 polio cases, 27 (61.4%) cases were reported among adults aged 15-53 years. Strengthening AFP surveillance resulted in an increase in the number of non-polio AFP cases in 2011 (148 children < 15 years) compared with 76 cases < 15 years in 2010. The AFP surveillance system in Xinjiang was sensitive enough to detect polio cases, with the AFP incidence of 3.28/100,000 among children < 15 years of age. CONCLUSIONS: Incorporating adult cases into the AFP surveillance system is of potential value to understand the overall characteristics of the epidemic and to guide emergency responses, especially in countries facing WPV outbreak following long-term polio free status. The AFP surveillance system in Xinjiang was satisfactory despite limitations in biological sample collection.

Application of machine learning in the diagnosis of gastric cancer based on noninvasive characteristics.

BACKGROUND: The diagnosis of gastric cancer mainly relies on endoscopy, which is invasive and costly. The aim of this study is to develop a predictive model for the diagnosis of gastric cancer based on noninvasive characteristics. AIMS: To construct a predictive model for the diagnosis of gastric cancer with high accuracy based on noninvasive characteristics. METHODS: A retrospective study of 709 patients at Zhejiang Provincial People's Hospital was conducted. Variables of age, gender, blood cell count, liver function, kidney function, blood lipids, tumor markers and pathological results were analyzed. We used gradient boosting decision tree (GBDT), a type of machine learning method, to construct a predictive model for the diagnosis of gastric cancer and evaluate the accuracy of the model. RESULTS: Of the 709 patients, 398 were diagnosed with gastric cancer; 311 were health people or diagnosed with benign gastric disease. Multivariate analysis showed that gender, age, neutrophil lymphocyte ratio, hemoglobin, albumin, carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125) and carbohydrate antigen 199 (CA199) were independent characteristics associated with gastric cancer. We constructed a predictive model using GBDT, and the area under the receiver operating characteristic curve (AUC) of the model was 91%. For the test dataset, sensitivity was 87.0% and specificity 84.1% at the optimal threshold value of 0.56. The overall accuracy was 83.0%. Positive and negative predictive values were 83.0% and 87.8%, respectively. CONCLUSION: We construct a predictive model to diagnose gastric cancer with high sensitivity and specificity. The model is noninvasive and may reduce the medical cost.

Seroprevalence of Enterovirus A71 and Coxsackievirus A16 in Healthy People in Shandong Province, China.

BACKGROUND: Hand, foot, and mouth disease has become very common in mainland of China in recent years, and enterovirus A71 and coxsackievirus A16 are its major etiologic factors. Here we investigated the seroprevalence of enterovirus A71 and coxsackievirus A16 based on a large group of healthy individuals in Shandong province, China. METHODS: A total of 1378 healthy individuals were tested for serum neutralizing antibodies against enterovirus A71 and coxsackievirus A16 using a micro neutralization test. RESULTS: The overall seroprevalence of enterovirus A71 neutralizing antibodies was 74.75%. It increased significantly from 48.84% in children aged 0-1 years old to 88.64% in those aged 20-29 years (p < 0.01) and decreased to 85.71% in adults > 40 years old with a significant gender-specific difference (p < 0.01). The overall coxsackievirus A16 antibody prevalence was 71.77%. It increased significantly from 39.53% in children aged 0-1 years to 80.68% in those aged 10-19 years (p < 0.01) and decreased to 75.63% in adults >40 years without a gender-specific difference. Nearly 50% of the children <1 year were susceptible to enterovirus A71 infection versus 40% to coxsackievirus A16 infection. Sample collection time and place also played a role in the enterovirus A71 and coxsackievirus A16 positive rates. The overall rates in January were significantly lower than those in April and August (p < 0.01); enterovirus A71 positive rates in Jinan city (capital city of Shandong province) were lower than those in Jining city and Zibo city (p < 0.05); and oxsackievirus A16 positive rates in Jining city were significantly higher than those in Jinan city and Zibo city (p < 0.01). CONCLUSION: There were significant differences among age groups, locations, and time points in the seroprevalence rates of enterovirus A71 and coxsackievirus A16 neutralizing antibodies in healthy people in Shandong province.

