Evolution of Newly Described Enteroviruses

Abstract

Enteroviruses (EVs) are small nonenveloped RNA viruses. The genus Enterovirus makes up the Picornaviridae family together with the genera Aphthovirus, Avihepatovirus, Cardiovirus, Erbovirus, Hepatovirus, Kobuvirus, Parechovirus, Sapelovirus, Senecavirus, Teschovirus and Tremovirus. Picornaviruses are classified in the order Picornavirales. The Enterovirus genus currently consists of ten species [301], which are further divided into multiple serotypes. An EV species is defined as a polythetic class of phylogenetically related serotypes or strains that share a limited range of natural hosts and host cell receptors, a significant degree of compatibility in proteolytic processing, replication, encapsidation and genetic recombination, greater than 70% amino acid identity in P1, 2C and 3CD proteins (for all EV genome map see Figure 1A and below) and have a genome (G+C) base composition that varies by no more than 2.5% [1]. Seven of the species; human EV (HEV)-A, HEV-B, HEV-C, HEV-D, human rhinovirus A (HRV-A), HRV-B and HRV-C, are known to infect humans ( Figure 1B). The other species of the genus infect monkeys (Simian EV-A and an as yet unclassified novel species consisting of types SV-6, EV-103 and EV-108 isolated from captive simians [2,3]), bovines (bovine EV) and pigs (porcine EV-B).The EV genome is a single-stranded positivesense RNA molecule of approximately 7500 nucleotides, consisting of a single open reading frame flanked by 5´ and 3´ noncoding regions (NCRs) [4]. The 5´ NCR contains two functional domains; a cloverleaf, which is a cis-acting element in viral replication [5,6] and an internal ribosome-binding site, which is essential for translation initiation [7][8][9]. The 3´ NCR forms highly conserved secondary and tertiary structures that are important in replication initiation [10][11][12][13]. The open reading frame is translated into a single, large polypeptide, which is subsequently cleaved by viral proteases (reviewed in [14]). The polypeptide is divided into three domains, P1-3, consisting of three to four proteins each. The P1 region contains viral capsid proteins VP1-4, whilst P2 and P3 contain the nonstructural proteins 2A-C and 3A-D, respectively ( Figure 1A).Several new EV serotypes and a new HRV species have been characterized in the Enterovirus genus recently. In this article we will focus on the evolution and emergence of new EVs. By definition a new EV type means a previously unknown capsid type, since recombination at the 5´NCR and nonstructural protein coding region appears to be a prominent feature for both new and previously known EV serotypes (see below, [15][16][17][18][19]). In this article we use the term new or newly described virus for those HEV and HRV types that have been characterized by molecular methods (sequence comparison) rather than by antigenical typing methods ('classic' HEV and HRV serotypes). Since at least most of the recently characterized new EVs are not newly arisen but rather newly detected (see below), the question about the origin of the new EV types can ...

Genetic and phenotypic characterization of recently discovered enterovirus D type 111

“…First, the hypothesis of the animal origin of EV-D111 is consistent with the fact that another EV-D, EV-D120, was also detected in wild NHP samples from Central Africa and has never been detected in human samples [8]. It is also consistent with the proposed zoonotic origin of EV-D70, which seems to have emerged among humans in Africa in the 1960s [47, 48]. The recent emergence of EV-D70 in humans is supported by two main arguments: i- previous seroepidemiologic studies have detected EV-D70-neutralizing antibodies in sera from cattle, sheep, swine, dogs and chicken collected in Ghana, Senegal and Japan, of which some had been collected prior to the emergence of acute haemorrhagic conjunctivitis outbreaks in humans [49]; ii- according to phylogenetic studies, all known EV-D70 strains seem to derive from a recent common ancestor [50].…”

A systematic review of evidence that enteroviruses may be zoonotic

“…The EV103-POo-1 amino acid sequences also shared 93 and 96% identity with the SV6 on the P2 and P3 regions. RT-PCR and complete genome sequencing Smura et al 34 Finland 2011 A review of enterovirus species evolution includes a description of possible zoonotic origin of EV-70. Review article Harvala et al 23 Cameroon 2011 Enteroviruses infecting wild chimpanzees were characterized and found to be related to human strains detected in patients in Central Africa, including LM1677 (clustered closely with EV79 in VP1 and VP4/VP2 regions) and KK2640 (grouped closely with the EV70 in the VP1 region and with the EV94 in the 5′UTR and 3Dpol).…”

“…It is well documented that SVDV originated in humans as human coxsackie virus B5, which transferred to pigs between 1945 and 1965 34 , 35 . Through recombination and phylogenetic analysis, Bruhn et al recently suggested that SVDV may have originated from a single recombinant event 36 .…”

The Evolution of Vp1 Gene in Enterovirus C Species Sub-Group That Contains Types CVA-21, CVA-24, EV-C95, EV-C96 and EV-C99

“…Likewise, although the implementation of molecular methods for genetic enterovirus typing has led to the discovery of a large number of novel enterovirus types (reviewed in [6]), much less is known about evolutionary processes behind the formation of the enterovirus types.…”