Bovine Herpesvirus Pathogenesis, Host Immune Responses and Available Vaccine Strategies: Are Current Management Approaches Sufficient to Counter Disease Impacts?

Bovine herpesviruses comprise a diverse group of pathogens with distinct tissue tropisms, epidemiological patterns, and clinical relevance. Bovine alphaherpesviruses 1 and 5 (BoAHV-1, BoAHV-5) are the best characterized, given their association with respiratory, reproductive, and neurological disease, whereas less is known about BoAHV-2 and the gammaherpesviruses BoGHV-4 and BoGHV-6. A central challenge for control is the capacity of these viruses to establish lifelong latent or persistent infection, evade host immunity, and reactivate under physiological or stress-related conditions. This review critically examines bovine herpesvirus pathogenesis and host immune responses, emphasizing viral tropism, latency, reactivation, innate and adaptive immune responses, and immune-evasion mechanisms. We evaluate current vaccination strategies, including modified-live, inactivated, intranasal, and gene-deleted marker vaccines, highlighting their capacity to reduce clinical disease and shedding alongside their limited ability to prevent infection, latency, or reactivation, with attention to cross-protection between BoAHV-1 and BoAHV-5 and regional differences in vaccine availability. Emerging platforms, including attenuated gene-deleted viruses and subunit, multi-epitope, DNA, and vectored vaccines, are assessed according to experimental evidence. Although several candidates improve humoral, cellular, or mucosal immunity, none has consistently achieved sterilizing immunity together with prevention of latency and transmission, reinforcing the need to integrate improved vaccination with DIVA-compatible surveillance, biosecurity, and long-term control strategies.