ABSTRACT
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.
Subject(s)
Capsid Proteins/genetics , Genetic Variation , Poliovirus/genetics , Sewage/virology , Amino Acid Sequence , Amino Acid Substitution , Animals , Antibodies, Viral/blood , Capsid Proteins/chemistry , Child , Environmental Microbiology , Humans , Mice , Mice, Transgenic , Models, Molecular , Molecular Sequence Data , Phylogeny , Poliovirus/classification , Poliovirus/immunology , Poliovirus Vaccine, Oral/immunology , Protein Multimerization , Seasons , Sequence Homology, Amino Acid , Slovakia , VaccinationABSTRACT
Echovirus 11 (E-11) has been one of the most frequently discovered human enterovirus (HEV) in Finland during the past few years. We have studied molecular epidemiological patterns of E-11 from 1993 to 2007 exploiting the 257-nucleotide region in the 5'-part of the VP1 used for genetic typing of HEV. Designated genogroup D strains had a striking prevalence among the Finnish strains, a finding in accordance with the recent data from other geographical regions. The subgroup D4, harboring the oldest strains, had become extinct in the beginning of the millennium and D5 strains had taken over. Similarly, a new subgroup of D5 had started to diverge from the main D5 in 2006. However, in addition to endemic D strains, few single strains clustered also to genogroups A and C suggesting importation from more distant locations. The relatively large amino acid sequence variability between and within the genogroups favored the idea of antigenic differences. Neutralization assays confirmed that antigenic differences existed, although all studied E-11 strains were neutralized with antisera against the prototype strain Gregory. Five of the six studied strains belonging to genogroup D were, unexpectedly, also neutralized with antisera against coxsackievirus A9 Griggs.
Subject(s)
Antigens, Viral/immunology , Echovirus Infections/virology , Enterovirus B, Human/classification , Enterovirus B, Human/genetics , Animals , Antibodies, Viral/blood , Antigenic Variation , Antigens, Viral/genetics , Cell Line , Cell Line, Tumor , Echovirus Infections/genetics , Echovirus Infections/immunology , Enterovirus B, Human/isolation & purification , Finland/epidemiology , Humans , Molecular Epidemiology , Molecular Sequence Data , Neutralization Tests , Phylogeny , Serotyping , Sewage/virologyABSTRACT
Human enteroviruses are currently grouped into five species Human enterovirus A (HEV-A), HEV-B, HEV-C, HEV-D and Poliovirus. During surveillance for enteroviruses serologically non-typable enterovirus strains were found from acute flaccid paralysis patients and healthy individuals. In this study, we report isolates of recently described enterovirus types EV76 and EV90 of HEV-A species and characterize two new enterovirus type candidates, EV96 and EV97, to species HEV-C and HEV-B, respectively. Analysis of partial 3D regions of EV96 strains revealed sequence divergence consistent with several recombination events between EV96, other HEV-C viruses and polioviruses. Phylogenetic analysis of all available 5'-untranslated region sequences of human entero- and rhinovirus prototype strains and 10 simian enterovirus strains suggested interspecies recombination involving this region.
