Genomic characterization of an enterovirus 97 strain isolated in Shandong, China

Molecular Epidemiological, Serological, and Pathogenic Analysis of EV-B75 Associated With Acute Flaccid Paralysis Cases in Tibet, China

Enterovirus B75 (EV-B75) is a newly identified serotype of the enterovirus B species. To date, only 112 cases related to EV-B75 have been reported worldwide, and research on EV-B75 is still limited with only two full-length genome sequences available in GenBank. The present study reported seven EV-B75 sequences from a child with acute flaccid paralysis and six asymptomatic close contacts in Shigatse, Tibet. Phylogenetic analysis revealed that the Tibetan strain was possibly imported from neighboring India. Seroepidemiological analyses indicated that EV-B75 has not yet caused a large-scale epidemic in Tibet. Similarity plots and boot scanning analyses revealed frequent intertypic recombination in the non-structural region of all seven Tibet EV-B75 strains. All seven Tibetan strains were temperature-sensitive, suggesting their poor transmissibility in the environment. Overall, though the seven Tibetan strains did not cause large-scale infection, prevention and control of the novel enterovirus cannot be underestimated.

Isolation and Characterization of a Highly Mutated Chinese Isolate of Enterovirus B84 from a Patient with Acute Flaccid Paralysis

Enterovirus B84 (EV-B84) is a newly identified serotype within the species Enterovirus B (EV-B). To date, only ten nucleotide sequences of EV-B84 are published and only one full-length genome sequence (the prototype strain) is available in the GenBank database. Here, a highly mutated EV-B84 (strain AFP452/GD/CHN/2004) was recovered from a patient with acute flaccid paralysis in the Guangdong province of China in 2004 making this the first report of EV-B84 in China. Sequence comparison and phylogenetic dendrogram analysis revealed high variation from the global EV-B84 strains (African and Indian strains) and frequent intertypic recombination in the non-structural protein region, suggesting high genetic diversity in EV-B84. The Chinese EV-B84 strain, apparently evolving independently of the other ten strains, strongly suggests that the EV-B84 strain has been circulating for many years. However, the extremely low isolation rate suggests that it is not a prevalent EV serotype in China or worldwide. This study provides valuable information about the molecular epidemiology of EV-B84 in China, and will be helpful in future studies to understand the association of EV-B84 with neurological disorders; it also helps expand the number of whole virus genome sequences of EV-B84 in the GenBank database.

Recombination among human non-polio enteroviruses: implications for epidemiology and evolution

Human enteroviruses (EV) belong to the Picornaviridae family and are among the most common viruses infecting humans. They consist of up to 100 immunologically and genetically distinct types: polioviruses, coxsackieviruses A and B, echoviruses, and the more recently characterized 43 EV types. Frequent recombinations and mutations in enteroviruses have been recognized as the main mechanisms for the observed high rate of evolution, thus enabling them to rapidly respond and adapt to new environmental challenges. The first signs of genetic exchanges between enteroviruses came from polioviruses many years ago, and since then recombination has been recognized, along with mutations, as the main cause for reversion of vaccine strains to neurovirulence. More recently, non-polio enteroviruses became the focus of many studies, where recombination was recognized as a frequent event and was correlated with the appearance of new enterovirus lineages and types. The accumulation of multiple inter- and intra-typic recombination events could also explain the series of successive emergences and disappearances of specific enterovirus types that could in turn explain the epidemic profile of circulation of several types. This review focuses on recombination among human non-polio enteroviruses from all four species (EV-A, EV-B, EV-C, and EV-D) and discusses the recombination effects on enterovirus epidemiology and evolution.

Complete genome analysis of human enterovirus B73 isolated from an acute flaccid paralysis patient in Shandong, China

Human enterovirus B73 (EV-B73) is a member of species Enterovirus B. To date, only one complete genome sequence of prototype strain CA55-1988 from California has been available. In this study, the complete genome analysis of an EV-B73 strain 088/SD/CHN/04 isolated from an acute flaccid paralysis case in Shandong Province, China in 2004 is conducted. It had 75.6 and 79.3 % nucleotide similarity with prototype strain CA55-1988 in the VP1 coding region and the complete genome, respectively. It had great VP1 nucleotide divergence (16.7-24.4 %) with EV-B73 strains from other parts of the world. Similarity plot and bootscanning analyses provided evidence of recombination with other EV-B viruses.

Isolation and genomic characterization of three enterovirus 90 strains in Shandong, China

Enterovirus 90 (EV90) is a newly identified serotype of the species Human enterovirus A, and few nucleotide sequences of EV90 are available. In this study, three EV90 strains were isolated from acute flaccid paralysis (AFP) cases in Shandong Province, China, in 2001 and 2003. Sequence analysis revealed 96.7-98.0 % VP1 nucleotide identity among themselves and 77.7-92.3 % to other EV90 strains. Complete genome analysis provided evidence of recombination in the non-capsid coding region of strain 01421. This is the first report of EV90 in China, and the low isolation rate suggests that it has not been a prevalent serotype in China.

The complete genome sequence of an enterovirus 76 isolate in China reveals a recombination event

Enterovirus 76 (EV76) is a new member of species Human Enterovirus A (HEV-A). So far, the only complete genome sequence of the prototype strain from France has been available. In this study, we determined the complete nucleotide sequence of strain 04360, isolated from an acute flaccid paralysis patient in Shandong province, China in 2004. Sequence analysis revealed 80.7-94.7% VP1 nucleotide identity to other EV76 strains and provided evidence of recombination with other types of HEV-A in the P2 and P3 coding regions.

The complete genome analysis of two enterovirus 96 strains isolated in China in 2005 and 2009

Enterovirus 96 (EV96) is a new member of species Human Enterovirus C (HEV-C). In this report, genomic characterization of two EV96 strains isolated from acute flaccid paralysis surveillance in Shandong province of China in 2005 and 2009 is described. The two strains, designated 05517 and 09228C1, had 82.7% genomic similarity with each other and 75.1-84.2% with other three strains available from GenBank in complete genome sequences. In VP1 coding region, they had 77.6-86.6% nucleotide similarity with other EV96 strains. Interestingly, deletions of 3 nucleotides in the VP3 coding region of strain 09228C1, and of 3 nucleotides in the 3A region of both Shandong strains were observed. Simplot and bootscanning analysis on HEV-C genome sequences were performed, and evidence of recombination in P3 region for Shandong EV96 strains was found. In conclusion, these strains had distant genetic relationship with each other and with other EV96 strains.

Evolution of newly described enteroviruses

Several new enterovirus serotypes and a new human rhinovirus species have been characterized in the Enterovirus genus recently, raising a question about the origin of the new viruses. In this article we attempt to outline the general patterns of enterovirus evolution, ultimately leading to the emergence of new serotypes or species. Different evolutionary and epidemiological patterns can be deduced between different enterovirus species, between entero- and rhino-viruses and between different serotypes within a species. This article presents a hypothesis that the divergent evolution leading to a new serotype is likely to involve adaptation to a new ecological niche either within a single host species or due to interspecies transmission. By contrast, evolution within a serotype appears to occur primarily by genetic drift.