Shuangli Zhu

An emerging recombinant human enterovirus 71 responsible for the 2008 outbreak of hand foot and mouth disease in Fuyang city of China.

Hand, foot and mouth disease (HFMD), a common contagious disease that usually affects children, is normally mild but can have life-threatening manifestations. It can be caused by enteroviruses, particularly Coxsackieviruses and human enterovirus 71 (HEV71) with highly variable clinical manifestations. In the spring of 2008, a large, unprecedented HFMD outbreak in Fuyang city of Anhui province in the central part of southeastern China resulted in a high aggregation of fatal cases. In this study, epidemiologic and clinical investigations, laboratory testing, and genetic analyses were performed to identify the causal pathogen of the outbreak. Of the 6,049 cases reported between 1 March and 9 May of 2008, 3023 (50%) were hospitalized, 353 (5.8%) were severe and 22 (0.36%) were fatal. HEV71 was confirmed as the etiological pathogen of the outbreak. Phylogenetic analyses of entire VP1 capsid protein sequence of 45 Fuyang HEV71 isolates showed that they belong to C4a cluster of the C4 subgenotype. In addition, genetic recombinations were found in the 3D region (RNA-dependent RNA polymerase, a major component of the viral replication complex of the genome) between the Fuyang HEV71 strain and Coxsackievirus A16 (CV-A16), resulting in a recombination virus. In conclusion, an emerging recombinant HEV71 was responsible for the HFMD outbreak in Fuyang City of China, 2008.

An outbreak of hand, foot, and mouth disease associated with subgenotype C4 of human enterovirus 71 in Shandong, China.

BACKGROUND An outbreak of hand, foot, and mouth disease (HFMD) included 1149 people in Linyi City, Shandong Province, China, in 2007: three children died. OBJECTIVES To characterize the pathogens responsible for this outbreak and to analyze their genetic features. STUDY DESIGN A total of 233 clinical specimens were collected from 105 hospitalized patients, including 11 patients with severe HFMD. Virological investigations (direct RT-PCR, viral isolation and molecular identification) and phylogenetic analysis were performed. RESULTS Human enterovirus 71 (HEV71) was the main pathogen that caused this outbreak, based on clinical manifestations, epidemiological data, and laboratory results. Phylogenetic analysis indicated that the Shandong HEV71 isolates belonged to 3 lineages in subgenotype C4. Subgenotype C4 could be further divided into two clusters (C4a and C4b), which corresponded to two time periods. Cluster C4a HEV71 has been the predominant virus circulating in mainland China in the past 5 years. CONCLUSIONS The 2007 HFMD outbreak was mainly caused by HEV71 subgenotype C4 with 3 transmission chains. This virus has been continuously circulating in China since 1998. The Shandong strains co-evolved with isolates from other provinces in mainland China and neighboring countries.

The persistent circulation of enterovirus 71 in People's Republic of China: causing emerging nationwide epidemics since 2008.

Emerging epidemics of hand-foot-and-mouth disease (HFMD) associated with enterovirus 71 (EV71) has become a serious concern in mainland China. It caused 126 and 353 fatalities in 2008 and 2009, respectively. The epidemiologic and pathogenic data of the outbreak collected from national laboratory network and notifiable disease surveillance system. To understand the virological evolution of this emerging outbreak, 326 VP1 gene sequences of EV71 detected in China from 1987 to 2009 were collected for genetic analyses. Evidence from both traditional and molecular epidemiology confirmed that the recent HFMD outbreak was an emerging one caused by EV71 of subgenotype C4. This emerging HFMD outbreak is associated with EV71 of subgenotype C4, circulating persistently in mainland China since 1998, but not attributed to the importation of new genotype. Originating from 1992, subgenotype C4 has been the predominant genotype since 1998 in mainland China, with an evolutionary rate of 4.6∼4.8×10−3 nucleotide substitutions/site/year. The phylogenetic analysis revealed that the majority of the virus during this epidemic was the most recent descendant of subgenotype C4 (clade C4a). It suggests that the evolution might be one of the potential reasons for this native virus to cause the emerging outbreak in China. However, strong negative selective pressure on VP1 protein of EV71 suggested that immune escape might not be the evolving strategy of EV71, predicting a light future for vaccine development. Nonetheless, long-term antigenic and genetic surveillance is still necessary for further understanding.

Molecular Evidence of Persistent Epidemic and Evolution of Subgenotype B1 Coxsackievirus A16-Associated Hand, Foot, and Mouth Disease in China

ABSTRACT The molecular epidemiology of CVA16 in China between 1999 and 2008 reflects a pattern of endemic cocirculation of clusters B1a and B1b within subgenotype B1 viruses. The annual evolution rate of CVA16 was estimated as approximately 0.91 × 10−2 substitutions per synonymous nucleotide/year and is slightly lower than that of HEV71.