Cleaved DNAzyme substrate induced enzymatic cascade for the exponential amplified analysis of L-histidine.

A novel strategy of cleaved DNAzyme substrate induced enzymatic cascade has been devised for the exponential amplified detection of L-histidine. The enzyme strand carries out hydrolytic cleavage of the substrate strand in the presence of L-histidine. The cleaved DNAzyme substrates introduce the polymerase/endonuclease reaction cycles as primers. The L-histidine acts as the activator for enzymatic cascade amplification generating a distinguishable fluorescence enhancement. A good nonlinear correlation (R=0.9994) between fluorescence intensity and the logarithm of the L-histidine concentration is obtained over the range from 50 nM to 1.0 mM. The detection limit was estimated as 30 nM. This efficient amplification of the fluorescence signal is attributed to the L-histidine induced cooperation of Klenow Fragment polymerase (exo(-)) and Nb.BbvCI endonuclease reaction. The activation of such enzymatic cascades through analyte-DNAzyme interactions has a substantial impact on the development of exponential amplified DNAzyme sensors.

Enzymatic cascade based fluorescent DNAzyme machines for the ultrasensitive detection of Cu(II) ions.

A novel enzymatic cascade based fluorescent DNAzyme machine has been developed for the amplified detection of copper (Cu(2+)) ions. This is the first attempt to carry out the combination of the self-cleaving DNAzyme and the polymerase/endonuclease reaction cycles involving cleaved substrate extension. In the presence of Cu(2+) ions, the enzyme strand carries out catalytic reactions to hydrolytic cleavage of the substrate strand. The cleaved DNAzyme substrates act as primers and trigger the Klenow Fragment polymerization. Nb.BbvCI endonuclease cuts the double-stranded niking site and thus opens a new site for a new replication. The replication regenerates the complete dsDNA to initiate another cycle of nicking, polymerization and displacement. Finally the fluorescence dye, SG, inserts into the DNA double helix to generate a distinguishable fluorescence enhancement. The Cu(2+) ions act as the activator for enzymatic cascade amplification generating multiple duplex structures in the nascent product. An increasing fluorescence is observed with increasing Cu(2+) ions concentration. A good nonlinear correlation (R=0.9997) was obtained between fluorescence intensity and the cubic logarithm of the Cu(2+) ions concentration over the range 0.50-200 nM. This nonlinear response phenomenon results in an efficient improvement of the sensitivity of our current proposed assay. The activation of such enzymatic cascades through analyte-DNAzyme interactions is not only valuable to activate the cooperation of enzyme networks, but also has a substantial impact on the development of amplified DNAzyme sensors.

[Epidemiology of hand, foot, and mouth disease and genetic characterization of enterovirus A71: a survey from 2007 to 2012 in Linyi of Shandong Province, China].

To investigate the epidemiology of hand, foot, and mouth disease (HFMD) and the genetic characteristics of enterovirus A71 (EV-A71) in Linyi of Shandong Province, China during 2007-2012. The number of reported HFMD cases were obtained from the National Notifiable Disease Reporting System (NNDRS) were analyzed by descriptive epidemiology method; the VP1 region of EV-A71 isolated from HFMD patients in Linyi was amplified and sequenced. Finally, the genetic variability and phylogenecity of VP1 sequences of EV-A71 were analyzed by MEGA 5.0. The results showed that HFMD incidence was reported in each year from 2007 to 2012 in Linyi, and the highest incidence and mortality were reported in 2009, when there were total 14697 cases and 9 of death. The reported incidence was 140.28/100000, and the mortality was 0.086/100000. The peak incidence usually occurred between April and July, and the summit occurred in May. Scattered children accounted for 77.37%-92.00% of all cases. The peak age was 2.5 years during 2007-2009 and 1.5 years during 2010-2012. A total of 1365 laboratory-confirmed HFMD cases were reported in the 6 consecutive years, accounting for 2.98% of the gross number. Among these reports, the ratio of EV-A71 was 44.18%, and the ratio of coxsackievirus A16 (CVA16) was 46.59%. All EV-A71 strains isolated in Linyi during 2007-2012 belonged to the C4a evolutionary branch of C4 genotype. In conclusion, HFMD outbreaks occurred every year in Linyi during 2007-2012. Incidence varied significantly among different counties. The peak incidence in each year lasted from April to July. Most of the patients were children under 3 years of age, and scattered children took the highest proportion. Co-circulation of EV-A71 and CVA16 was the major cause of HFMD in each year. Since the first report of HFMD prevalence caused by EV-A71 (C4a) in 2007, the virus has been prevalent continuously in Linyi for 6 years.

