Anja Paananen

Co-circulation of coxsackieviruses A6 and A10 in hand, foot and mouth disease outbreak in Finland

BACKGROUND A nationwide outbreak of hand, foot and mouth disease (HFMD) occurred in Finland in autumn 2008. The outbreak was untypical since a considerable number of clinically diagnosed patients were adults. Furthermore, many of the patients suffered from onychomadesis several weeks after the acute phase of HFMD. OBJECTIVES Detection, identification and phylogenetic analysis of human enteroviruses (HEV) that caused the outbreak. STUDY DESIGN A total of 420 clinical specimens were obtained from 317 HFMD cases all over the country. The presence of HEV in the specimens was analysed by virus isolation and/or direct real-time RT-PCR; selected HEV strains were further typed by molecular methods. The genetic similarities of HEV strains were assessed by phylogenetic analyses on partial VP1 sequences. RESULTS HEV were detected in 212 HFMD cases, including both children and adults, throughout Finland. Two HEV types, coxsackieviruses A6 (CV-A6) and A10 (CV-A10), were identified as the causative agents of the outbreak. One genetic variant of CV-A6 predominated, but, additionally, three other genetically distinct CV-A6 strains were found. All CV-A10 strains segregated into one genetic cluster distinct from previously reported CV-A10 sequences. CONCLUSIONS The Finnish 2008 HFMD outbreak was caused by two infrequently detected, co-circulating, coxsackie A viruses. Our data suggest endemic circulation of both CV-A types in Northern Europe and that the outbreak was due to the emergence of new genetic variants of these viruses.

Eight Years of Experience with Molecular Identification of Human Enteroviruses

ABSTRACT We have successfully typed 1,121 human enterovirus (HEV) isolates during the last 8 years by adapting partial VP1 sequencing to routine identification of HEV isolated from diverse clinical and environmental specimens. The isolates include 48 of the 59 traditional nonpoliovirus HEV serotypes and members of 8 newly discovered types, which would have remained untypeable by neutralization using the conventional cross-sectional pools of antisera.

An enterovirus strain isolated from diabetic child belongs to a genetic subcluster of echovirus 11, but is also neutralised with monotypic antisera to coxsackievirus A9

An enterovirus strain (designated D207) isolated from a Slovakian diabetic child and originally serotyped as coxsackievirus A9 (CAV-9) was found to cause rapid cytolysis coinciding with severe functional damage of the surviving cells in primary cultures of human pancreatic islets. This finding prompted us to clone the isolate for full-length genome sequencing and molecular characterization as the prototype strain of CAV-9 is known to cause only minimal damage to insulin-producing beta-cells. Based on capsid-coding sequence comparisons, the isolate turned out to be echovirus 11 (E-11). Phylogenetic analyses demonstrated that E-11/D207 was closely related to a specific subgroup B of E-11 strains known to cause uveitis. To study further antigenic properties of isolate E-11/D207 and uveitis-causing E-11 strains, neutralization experiments were carried out with CAV-9- and E-11-specific antisera. Unlike the prototype strains, the isolate E-11/D207 and uveitis-causing E-11 strains were well neutralized with both CAV-9- and E-11-specific antisera. Attempts to identify recombination of the capsid coding sequences as a reason for double-reactivity using the Simplot analysis failed to reveal major transferred motifs. However, peptide scanning technique was able to identify antigenic regions of capsid proteins of E-11/D207 as well as regions cross-reacting with an antiserum raised to CAV-9. Thus, double specificity of E-11/D207 seems to be a real characteristic shared by the phylogenetically closely related virus strains in the genetic subgroup B of E-11.

