Terminal RNA Replication Elements in Human Parechovirus 1

To define structural elements critical for RNA replication in human parechovirus 1 (HPeV1), a replicon with chloramphenicol acetyltransferase as a reporter gene and an infectious virus cDNA clone have been used. It was observed that there are cis-acting signals required for HPeV1 replication located within the 5′-terminal 112 nucleotides of the genome and that these include two terminal stem-loops, SL-A and SL-B, together with a pseudoknot element. Significant disruption of any of these structures impaired both RNA replication and virus growth. In view of the similarity in terminal structures to several picornaviruses, such as cardioviruses and hepatoviruses, the insights generated in this work are of wider significance for understanding picornavirus replication

Integrin α(v)β(6) Is an RGD-Dependent Receptor for Coxsackievirus A9

Coxsackievirus A9 (CAV9), a member of the Enterovirus genus of Picornaviridae, is a common human pathogen and is one of a significant number of viruses containing a functional arginine-glycine-aspartic acid (RGD) motif in one of their capsid proteins. Previous studies identified the RGD-recognizing integrin α(v)β(3) as its cellular receptor. However, integrin α(v)β(6) has been shown to be an efficient receptor for another RGD-containing picornavirus, foot-and-mouth disease virus (FMDV). In view of the similarity in sequence context of the RGD motifs in CAV9 and FMDV, we investigated whether α(v)β(6) can also serve as a receptor for CAV9. We found that CAV9 can bind to purified α(v)β(6) and also to SW480 cells transfected with β(6) cDNA, allowing expression of α(v)β(6) on their surface, but it cannot bind to mock-transfected cells. In addition, a higher yield of CAV9 was obtained in β(6)-expressing cells than in mock-transfected cells. There was no similar enhancement in infection with an RGD-less CAV9 mutant. We also found β(6) on the surface of GMK cells, a cell line which CAV9 infects efficiently by an RGD-dependent mechanism. Significantly, this infection is blocked by an antibody to α(v)β(6), while this antibody did not block the low level of infection by the RGD-less mutant. Thus, integrin α(v)β(6) is an RGD-dependent receptor for CAV9 and may be important in natural CAV9 infections

Molecular Analysis of an Echovirus 3 Strain Isolated from an Individual Concurrently with Appearance of Islet Cell and IA-2 Autoantibodies

Growing evidence has implicated members of the genus Enterovirus of the family Picornaviridae in the etiology of some cases of type 1 diabetes (T1D). To contribute to an understanding of the molecular determinants underlying this association, we determined the complete nucleotide sequence of a strain of echovirus 3 (E3), Human enterovirus B (HEV-B) species, isolated from an individual who soon after virus isolation developed autoantibodies characteristic of T1D. The individual has remained positive for over 6 years for tyrosine phosphatase-related IA-2 protein autoantibodies and islet cell autoantibodies, indicating an ongoing autoimmune process, although he has not yet developed clinical T1D. The sequence obtained adds weight to the observation that recent enterovirus isolates differ significantly from prototype strains and provides further evidence of a role for recombination in enterovirus evolution. In common with most HEV-B species members, the isolate exhibits 2C and VP1 sequences suggested as triggers of autoimmunity through molecular mimicry. However, comparisons with the E3 prototype strain and previously reported diabetogenic and nondiabetogenic HEV-B strains do not reveal clear candidates for sequence features of PicoBank/DM1/E3 that could be associated with autoantibody appearance. This is the first time a virus strain isolated at the time of commencement of beta-cell damage has been analyzed and is an invaluable addition to enterovirus strains isolated previously at the onset of T1D in the search for specific molecular features which could be associated with diabetes induction