Sero-survey of polio antibodies during wild poliovirus outbreak in southern Xinjiang Uygur Autonomous Region, China.

BACKGROUND: After being polio free for more than 10 years, an outbreak following importation of wild poliovirus (WPV) was confirmed in Xinjiang Uygur Autonomous Region, China, in 2011. METHODS: A cross-sectional study was conducted prior to supplementary immunization activities (SIAs), immediately after the confirmation of the WPV outbreak. In selected prefectures, participants aged ≤ 60 years old who visited hospitals at county-level or above to have their blood drawn for reasons not related to the study, were invited to participate in our study. Antibody titers ≥ 8 were considered positive. RESULTS: Among the 2,611 participants enrolled, 2,253 (86.3%), 2,283 (87.4%), and 1,989 (76.2%) were seropositive to P1, P2 and P3 respectively, and 1744 (66.8%) participants were seropositive to all the three serotypes. Lower antibody seropositivities and geometric mean titers were observed in children <1 year of age and in adults aged 15-39 years. CONCLUSION: Serosurveys to estimate population immunity in districts at high risk of polio importation might be useful to gauge underlying population immunity gaps to polio and possibly to guide preparedness and response planning. Consideration should be given to older children and adults during polio risk assessment planning and outbreak response.

[Epidemiology and etiology of hand-foot-and-mouth disease in Hainan, 2010].

To reveal the epidemiological and pathogenic characteristics of Hand-foot-and-mouth disease (HFMD) in Hainan province in 2010, epidemiology data of HFMD reporting cases were analyzed, clinical specimens from 1346 HFMD cases were collected for enterovirus (EV) detection. Viral isolation was performed for EV nucleic acid positive samples. Complete VP1 encoding region of EV71 were sequenced and analyzed with Sequencher (version 5.0) and MEGA software (version 5.0). The epidemiology data showed that all 18 prefectures in Hainan had reporting cases during 2010, with higher incidence in the northeast; and the children less than 4 years old accounted for the majority of the suffered; the epidemic reached peak during September to October, which was different from other Provinces in China. The laboratory results indicated that EV71 and CA16 were identified as the major causative pathogens in Hainan in 2010, however, EV71 infection was absolutely dominant among severe and fatal cases. In addition, some HFMD cases were identified associated with other serotypes of EV infections. Molecular epidemiological analysis showed that all the EV71 strains belonged to C4a evolutionary branch, which is the dominant evolutionary branch in China in recent years, and at least three transmission chains existed. This study has an important information in clarifying the characteristics of epidemics and transmission of HFMD in Hainan, and to provide the guidance for HFMD prevention and control in the future.

[Rash and fever illness caused by herpes simplex virus type 1 needs to be distinguished from hand, foot and mouth disease].

An epidemic of rash and fever illnesses suspected of hand, foot and mouth disease (HFMD) occurred in Gansu Province of China in 2008, laboratory tests were performed in order to identify the pathogen that caused this epidemic. Eight clinical specimens collected from the 4 patients (each patient has throat swab and herpes fluid specimens) with rash and febrile illness, were inoculated onto RD and HEp-2 cells for virus isolation, and the viral nucleic acid was then extracted with the positive virus isolates, the dual-channel real-time reverse transcript-polymerase chain reaction (RT-PCR) was performed to detect the nucleic acid of human enterovirus (HEV) in the viral isolates at the same time. For the viral isolates with the negative results of HEV, a sequence independent single primer amplification technique (SISPA) was used for "unknown pathogen" identification. Totally, 6 viral isolates were identified as herpes simplex virus type 1 (HSV-1). Comprehensive analyses results of the clinical manifestations of the patients, epidemiological findings and laboratory test indicated that this epidemic of rash and febrile illness was caused by HSV-1. The differences among the gG region of 6 HSV-1 isolates at nucleotide level and amino acid level were all small, and the identities were up to 98. 8% and 97.9%, respectively, showing that this outbreak was caused by only one viral transmission chain of HSV-1. HSV-1 and other viruses that cause rash and febrile illnesses need differential diagnosis with HFMD. The etiology of rash and febrile illness is sometimes difficult to distinguish from the clinical symptoms and epidemiological data, the laboratory diagnosis is therefore critical.

