Antibody Responses to Bovine Alphaherpesvirus 1 (BoHV-1) in Passively Immunized Calves

Abstract

To date, in countries where infectious bovine rhinotracheitis (IBR) is widespread, its control is associated with deleted marker vaccines. These products lack one or more genes responsible for the synthesis of glycoproteins or enzymes. In Europe, the most widely used marker vaccine is one in which glycoprotein E (gE-) is deleted, and it is marketed in a killed or modified-live form. Using this type of immunization, it is possible to differentiate vaccinated animals (gE-) from those infected or injected with non-deleted (gE+) products using diagnostic tests specific for gE. The disadvantage of using modified-live gE-products is that they may remain latent in immunized animals and be reactivated or excreted following an immunosuppressive stimulus. For this reason, in the last few years, a new marker vaccine became commercially available containing a double deletion related to genes coding for gE and the synthesis of the thymidine-kinase (tk) enzyme, the latter being associated with the reduction of the neurotropism, latency, and reactivation of the vaccine virus. Intramuscularly and intranasally administered marker products induce a humoral immune response; however, the mother-to-calf antibody kinetics after vaccination with marker vaccines is poorly understood. This review discusses several published articles on this topic.

Keywords: IBR; calves; passive immunity.

Figure 1

The genome structure of herpesviruses comprises two regions designated Unique Long (U_L) and Unique Short (U_S). Terminal repeat (T_R) and Internal repeat (I_R) sequences may bracket unique sequences of both L and S or only S. Each region encodes different envelope glycoproteins.

Figure 2

Development of the immune response in calves.