Bovine herpesvirus-1 (BoHV-1) is a DNA virus belonging to order Herpesvirales, Herpesviridae family and the Alfaherpesvinae subfamily (Davison A J, et al., 2009) that has a wide diversity serologically indistinguishable strains. However, based on genome analyses with restriction endonucleases it has been classified into 3 subtypes: BoHV-1.1, BoHV-1.2a and BoHV-1.2b (Engels M, et al., 1981). In Colombia, multiple isolates of BoHV-1 have been subjected to molecular characterization, and most have been classified as BoHV-1.1 (Ruiz-Saenz J, et al., 2012).
BoHV-1 control is based on simple hygienic measures for the herd, quarantine periods for new cattle and BoHV-1 seronegative status for new animals. Additionally, recommended vaccines for BoHV-1 can be effective in reducing the clinical manifestations associated with viral infection and reduce virus shedding after infection, thus leading to a reduction in economic losses. However, current vaccines fail to fully protect from field BoHV-1 infection (OIE, 2004) (OIE, World organization for Animal health).
Globally, the market for BoHV-1 vaccines is broad and diverse, allowing the producers, technicians and veterinarians to choose from a wide range of vaccines. Commercially, the most widely distributed are the BoHV-1 polyvalent products commonly associated with other viral agents such as bovine viral diarrhea virus, bovine parainfluenza virus type 3, respiratory syncytial virus and bacterial agents such as Pasteurella spp, Leptospira spp, making difficult to achieve a specific immunization for BoHV-1 in areas where other agents have no epidemiological importance or where vaccination would be used as a mechanism to control a possible outbreak (Ruiz-Saenz J, et al., 2009).
Previous studies from our laboratory have allowed us to isolate and characterize the so-called "Córdoba-2" BoHV-1 strain that belongs to subtype BoHV-1.1. In one step viral growth curves it has a high virulence behavior and good glycoprotein epitope expression by Western blot (Ruiz-Saenz J, et al., 2012), suggesting that the strain is a good candidate to be used as seed for the development of an inactivated vaccine with high immunogenic potential (OIE, 2004).
The aim of the present study was therefore to develop a monovalent inactivated vaccine from a native strain of BoHV-1, and assess its potential efficiency in a rabbit model, in order to protect the bovine population against BoHV-1 infection, leading to a future possible improvement of the sanitary quality of the livestock.
An Inactivated Vaccine from a Field Strain of Bovine Herpesvirus-1 (BoHV-1) has High Antigenic Mass and Induces Strong Efficacy in a Rabbit Model
- Received Date: 07 September 2012
- Accepted Date: 17 January 2013
Abstract: Bovine Herpesvirus-1 (BoHV-1) is a DNA virus belonging to the family Herpesviridae, subfamily Alfaherpesvirinae; it is a worldwide pathogen, causing serious economic losses in livestock. In Colombia there have been multiple isolates of BoHV-1 that have been subjected to molecular characterization, classifying most of the country isolates as BoHV-1.1. In the present study we developed and evaluated an ethyleneimine binary inactivated isolate from the native BoHV-1 strain (Córdoba-2) in a rabbit model of vaccination and infection. The vaccine was evaluated in two phases, one of immunogenicity with vaccination and a booster after 21 days, and an evaluation phase of protection against challenge with a highly virulent reference strain. The results demonstrate optimum serum-conversion, with protective neutralizing antibody titers 28 days post vaccination and optimal protection against challenge with the reference strain with decreased clinical signs of infection, protection against the onset of fever and decrease of virus excretion post challenge. In conclusion, our results show the enormous potential that an immunogenic inactivated vaccine has produced from the native BoHV-1.1 strain, which produces a high antigen mass to the vaccine to induce optimal immunity and protection, and it is a strong candidate for evaluation and possible future use in different cattle populations.