Bovine Herpesvirus type 4 infection modulates autophagy in permissive cell line

Objectives Bovine Herpesvirus type 4 (BHV-4), like other herpesviruses, induces a series of alterations in the host cell that modify the intracellular environment in favour of viral replication, survival and spread. This research examined the impact of BHV-4 infection on autophagy in BHV-4 infected Madin Darby Bovine Kidney (MDBK) cells. Methods Protein extracts of BHV-4 infected and control MDBK cells were subjected to western blot. The autophagy and apoptosis-related proteins Bcl-2, phospho Bcl-2, Bcl-xl, p53, phospho p53, Beclin 1, mTOR, phospho mTOR, p21, PI3 Kinase, Akt 1/2, and the light chain three (LC3) protein which is essential for autophagy were quantified and validated using the intracellular protein Actin as an internal standard. Moreover, in order to clarify the modulation of autophagic pathway in BHV-4 infected cells, we used lithium chloride, a well known autophagy inducer, alone or associated with BHV-4. Results Western blot analysis of virus-infected cells revealed that autophagic degradation pathway was induced in the late phase of BHV-4 infection. After 48 h post infection the proteins LC3I and II, which are essential for autophagy, were found to be markedly increased. Becline 1, AKT1/2, PI3 Kinase also increased after 48 h post infection. The use of lithium chloride in MDBK cells induced autophagy after few hours of treatment, however, in association with BHV-4 a modulation of autophagic degradation pathway, blocking lithium-induce autophagy until a late stages of virus infection, was observed. Conclusion These data demonstrate that BHV-4 infection can modulate autophagic pathway in MDBK infected cells, such effects can occur despite the presence of pro-autophagic stimuli like lithium chloride treatment. In conclusion, our finding suggest BHV-4 has developed mechanisms for modulation of autophagy that are probably part of a strategy designed to enhance viral replication and to evade the immune system. Additional studies of the relationship of autophagy with BHV-4 replication and survival are needed to understand the role of autophagy in BHV-4 pathogenesis.