The results on the roles of MPO and LZM as important hallmark and prognostic factors of survival of rabbits suffering from infection with L. europaeus/GI.1a suggests that those antimicrobial enzymes located in neutrophils not only play a significant role in defending the host from the infection, by activating the phagocytes to actively fight with the virus, but also may serve as a prognostic marker of immune system status. The gene discussed is MPO; the disease is infection.