This study aimed (1) to map the immunogenic epitopes (B and T cells) within the major BCoV structural proteins. These epitopes are believed to induce a robust im-mune response through the interaction with major histocompatibility complex (MHC class II) molecules (2) to design some novel BCoV multi-epitope-based vac-cines. To achieve these goals, we applied several integrated In-silico prediction computational tools to map these epitopes within the major BCoV structural pro-teins. The predicted epitopes were linked to some immunostimulants such as Toll-like receptors-2 (TLR2) and TLR-4. The tertiary structure of each epitope was modeled through the Alpha fold-2 colab machine learning tools. The stability and purity of each epitope were assessed using the Ramachandran plot and the Z Score values. Each multiepitope-based vaccine candidate conjugated with the Chlorotox-in B toxin as an adjuvant. We designed the vaccine constructs using various expres-sion vectors. We also predicted the affinity binding of these vaccines with the target protein using molecular docking. Our designed multiepitope vaccine candidates per each BCoV structural protein showed high antigenicity, immunogenicity, non-allergic, non-toxic, and high water solubility. Further studies are highly en-couraged to validate the efficacy of these novel BCoV vaccines in the natural host.

Bovine coronavirus (BCoV) is one of the most common pathogens affecting cattle of all ages. BCoV possesses multiple tissue tropism in cattle, particularly in the respiratory and enteric tracts of the affected animals. Viral entry is a crucial step in the replication cycle of all viruses, including BCoV. The process of viral entry requires the orchestration between several proteins from the virus and the host side. The coronavirus spike glycoproteins contributed substantially to other viral infections and the molecular pathogenesis of coronaviruses, including BCoV. Meanwhile, among all corona-viruses, the hemagglutinin esterase enzyme is found in only BCoV and the human corona-virus-OC43 (HCoV-OC43). The viral receptors are among the key players in the viral entry and could explain the viral tropism, at least in part. The presence of some host cell proteases also en-hances the virus replication from the entry until the release of the virus from the host cells. Previous studies have shown that the 9- O-acetylated sialic acids could potentially act as receptors for the BCoV. However, little is known about the BCoV receptors and if other co/receptors might be needed to ensure viral entry to the host cells. In addition to that, the roles of other host cell proteases, such as Furin and TMPRSS2, in BCoV infection have not yet been well studied. The main objectives of the current study are to identify some novel receptors for BCoV and some host cell proteases that might enhance virus replication. We used some in silico docking tools to predict some new BCoV receptors out of some known other coronavirus receptors (ACE-2, NRP1, DPP4, APN, and CEACAM1). Our results postulated the potential actions of the host Furin and TMPRRS2 enzymes in the activation of BCoV-S glycoprotein, which potentially enhances BCoV replication. Our modeling confirms the high binding affinities of both the 9- O-acetylated sialic and the NRP1 with the BCoV-S and BCoV-HE compared to the ACE-2, DPP4, and CEACAM-1, suggesting their roles as receptors for BCoV. Our prediction models show the potential bindings of the Furin and TMPRSS2 to the BCoV-S polybasic cleavage site (RRSRR|A). To our knowledge, this is the first study to investigate the bovine coronavirus interaction with some other potential host receptors, particularly ACE-2, NRP1, DPP4, APN and CEACAM1, TMPRSS2, and the bovine Furin protease.