ROTAVIRUS SEROTYPES AND ELECTROPHEROTYPES IN FINLAND FROM 1986 TO 1990

Four epidemic seasons of rotaviruses were studied in Helsinki during 1 986-1990. This is the first Scandinavian study, where both electropher otypes 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 elect rophoresis and they clustered into 87 electropherotypes. An illustrati ve number of isolates representing each electropherotype (= E-type) wa s serotyped using VP7 protein-specific monoclonal antibodies for serot ypes G1-G4 and without exceptions, within one E-type only a single ser otype specificity was found. After establishment of the serotype of ea ch 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 sea sons had one predominant E-type (Season 1, 1986-87, and Season 3, 1988 -89, 84.2% and 80.6% of rotavirus positive samples, respectively). Bot h were followed by a season with no predominant E-type, but several mi nor E-types. Altogether, 5 short E-types (13/645 samples) with serotyp e 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 f ound 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.