Extracellular Vesicles Released by Bovine Alphaherpesvirus 1-Infected A549 Cells May Limit Subsequent Infections of the Progeny Virus.

Bovine alphaherpesvirus 1 (BoAHV-1) is a promising oncolytic virus that can infect the human lung carcinoma cell line A549. In an effort to adapt the virus to grow more rapidly in these cells through the serial passaging of viral progeny, we were unsuccessful. Here, we found that extracellular vesicles (EVs) secreted by BoAHV-1-infected A549 cells (referred to as EDVs) contain 59 viral proteins, including both viral structure proteins (such as gC and gD) and viral regulatory proteins (such as bICP4 and bICP22), as identified via a proteomic analysis. These EDVs can bind to and enter target cells, inhibit viral particles binding to cells, and stimulate the production of IFN-α and IFN-β in A549 cells. When EDVs are inoculated into rabbits via either the conjunctival sacs or intravenously, they can be readily detected in neurons within the trigeminal ganglia (TG), where they reduce viral replication and promote the transcription of IFN-γ. Furthermore, incorporation of the known anti-herpesvirus drug Acyclovir (ACY) into the EDVs leads to synergistically enhanced antiviral efficacy. Collectively, the EDVs exhibit antiviral effects by blocking viral binding to target cells and stimulating the innate immune response, thereby leading to the failure of the serial passaging of viral progeny in these cells, and these EDVs may serve as a promising vector for delivering drugs targeting TG tissues for antiviral purposes.