[Analysis of genetic characteristics of type II non-wild poliovirus in mainland China, 2010].

To study the genetic characteristics of 123 type II non-wild polioviruses isolated from acute flaccid paralysis (AFP) cases in mainland China in 2010, provide the scientific basis for maintaining the "polio-free" status, and the switching use of polio vaccine for China. VP1 gene was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and the PCR products were then sequenced. The sequence results were analyzed with Sequencher 4.8, BioEdit 7.0.9 and MEGA 5.0. Of 65 strains, nt2909 was found to be a mutation hotspot, and also a neurovirulence determinant in VP1 region. During 2010, two vaccine-derived polioviruses (VDPVs) were isolated from Yunnan province, China and no wild poliovirus (WPV) was isolated. The epidemiological studies and laboratory results of the two VDPVs showed that they were newly discovered VDPVs because of the genetic difference from other VDPVs strains isolated in the world, implying the sensitive poliovirus surveillance network could timely detect the transmission of VDPVs and the importation of WPV.

[Transmission and prevalence patterns of C4a evolutionary lineage of human enterovirus 71 circulating in mainland China, 2008-2010].

OBJECTIVE: To understand the evolutionary relationship between the C4a evolutionary lineage of human enterovirus 71 (HEV71) strains circulating in mainland of China during 2008-2010 and 2008 Fuyang strains and study the prevalence and transmission patterns of 2008 Fuyang strains. METHODS: Download all the complete VP1 ( > or = 891 bp) or approximate complete VP1 (> or = 876 bp) gene nucleotide sequences from GenBank of HEV71 strains circulating in Mainland of China during 2008-2010. And analyze the phylogenetic relationship between Fuyang strains and other provinces' strains using the MEGA software, version 5.0. RESULTS: All of the HEV71 isolates circulating in Mainland of China during 2008-2010 were clustered into evolutionary lineage C4a except for eight strains grouped in the genotype A and one isolate belongs to evolutionary lineage C4b; the homology analysis showed there were 96.5%-100% identity between C4a viruses circulating in mainland China during 2008-2010 and 2008 Fuyang strains, and they were evolved from C4b viruses of 1998. The transmission chains of Fuyang strains were mainly transmitted in Guangdong, Jiangsu, Shanghai, Hunan, Shandong provinces. CONCLUSION: The predominant viruses circulating in Mainland of China during 2008-2010 were evolutionary lineage C4a of human Enterovirus 71; Fuyang transmission chains mainly distributed in southern of China and the Central China around Anhui provinces.

Visual detection of human enterovirus 71 subgenotype C4 and Coxsackievirus A16 by reverse transcription loop-mediated isothermal amplification with the hydroxynaphthol blue dye.

A sensitive reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for rapid visual detection of human enterovirus 71 subgenotype C4 (EV71-C4) and Coxsackievirus A16 (CVA16) infection, respectively. The reaction was performed in one step in a single tube at 65°C for 60 min with the addition of the hydroxynaphthol blue (HNB) dye prior to amplification. The detection limits of the RT-LAMP assay were 0.33 and 1.58 of a 50% tissue culture infective dose (TCID(50)) per reaction based on 10-fold dilutions of a titrated EV71 or CVA16 strain, respectively. No cross-reaction was observed with Coxsackievirus A (CVA) viruses (CVA2, 4, 5, 7, 9, 10, 14, and 24), Coxsackievirus B (CVB) viruses (CVB1,2,3,4, and 5) or ECHO viruses (ECHO3, 6, 11, and 19). The assay was further evaluated with 47 clinical stool specimens diagnosed previously with EV71, CVA16 or other human enterovirus infections. Virus isolates from stool samples were confirmed by virus neutralization testing and sequencing. RT-LAMP with HNB dye was demonstrated to be a sensitive and cost-effective assay for rapid visual detection of human EV71-C4 and CVA16.