A Sabin 3-Derived Poliovirus Recombinant Contained a Sequence Homologous with Indigenous Human Enterovirus Species C in the Viral Polymerase Coding Region

ABSTRACT Outbreaks of poliomyelitis caused by circulating vaccine-derived polioviruses (cVDPVs) have been reported in areas where indigenous wild polioviruses (PVs) were eliminated by vaccination. Most of these cVDPVs contained unidentified sequences in the nonstructural protein coding region which were considered to be derived from human enterovirus species C (HEV-C) by recombination. In this study, we report isolation of a Sabin 3-derived PV recombinant (Cambodia-02) from an acute flaccid paralysis (AFP) case in Cambodia in 2002. We attempted to identify the putative recombination counterpart of Cambodia-02 by sequence analysis of nonpolio enterovirus isolates from AFP cases in Cambodia from 1999 to 2003. Based on the previously estimated evolution rates of PVs, the recombination event resulting in Cambodia-02 was estimated to have occurred within 6 months after the administration of oral PV vaccine (99.3% nucleotide identity in VP1 region). The 2BC and the 3Dpol coding regions of Cambodia-02 were grouped into the genetic cluster of indigenous coxsackie A virus type 17 (CAV17) (the highest [87.1%] nucleotide identity) and the cluster of indigenous CAV13-CAV18 (the highest [94.9%] nucleotide identity) by the phylogenic analysis of the HEV-C isolates in 2002, respectively. CAV13-CAV18 and CAV17 were the dominant HEV-C serotypes in 2002 but not in 2001 and in 2003. We found a putative recombination between CAV13-CAV18 and CAV17 in the 3CDpro coding region of a CAV17 isolate. These results suggested that a part of the 3Dpol coding region of PV3(Cambodia-02) was derived from a HEV-C strain genetically related to indigenous CAV13-CAV18 strains in 2002 in Cambodia.

Retrospective seroepidemiology indicated that human enterovirus 71 and coxsackievirus A16 circulated wildly in central and southern China before large-scale outbreaks from 2008

BackgroundLarge nationwide outbreaks of hand, foot, and mouth disease (HFMD) occurred in China from 2008; most of the cases were in children under 5 years. This study aims to identify the situation of natural human enterovirus 71 (HEV71) and coxsackievirus A16 (CVA16) infections in children before 2008 in China.ResultsRetrospective seroepidemiologic studies of HEV71 and CVA16 were performed with 900 serum samples collected from children ≤5 years of age in 2005. The samples were collected from 6 different geographical areas (Anhui, Guangdong, Hunan, Xinjiang, Yunnan, and Heilongjiang provinces) in mainland China. Of the 900 samples, 288 were positive for HEV71; the total positive rate was 32.0% and the geometric mean titer (GMT) was 1:8.5. Guangdong (43.7% and 1:10.8), Xinjiang (45.4% and 1:11.1), and Yunnan (43.4% and 1:12.0) provinces had relatively high rates of infection, while Heilongjiang province (8.1% and 1:4.9) had the lowest rate of infection. On the other hand, 390 samples were positive for CVA16; the total positive rate was 43.4% and the GMT was 1:9.5. Anhui (62.2% and 1:16.0) and Hunan (61.1% and 1:23.1) had relatively high rates, while Heilongjiang (8.0% and 1:4.6) had the lowest rate. Although there is a geographical difference in HEV71 and CVA16 infections, low neutralizing antibody positive rate and titer of both viruses were found in all 6 provinces.ConclusionsThis report confirmed that HEV71 and CVA16 had wildly circulated in a couple provinces in China before the large-scale outbreaks from 2008. This finding also suggests that public health measures to control the spread of HEV71 and CVA16 should be devised according to the different regional characteristics.

Emergence and Transmission Pathways of Rapidly Evolving Evolutionary Branch C4a Strains of Human Enterovirus 71 in the Central Plain of China

