The study aimed to analyse selected parameters of non-specific humoral immunity (myeloperoxidase - MPO activity, as well as lysozyme - LZM concentration and activity) in rabbits infected with three German (Hagenow, Frankfurt, Triptis) strains of the RHD virus with different biological properties. The results of the study showed that biological properties (i.e. different reactivity in the HA test and formation of antigen variant), have impact on the analysed non-specific humoral immunity factors, as antigen variant Triptis causing high mortality at a very short time was the most immunogenic strain, while the strain with variable haemagglutination capacity Hagenow proved to be the least immunogenic strain.