Serological and molecular findings during SARS-CoV-2 infection: the first case study in Finland, January to February 2020.

The first case of coronavirus disease (COVID-19) in Finland was confirmed on 29 January 2020. No secondary cases were detected. We describe the clinical picture and laboratory findings 3-23 days since the first symptoms. The SARS-CoV-2/Finland/1/2020 virus strain was isolated, the genome showing a single nucleotide substitution to the reference strain from Wuhan. Neutralising antibody response appeared within 9 days along with specific IgM and IgG response, targeting particularly nucleocapsid and spike proteins.

Immunity against vaccine-preventable diseases in Finnish pediatric healthcare workers in 2015.

Healthcare workers (HCWs) pose a risk to themselves and their patients if not protected against vaccine-preventable diseases. Alarmingly, lacking immunity has been reported in several studies. We assessed the immunity against vaccine-preventable diseases in 157 pediatric HCWs in Helsinki Children's Hospital. The HCWs enrolled answered a questionnaire and gave a serum sample. Antibodies were measured with EIA against MMR-diseases, tetanus and diphtheria toxins, Hepatitis B (HBV), Hepatitis A (HAV), varicella zoster and pertussis toxin. Neutralizing antibodies against poliovirus 1, 2 and 3 were measured. All of the HCWs had antibodies against tetanus and 89.8% against diphtheria. All had measurable levels of polio antibodies to all three polioviruses. 41% had suboptimal levels of antibodies against at least one of the antigens tested: MMR-viruses, diphtheria, HBV or polio. Measles, mumps and rubella antibodies were detectable in 81.5%, 89.2% and 93%, respectively. Only one HCW had no varicella-antibodies. Hepatitis B surface antibodies (HBsAb) were detected in 89.8% of the nurses. 67.5% had HAV-antibodies. A poor correlation between detected antibody levels and reported vaccination history was noticed, indicating a need for a universal record system for registering the vaccines given to each individual.

Molecular evolution and epidemiology of echovirus 6 in Finland.

Echovirus 6 (E-6) (family Picornaviridae, genus Enterovirus) is one of the most commonly detected enteroviruses worldwide. The aim of this study was to determine molecular evolutionary and epidemiologic patterns of E-6. A complete genome of one E-6 strain and the partial VP1 coding regions of 169 strains were sequenced and analyzed along with sequences retrieved from the GenBank. The complete genome sequence analysis suggested complex recombination history for the Finnish E-6 strain. In VP1 region, the phylogenetic analysis suggested three major clusters that were further divided to several subclusters. The evolution of VP1 coding region was dominated by negative selection suggesting that the phylogeny of E-6 VP1 gene is predominantly a result of synonymous substitutions (i.e. neutral genetic drift). The partial VP1 sequence analysis suggested wide geographical distribution for some E-6 lineages. In Finland, multiple different E-6 lineages have circulated at the same time.

Molecular characterization of human rhinovirus field strains isolated during surveillance of enteroviruses.

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.

Molecular epidemiology and dual serotype specificity detection of echovirus 11 strains in Finland.

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.

Enterovirus 94, a proposed new serotype in human enterovirus species D.

The genus Enterovirus (family Picornaviridae) contains five species with strains isolated from humans: Human enterovirus A (HEV-A), HEV-B, HEV-C, HEV-D and Poliovirus. In this study, a proposed new serotype of HEV-D was characterized. Four virus strains were isolated from sewage in Egypt and one strain from acute flaccid paralysis cases in the Democratic Republic of the Congo. The complete genome of one environmental isolate, the complete coding sequence of one clinical isolate and complete VP1 regions from the other isolates were sequenced. These isolates had 66.6-69.4% nucleotide similarity and 74.7-76.6% amino acid sequence similarity in the VP1 region with the closest enterovirus serotype, enterovirus 70 (EV70), suggesting that the isolates form a new enterovirus type, tentatively designated enterovirus 94 (EV94). Phylogenetic analyses including sequences of the 5' UTR, VP1 and 3D regions demonstrated that EV94 isolates formed a monophyletic group within the species HEV-D. No evidence of recombination was found between EV94 and the other HEV-D serotypes, EV68 and EV70. Further biological characterization showed that EV94 was acid stable and had a wide cell tropism in vitro. Attempts to prevent replication with protective antibodies to known enterovirus receptors (poliovirus receptor, vitronectin alphavbeta3 receptor and decay accelerating factor) were not successful. Seroprevalence studies in the Finnish population revealed a high prevalence of this virus over the past two decades.

Phylogenetic analysis of human rhinovirus capsid protein VP1 and 2A protease coding sequences confirms shared genus-like relationships with human enteroviruses.

Phylogenetic analysis of the capsid protein VP1 coding sequences of all 101 human rhinovirus (HRV) prototype strains revealed two major genetic clusters, similar to that of the previously reported VP4/VP2 coding sequences, representing the established two species, Human rhinovirus A (HRV-A) and Human rhinovirus B (HRV-B). Pairwise nucleotide identities varied from 61 to 98 % within and from 46 to 55 % between the two HRV species. Interserotypic sequence identities in both HRV species were more variable than those within any Human enterovirus (HEV) species in the same family. This means that unequivocal serotype identification by VP1 sequence analysis used for HEV strains may not always be possible for HRV isolates. On the other hand, a comprehensive insight into the relationships between VP1 and partial 2A sequences of HRV and HEV revealed a genus-like situation. Distribution of pairwise nucleotide identity values between these genera varied from 41 to 54 % in the VP1 coding region, similar to those between heterologous members of the two HRV species. Alignment of the deduced amino acid sequences revealed more fully conserved amino acid residues between HRV-B and polioviruses than between the two HRV species. In phylogenetic trees, where all HRVs and representatives from all HEV species were included, the two HRV species did not cluster together but behaved like members of the same genus as the HEVs. In conclusion, from a phylogenetic point of view, there are no good reasons to keep these two human picornavirus genera taxonomically separated.

Presence of specific viruses in the middle ear fluids and respiratory secretions of young children with acute otitis media.

The purpose of the study was to investigate the presence of different viruses in middle ear fluids and nasopharyngeal aspirates in young children with acute otitis media. Two cohorts of children (N = 329 and 611) were followed from 2 to 24 months of age in Finland in two prospective studies (Finnish Otitis Media Cohort Study and Finnish Otitis Media Vaccine Trial). During the study period, nasopharyngeal and middle ear fluid specimens for each acute otitis media event were examined for eight (Cohort Study) or ten (Vaccine Trial) common respiratory viruses; adenoviruses, influenza viruses A and B, parainfluenza viruses 1, 2, and 3, respiratory syncytial virus (RSV), enteroviruses, parechoviruses, and rhinoviruses. Picornaviruses (rhinoviruses, enteroviruses, and parechoviruses) were determined by reverse transcription PCR while antigen detection was used for the other viruses. A virus was present in either nasopharyngeal or middle ear specimen in 54% of events in the first cohort and in 67% of events in the second. Rhinoviruses formed the most common virus group detected (41-32%), followed by enteroviruses (25%, sought in the second cohort only) and respiratory syncytial virus (RSV) (10%). All the other viruses represented jointly 8-10% of the events. In conclusion, using the methods described in this study, a specific virus infection was diagnosed in two thirds of all acute otitis media events in young children. Picornavirus RNA was detected in association with more than a half of all acute otitis media events. The use of PCR-based methods for the other respiratory viruses might have increased further the overall virus detection rate in acute otitis media.