[Genetic characterization of poliovirus isolates from environmental sewage surveillance in Shandong, 2010].

To investigate the genetic characteristics of poliovirus isolates from environmental sewage surveillance in Shandong province, we collected sewage samples in Jinan and Linyi City. Serotyping and VP1/ 3D sequencing were performed on polioviruses isolated from the concentrated sewage samples, and VP1 mutation and recombination were analyzed. Thirty-two of sewage samples were collected, and polioviruses were detected in 10 of the samples with a positive rate of 31.3%. Eighteen Sabin strains were isolated including three type 1, nine type 2, and six type 3 polioviruses, and the number of nucleotide substitutions in VP1 coding region varied from 0 to 4. Recombination was found in three Sabin 2 and four Sabin 3 polioviruses. Analysis of neurovirulence sites of VP1 revealed that one Sabin 1 vaccine strain had a nucleotide change of A to G at nt 2749, one Sabin 2 strain had a nucleotide change of A to G at nt 2908, three Sabin 2 strains had a nucleotide change of U to C at nt 2909, and all six Sabin 3 strains had a nucleotide change of C to U at nt 2493. Poliovirus vaccine strains could be isolated from environmental sewage with a high rate of gene recombination and back mutation of neuvirulence-associated sites. None of wild-type poliovirus or vaccine-derived poliovirus was detected.

[Identification and genetic characteristics of five non-polio enteroviruses (NPEVs) multiplicated on L20B cell line].

OBJECTIVE: To identify and describe the genetic characteristics of non-polio enteroviruses (NPEVs) which could multiplicated on L20B cell line, and discuss the impact to isolation rate of polioviruses. METHODS: 5 L20B positive isolates were collected from stool samples of patient with acute flaccid paralysis (AFP) and health children in Guangxi Zhuang autonomous region and Ningxia Hui autonomous region. These isolates were analysed using VP4 nucleotide sequencing method. The completed VP, coding regions were amplified and sequenced. Finally, phylogenetic tree were constructed base on completed VP1 coding regions sequences of these L20B positive isolates and those downloaded form GenBank database. RESULTS: The 5 NPEVs were all identified as coxsackieviruses group A (CVA). Among them, 1 was identified as CVA4, 1 was identified as CVA8 and 3 were identified as CVA10, and all of them belonged to human enterovirus species A (HEV-A). Nucleotide homology analysis and phylogenetic analysis base on completed VP1 coding regions sequences showed that all these 3 serotypes of NPEVs clustered independently, and they were all native circulated viruses in mainland China. CONCLUSIONS: 5 NPEVs in this study belonged to HEV-A, covered 3 serotypes, CVA4, CVA8 and CVA10. Due to the high sensitivity of primarily inoculation of poliovirus onto L20B cell, the isolation rate of polioviruses could not be affected so much. Hand, foot, and mouth disease (HFMD) outbreaks in mainland China in recent years, and it was found that HEV-A is also pathogen of HFMD. Identification of these viruses have current significance to differential diagnosis of poliovirus infection and HFMD control and prevention.

[Evaluation on running status of Chinese Polio Laboratories Network in 2008].

OBJECTIVE: In order to evaluate the running status and provide the laboratory data for maintaining polio-free status in China, the virology surveillance database of Chinese Polio Laboratories Network (not include Hong Kong, Macao, and Taiwan)in 2008 were analyzed. METHODS: The case investigation data of Acute Flaccid Paralysis(AFP)cases reported by 31 provinces (municipal, autonomous regions) through EPI surveillance information management system and the database of National Polio Laboratory (NPL) were analyzed, and the indicators of running status of Chinese Polio Laboratories Network were evaluated. RESULTS: 10,116 stool samples were collected from 5116 AFP cases by Chinese Polio Laboratories Network in 2008, and viral isolation and identification of all stool samples were done according to 4th World Health Organization (WHO) Polio Laboratory Manual. The rate of viral isolation and identification performed within 28d was 94.9%. 189 polioviruses (PV) and 597 of non-polio enteroviruses (NPEV) were isolated from AFP cases, the isolatien rates were 3.72% and 11.74% respectively. 251 polio positive isolates were sent to NPL from 31 provincial polio laboratories. There were 318 single serotype PVs were performed VPI sequencing. And no wild polioviruses and Vaccine-derived Polioviruses (VDPVs) were found in 2008. NPL passed the proficiency test and got full accreditation for on-site review by WHO experts in 2008. All 31 provincial Polio laboratories passed the proficiency test with the same panel as NPL, and 13 provincial Polio laboratories joined and passed the on-site review by WHO experts. CONCLUSION: The running status of Chinese Polio Laboratories Network was good, polio-free status was maintained in China in 2008. The Chinese polio laboratories network running is normaly, the laboratory surveillance system was sensitive and laboratory data were provided for maintaining the polio-free status in China.

