J Gen Virol. Sep 2012; 93(Pt 9): 1952–1958.
Worldwide emergence of multiple clades of enterovirus 68
Human enterovirus 68 (EV-D68) is a historically rarely reported virus linked with respiratory disease. In the past 3 years, a large increase in respiratory disease associated with EV-D68 has been reported, with documented outbreaks in North America, Europe and Asia. In several outbreaks, genetic differences were identified among the circulating strains, indicating the presence of multiple clades. In this report, we analyse archived and novel EV-D68 strains from Africa and the USA, obtained from patients with respiratory illness. Phylogenetic analysis of all EV-D68 sequences indicates that, over the past two decades, multiple clades of the virus have emerged and spread rapidly worldwide. All clades appear to be currently circulating and contributing to respiratory disease.
Enteroviruses (family Picornaviridae, genus Enterovirus) are non-enveloped, positive-sense ssRNA viruses. Enteroviruses can cause a wide range of clinical symptoms, ranging from mild febrile illness to fatal meningitis and encephalitis and are among the most common human pathogens. A typical enterovirus genome consists of an RNA strand of approximately 7500 nt and contains a single ORF encoding a polyprotein that is processed post-translationally to yield individual viral proteins. The polyprotein ORF is flanked by a UTR at each end, with the 5′ UTR containing the highly conserved internal ribosome entry site (IRES) (Racaniello, 2001). The VP1 gene, which encodes one of four capsid proteins, has traditionally been used to distinguish between enterovirus serotypes and, based on molecular and biological characteristics, four human enterovirus (HEV) species are currently recognized, designated HEV-A, -B, -C and -D (Oberste et al., 1999a, b).