Rotavirus serotypes and electropherotypes in Finland from 1986 to 1990

Abstract

Four epidemic seasons of rotaviruses were studied in Helsinki during 1986-1990. This is the first Scandinavian study, where both electropherotypes and serotypes are determined. Out of 5316 fecal specimens 769 (14.5%) rotavirus positive samples were detected by electron microscopy. Of these, 645 isolates (83.9%) gave a clear RNA pattern in gel electrophoresis and they clustered into 87 electropherotypes. An illustrative number of isolates representing each electropherotype (= E-type) was serotyped using VP7 protein-specific monoclonal antibodies for serotypes G1-G4 and without exceptions, within one E-type only a single serotype specificity was found. After establishment of the serotype of each E-type, the distribution of serotypes was scored as 61.2%, 2.0%, 0.5% and 29.8% for G1-G4, respectively; 6.5% remained untypable. Two seasons had one predominant E-type (Season 1, 1986-87, and Season 3, 1988-89, 84.2% and 80.6% of rotavirus positive samples, respectively). Both were followed by a season with no predominant E-type, but several minor E-types. Altogether, 5 short E-types (13/645 samples) with serotype G2 specificity were found, most of them occurring in Season 2. Only 2 E-types (3 samples) belonged to serotype G3. Group C rotavirus was found in 8 specimens. In this study a shift in serotypes, from G1 to G4, was observed in Finland in 1988/89; a similar shift was reported in many European countries at that time.

Diversity of Group A Human Rotavirus Types Circulating over a 4-Year Period in Madrid, Spain

“…In this 4-year study, the G1 type was the most prevalent (53%), followed by the G4 type (24%). These results emphasize the high frequency of the G1 and G4 types circulating in European countries (3,9,26,29,33,35,36). Although the G1 type was the most prevalent rotavirus type in Madrid during the sampling period, we have detected an important genotypic shift from type G4 to G1 over the 4 years of study.…”

Heterogeneity and Temporal Dynamics of Evolution of G1 Human Rotaviruses in a Settled Population

“…While between 1985 and 2004, G2P [4], G4P [8], and G9P [8] strains varied in their distribution or completely disappeared for short or long periods of time, G1 strains have been continuously circulating in the infant population of Palermo, a pattern that has been described in various other geographical settings as well (6,9,11,25,35,46,58,59). However, unlike the G2P [4] and G4P [8] Italian rotavirus strains, a highly heterogeneous population of G1 strains has been circulating in Italy over the whole study period.…”

Frequent Reassortments May Explain the Genetic Heterogeneity of Rotaviruses: Analysis of Finnish Rotavirus Strains

“…To define the most predominant rotavirus strains, approximately 150 to 200 virus isolates per epidemic season from the 1981 to the 1986 season were run in gels, and all samples for the seasons from 1986 to 1997 were electrophoresed. The e-types during the years 1987 to 1990 had been determined previously (35). The most common e-type was considered predominant if its prevalence was higher than 30% during the season.…”

“…RNA extraction, gel electrophoresis, and silver staining were performed as previously described (35). Briefly, the nucleic acid from a rotavirus-positive stool suspension was extracted by treatment with phenol and chloroform-isoamyl alcohol, followed by ethanol-acetate precipitation.…”

“…In gels the electropherotypes (e-types), or RNA profiles, expressing a high number of RNA segment migration differences among rotavirus isolates, could be distinguished. Changes in the migration of the 11 RNA segments do not reveal the nature of mutational events (7), but when the place and time scale are limited, an e-type seems to correspond to a virus strain (3,8,35). It is typical for a vast diversity of rotavirus strains with different P/G combinations to be cocirculating in a rotavirus epidemic season (3,20).…”