Nucleotide sequence of the envelope protein gene of the tick-borne flavivirus, Kumlinge A52

The envelope protein gene of the tick-borne flavivirus, Kumlinge A52, the prototype Finnish strain, has been amplified and sequenced.* The nucleotide and deduced amino acid sequence has been analyzed and compared with the closely related tick-borne encephalitis (TBE) virus, Western subtype, strain Neudoerfl, isolated in Austria. Although these two virus strains were isolated 12 years apart from different hosts and in different countries, the envelope proteins only differed by a single amino acid. It is likely, therefore, that strong selection pressures against antigenic variation exist. The possible reasons for this are discussed.