[Genetic characterization of coxsackievirus A16 isolated in Ningxia Hui Municipality in 2008].

OBJECTIVE: To study the genetic characterization of coxsackievirus A16 (CVA16) strains isolated during an epidemic of hand, foot, and mouth disease (HFMD) in Ningxia Hui Municipality in 2008. METHODS: Clinical samples were collected from HFMD patients in Ningxia Hui Municipality and CVA16 strains were isolated by viral isolation methods. Reverse transcription-polymerase chain reactions (RT-PCR), specific for CVA16 were performed with these CVA16 strains. Entire VP1 coding region amplification and sequencing were then performed and finally phylogenetic tree was constructed among Ningxia CVA16 strains and CVA16 representative strains of known genotypes and subgenotypes. RESULTS: 70 Ningxia CVA16 strains were isolated from HFMD patients in Ningxia in 2008 and the homology of nucleotide and amino acid were 90.8%-100.0% and 98.9% - 100.0%, respectively. Phylogenetic characteristics of the strains reconfirmed that they could be divided into two distinct genotypes-A and B. Genotype B could be further divided into the subgenotypes B1 and B2, while all the 70 Ningxia CVA16 strains belonged to the co-circulated clusters B1a and B1b within subgenotype B1, which belonged to 2 viral transmission chains. CONCLUSION: Our results indicated that subgenotype B1 CVA16 strains continued to circulate over a wide geographic area of mainland China since the first reported episode in Shenzhen city in 1999. Like other CVA16 strains isolated elsewhere in China, both B1a and B1b evolution branches were co-circulating in Ningxia Hui Municipality. Based on the close phylgenetic and chronological relationship with CVA16 isolated in other countries and regions near China. Our data confirmed that these strains co-evolved and co-circulated with those from neighboring countries and regions.

[Analysis on identification and genetic character of type I vaccine-derived poliovirus in Shanxi province in 2007].

OBJECTIVE: To describe the source of vaccine-derived poliovirus (VDPV) and the effect on local polio-free status, the VP1 coding region was sequenced and analyzed for type I VDPV in Shanxi province in 2007. METHOD: The virus isolation was performed to double stool specimens from one case acute flaccid paralysis (AFP) patient. VP1 coding region of the isolated stain was sequenced and analyzed. The phylogenetic tree was constructed based on VP1 region sequence between Shanxi strains and other type I VDPVs. RESULT: 2 type I + II +III strains were isolated from double stool specimens from the AFP patient in Shanxi Province in 2007. VP1 sequencing of the two stains revealed > 1.0% divergence from the VP1 region of P I /Sabin vaccine strain. According to WHO criteria, the two stains were identified as type I vaccine-derived poliovirus (VDPV). Phylogenetic analysis based on VP1 coding sequence showed that the evolution distance of Shanxi type I VDPV was far away from other VDPVs detected in China. Moreover, no evidence supported the AFP patient as immunodeficiency patient. So Shanxi type I VDPVs were classified into ambiguous VDPV(aVDPV). CONCLUSION: Considering the genetic character for Shanxi type I VDPV and the local OPV coverage, we highly suspected that an immunodeficiency patient in local area who long-term excreted VDPVs existed and resulted in the patient infection of VDPV in Shanxi in 2007. In the post era of polio eradication, the detection and management for the possible existing patient of long-term excretion VDPV should be strengthened.