Influence of Infectious Pancreatic Necrosis Virus and Yersinia ruckeri Co-Infection on a Non-Specific Immune System in Rainbow Trout (Oncorhynchus mykiss)

Abstract

Background: The IPNV is one of the most common viral pathogens of rainbow trout (Oncorhynchus mykiss), while Y. ruckeri infections are widespread among bacterial agents. The current study aimed to determine the influence of IPNV and Y. ruckeri co-infection on a non-specific immune response. Methods: Two experiments were conducted. The first experiment determined the changes in non-specific immunity parameters upon the simultaneous occurrence of IPNV and Y. ruckeri infection. In the second experiment, infection with the IPNV was performed two weeks before Y. ruckeri infection. The level of total protein, gamma globulins, the activity of lysozyme and ceruloplasmin, as well as the metabolic activity and potential killing activity of phagocytes were measured: 0, 24 h, 72 h, 7 days, 14 days, and 21 days after co-infection. Results: A differentiated effect on the parameters of the non-specific immune response was shown between single infections with the IPNV and Y. ruckeri as well as co-infection with these pathogens. Conclusions: The immune response in the course of a co-infection depended on the time between infections. IPNV infection causes lysozyme activity suppression, which may lead to secondary bacterial infections.