Background Large-scale outbreaks of hand, foot, and mouth disease (HFMD) occurred repeatedly in the Central Plain of China (Shandong, Anhui, and Henan provinces) from 2007 until now. These epidemics have increased in size and severity each year and are a major public health concern in mainland China. Principal Findings Phylogenetic analysis was performed and a Bayesian Markov chain Monte Carlo tree was constructed based on the complete VP1 sequences of HEV71 isolates. These analyses showed that the HFMD epidemic in the Central Plain of China was caused by at least 5 chains of HEV71 transmission and that the virus continued to circulate and evolve over the winter seasons between outbreaks. Between 1998 and 2010, there were 2 stages of HEV71 circulation in mainland China, with a shift from evolutionary branch C4b to C4a in 2003–2004. The evolution rate of C4a HEV71 was 4.99×10-3 substitutions per site per year, faster than the mean of all HEV71 genotypes. The most recent common ancestor estimates for the Chinese clusters dated to October 1994 and November 1993 for the C4a and C4b evolutionary branches, respectively. Compared with all C4a HEV71 strains, a nucleotide substitution in all C4b HEV71 genome (A to C reversion at nt2503 in the VP1 coding region, which caused amino acid substitution of VP1–10: Gln to His) had reverted. Conclusions The data suggest that C4a HEV71 strains introduced into the Central Plain of China are responsible for the recent outbreaks. The relationships among HEV71 isolates determined from the combined sequence and epidemiological data reveal the underlying seasonal dynamics of HEV71 circulation. At least 5 HEV71 lineages circulated in the Central Plain of China from 2007 to 2009, and the Shandong and Anhui lineages were found to have passed through a genetic bottleneck during the low-transmission winter season.

Complete Genome Analysis of the C4 Subgenotype Strains of Enterovirus 71: Predominant Recombination C4 Viruses Persistently Circulating in China for 14 Years

Genetic recombination is a well-known phenomenon for enteroviruses. To investigate the genetic characterization and the potential recombination of enterovirus 71 (EV71) circulating in China, we determined the 16 complete genome sequences of EV71 isolated from Hand Foot Mouth Disease (HFMD) patients during the large scale outbreak and non-outbreak years since 1998 in China. The full length genome sequences of 16 Chinese EV71 in present study were aligned with 186 genome sequences of EV71 available from GenBank, including 104 China mainland and 82 international sequences, covering the time period of 1970–2011. The oldest strains of each subgenotype of EV71 and prototype strains of HEV-A were included to do the phylogenetic and Simplot analysis. Phylogenetic analysis indicated that all Chinese strains were clustered into C4 subgenotype of EV71, except for HuB/CHN/2009 clustered into A and Xiamen/CHN/2009 clustered into B5 subgenotype. Most of C4 EV71 were clustered into 2 predominant evolutionary branches: C4b and C4a evolutionary brunches. Our comprehensive recombination analysis showed the evidence of genome recombination of subgenotype C4 (including C4a and C4b) sequences between structural genes from genotype C EV71 and non-structural genes from the prototype strains of CAV16, 14 and 4, but the evidence of intratypic recombination between C4 strains and B subgenotype was not enough strong. This intertypic recombination C4 viruses were first seen in 1998 and became the predominant endemic viruses circulating in China mainland for at least 14 years. A shift between C4a and C4b evolutionary brunches of C4 recombination viruses were observed, and C4a viruses have been associated with large scale nationwide HFMD outbreak with higher morbidity and mortality since 2007.

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.

Prevalence of Multiple Enteroviruses Associated with Hand, Foot, and Mouth Disease in Shijiazhuang City, Hebei Province, China: Outbreaks of Coxsackieviruses A10 and B3

Hand, foot, and mouth disease (HFMD) has been one of the most common infectious diseases in Shijiazhuang City, as is the situation in China overall. In the National HFMD surveillance system, the pathogen detection was focused on EV-A71 and CVA16, and therefore, information on the other EVs is very limited. In order to identify the circulating EV serotypes in the HFMD outbreaks in Shijiazhuang City during 2010–2012, 4045 patients presented with HFMD were recruited in the study, and clinical samples were investigated. Typing of EV serotypes was performed using the molecular typing methods, and phylogenetic analyses based on entire VP1 sequences of human enterovirus 71 (EV-A71), coxsackievirus A16 (CVA16), CVA10 and CVB3 was performed. The results revealed that EV-A71 and CVA16 were the 2 most important pathogens but the circulating trends of the 2 viruses showed a shift, the spread of EV-A71 became increasingly weak, whereas the spread of CVA16 became increasingly stronger. CVA10 and CVB3 were the third and fourth most prevalent pathogens, respectively. Co-infection of two viruses at the same time was not found in these samples. Based on entire VP1 region sequences, the phylogenetic analysis revealed that C4a subgenotype EV-A71, B1a and B1b subgenotype CVA16 continued to evolve. The CVA10 strains were assigned to 4 genotypes (A–D), whereas the CVB3 strains were assigned to 5 genotypes (A–E), with clear geographical and temporal-specific distributions. The Shijiazhuang CVA10 sequences belonged to 4 epidemic lineages within genotype C, whereas the Shijiazhuang CVB3 sequences belonged to 2 epidemic lineages within genotype E, which may have the same origins as the strains reported in other part of China. CVA10 and CVB3, 2 pathogens that were previously infrequently detected, were identified as pathogens causing the HFMD outbreaks. This study underscores the need for detailed laboratory-based surveillances of HFMD in mainland China.