Characteristics of an Environmentally Monitored Prolonged Type 2 Vaccine Derived Poliovirus Shedding Episode that Stopped without Intervention

Vaccine derived poliovirus (VDPV) type 2 strains strongly divergent from the corresponding vaccine strain, Sabin 2, were repeatedly isolated from sewage in Slovakia over a period of 22 months in 2003–2005. Cell cultures of stool specimens from known immune deficient patients and from an identified putative source population of 500 people failed to identify the potential excretor(s) of the virus. The occurrence of VDPV in sewage stopped without any intervention. No paralytic cases were reported in Slovakia during the episode. According to a GenBank search and similarity plotting-analysis, the closest known relative of the first isolate PV2/03/SVK/E783 through all main sections of the genome was the type 2 poliovirus Sabin strain, with nucleotide identities in 5′UTR, P1, P2, P3, and 3′UTR parts of the genome of 88.6, 85.9, 87.3, 88.5, and 94.0 percent, respectively. Phenotypic properties of selected Slovakian aVDPV strains resembled those of VDPV strains isolated from immune deficient individuals with prolonged PV infection (iVDPV), including antigenic changes and moderate neurovirulence in the transgenic mouse model. One hundred and two unique VP1 coding sequences were determined from VDPV strains isolated from 34 sewage specimens. Nucleotide differences from Sabin 2 in the VP1 coding region ranged from 12.5 to 15.6 percent, and reached a maximum of 9.6 percent between the VDPV strains under study. Most of the nucleotide substitutions were synonymous but as many as 93 amino acid positions out of 301 in VP1 showed substitutions. We conclude that (1) individuals with prolonged poliovirus infection are not as rare as suggested by the studies on immune deficient patients known to the health care systems and (2) genetic divergence of VDPV strains may remain extensive during years long replication in humans.

Detection of Imported Wild Polioviruses and of Vaccine-Derived Polioviruses by Environmental Surveillance in Egypt

ABSTRACT Systematic environmental surveillance for poliovirus circulation has been conducted in Egypt since 2000. The surveillance has revealed three independent importations of wild-type poliovirus. In addition, several vaccine-derived polioviruses have been detected in various locations in Egypt. In addition to acute flaccid paralysis (AFP) surveillance, environmental surveillance can be used to monitor the wild poliovirus and vaccine-derived poliovirus circulation in populations in support of polio eradication initiatives.

A single amino acid substitution in viral VP1 protein alters the lytic potential of clone-derived variants of echovirus 9 DM strain in human pancreatic islets.

In vitro studies with primary human pancreatic islets suggest that several enterovirus serotypes are able to infect and replicate in beta cells. Some enterovirus strains are highly cytolytic in vitro whereas others show virus replication with no apparent islet destruction. The capability to induce islet destruction is determined only partially by the virus serotype, since strain specific differences have been detected within some serotypes including echovirus 9 (E‐9). In this study, the viral genetic factors determining the outcome of islet infection (i.e., destructive vs. benign) were investigated by constructing parallel infectious clones of lytic E‐9‐DM strain that was isolated from a small child at the clinical onset of type 1 diabetes. The capabilities of these clone‐derived viruses to induce islet destruction were monitored and the lytic potential of clones was modified by site‐directed mutagenesis. The lytic capabilities of these clone‐derived viruses in human pancreatic islets were modified by a single amino acid substitution (T81A) in the capsid protein VP1. The data presented outline the importance of amino acid point mutations in the pathogenetic process leading to islet necrosis. However, although the amino acid substitution (T81A) modifies the lytic capabilities of E‐9‐DM strain‐derived microvariant strains, it is likely that additional viral genetic determinants of pancreatic islet pathogenicity exist in other E‐9 strains. J. Med. Virol. 85:1267–1273, 2013.

Isolation of saffold virus type 2 in green monkey kidney cells.

Saffold viruses (SAFV) have been discovered recently and they are classified into Theilovirus species in genus Cardiovirus in the Picornaviridae family. SAFV, especially those belonging to the genotype 2, have been difficult to propagate in laboratory cell lines. This study describes the successful isolation of an efficiently growing SAFV‐2 strain directly from a stool specimen by standard virological methods. The availability of SAFV isolates that can be propagated to high titers is crucial to the future studies on pathogenesis and epidemiology of these novel human viruses. J. Med. Virol. 84:1497–1500, 2012.