The aim of the studies was differentiation of EBHS and RHD viruses by amplification of the fragment coding the first part of the capsid protein (VP60) and digestion of this fragment by restriction endonucleases. The fragments of 4 strains of EBHS (two Polish isolated in 1992 and 1998; two standard Italian and French) and 5 strains of RHD (Polish strains isolated in 1988, 1994, 1997 and 1998) viruses were amplified by RT-PCR with the use of primers selected for each virus. The specific fragments of 726 bp of EBHS and 734 bp of RHD viruses were demonstrated after amplification with the use of primers selected for each virus. Negative results were obtained when primers selected for the RHD virus were used to amplify the fragment of EBHS virus and on the contrary. The hybridisation by the Southern blot method revealed the cross reaction of DIG-Iabelled probes prepared for each virus. The endonucleases BamH I and Pst I were used in the restriction analysis of fragments. The 734 bp fragments of all strains of RHD virus digested by BamH I and Pst I enzymes demonstrated the same restriction profiles. The 726 bp fragments of strains of EBHS virus were not digested by Pst I, whereas in two strains (standard Italian and Polish isolated in 1988) after digestion with BamH I different restriction profiles in comparison with RHD virus were demonstrated.
Polish strains of EBHS virus isolated in 1992 (NP11/92) and in 1988 (L/98) were compared with standard Italian and French strains by restriction analysis of fragment coding the first part of capsid protein (VP60). The 726 bp fragment of capsid protein gene of strains tested was obtained by RT-PCR. The digestion of 726 bp fragments by BamH I endonuclease, revealed the same restriction profile for strain L/98 as Italian standard strain. These fragments of strain NP11/92 and French standard strain were not digested by BamH I. Endonuclease Sma I did not digested the amplified fragment of strains tested. The 726 bp fragment of strain L/98 demonstrated different restriction profiles for BsuR I and Hpa II enzymes in comparison with strain NP11/92 and standard strains. These results revealed differences in restriction profiles of fragment coding the first part of VP60 of Polish strains in comparison with standard strains and also between two Polish strains isolated in 1992 and 1998. These differences suggest the possibility of genotype changes of Polish EBHS strains isolated in different years.