Host Immune Response to Bovine Viral Diarrhea Virus (BVDV): Insights and Strategies for Effective Vaccine Design

Bovine viral diarrhea (BVD) is caused by bovine viral diarrhea virus (BVDV). The disease incurs $1.5-2.5 billion/year and $0.50 to $687.80/cow loss in beef and dairy farms respectively. This review aims to provide insights into the interaction of BVDV with host immunity, currently available vaccines, and strategies used to advance the vaccines. The virus causes immunosuppression by interfering with the innate and adaptive immune systems in a strain and biotypes-dependent manner. Interferon production, apoptosis, neutrophil activity, macrophages, and antigen-presenting cells are significantly affected during viral infection. Maternal antibodies (MatAb) are crucial to protect calves from early infection. However, the MatAb is counterproductive during vaccination against the virus. There are several types of licensed commercial inactivated or modified live vaccines, most of which are made of cytopathic BVDV 1 and 2 and the BVDV 1a subtype. Subunit and marker vaccines are made of E2, Erns, and NS3 proteins in combination with modern adjuvants, respectively. Such types of vaccines are not yet licensed and are in the experimental stage. The limitations of currently available conventional vaccines are minimal or lack of cross-protection, production costs, safety concerns, and inefficiency in provoking both humoral and cellular immune systems. To alleviate these limitations, the knowledge of developing next-generation vaccines using appropriate viral proteins and the use of modern adjuvants is promising.