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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.

Human rhinoviruses (HRVs), which are the most frequent causative agents of acute upper respiratory tract infections, are abundant worldwide. We have identified HRV strains in environmental specimens collected in Finland, Latvia and Slovakia during the surveillance of polio- and other enteroviruses. These acid-sensitive HRV strains were isolated under conditions optimized for growth of most of the enteroviruses, i.e. in stationary human rhabdomyosarcoma cells incubated at 36 degrees C. Phylogenetic analysis of the sequences derived from the partial 5' non-coding region and the capsid region coding for proteins VP4/VP2 and VP1 showed that the HRV field strains clustered together with prototype strains of the HRV minor receptor group. Partial sequences of the 3D polymerase coding region generally followed this pattern, with the exception of a set of three HRV field strains that formed a subcluster not close to any of the established HRV-A types, suggesting that recombination may have occurred during evolution of these HRV strains. Phylogenetic analysis of the VP4/VP2 capsid protein coding region showed that the 'environmental' HRV field strains were practically identical to HRV strains recently sequenced by others in Australia, the United States and Japan. Analysis of amino acids corresponding to the intercellular adhesion molecule-1 receptor footprint in major receptor group HRVs and also in the low-density lipoprotein receptor footprint of minor receptor group HRVs showed conservation of the 'minor receptor group-like' amino acids, indicating that the field strains may have maintained their minor receptor group specificity.