Genetic typing of classical swine fever virus isolates from Germany

During the last decade several outbreaks of classical swine fever (CSF) occ urred in Germany in domestic pigs and in wild boar, respectively. Two major epidemics which also affected other EU Member States were recorded. To sup port epidemiological investigations genetic typing was applied and virus is olates originating from different outbreaks in Germany were assigned to gro ups and virus types. Two genomic regions were selected for the phylogenetic analysis, namely 150 nucleotides from the 5' nontranslated region (5'-NTR) and 190 nucleotides from the E2 glycoprotein gene. All German CSF virus is olates of the nineties (Group 2) were distinct from former reference strain s (Group 1). Within Group 2 both genomic regions allowed to distinguish thr ee subgroups, namely 2.1, 2.2 and 2.3. Within subgroup 2.3 five virus types could be discriminated using the 5'-NTR sequences. These are 2.3* Uelzen a nd 2.3* Spreda, mainly with isolates from Lower Saxony, as well as 2.3* Ros tock, 2.3* Gustrow and 2.3* Spante, mainly with isolates from Eastern Germa ny. Analysis of the E2 gene fragment allowed a better discrimination betwee n single isolates, but only two virus types could be defined: 2.3* MV/BB, c omprising the isolates from Eastern Germany, and 2.3* NI, with the isolates from Lower Saxony. Genetic typing allowed to discriminate between isolates involved in different CSF epidemics, and was useful for tracing the origin and spread of CSF viruses. Due to the close relationship between German CS F virus isolates, epidemiological data are a prerequisite for the interpret ation of the results obtained by genetic typing. In addition, at least both genomic regions suggested here should be analysed to determine the identit y of a new isolate.