A combined bovine herpesvirus 1 gB-gD DNA vaccine induces immune response in mice

Although DNA vaccines have several advantages over conventional vaccines, antibody production and protection are often not adequate, particularly in single plasmid vaccine formulations. Here we assessed the potential for a combined vaccine based on plasmids encoding the membrane-anchored or secreted forms of bovine herpesvirus type 1 (BHV-1) glycoprotein B and D (gB and gD) to induce neutralizing and cell mediated immune responses in mice. Animals were injected by intramuscular, subcutaneous and intranasal routes. Mice immunized with the combined vaccine containing the secreted forms of BHV-1 glycoproteins developed higher titers of anti-BHV-1 neutralizing antibodies, compared to wild type gB/gD combined plasmids and to single plasmid injected groups. Cellular immunity was also developed in mice immunized with combined vaccines, whereas low or no response were observed in single plasmid injected animals. The data suggest the potential use of this combined vaccine in in vivo trials of calves, in order to evaluate its protective efficacy.     

Vaccination Trials Against Bovine Herpesvirus-1

Veterinary Research Communications -     

The glycoproteins of the human herpesviruses.

The herpesvirus family contains several important human pathogens. Human herpesviruses include herpes simplex virus type 1 and 2, varicella-zoster virus, human cytomegalovirus, Epstein-Barr virus and human T-cell lymphotropic virus. The general property of herpesviruses is their ability to establish latency and to be periodically reactivated. All human herpesviruses contain a subset of genes encoding viral glycoproteins that are clearly homologous, and their similarity is significantly greater among members of the same subfamily. Membrane glycoproteins specified by human herpesviruses are important determinants of viral pathogenicity. They are exposed on the viral envelope and on the surface of infected cells. They mediate entry of the virus into cells and cell-to-cell spread of infection and also influence tissue tropism and host range. Viral membrane glycoproteins are also the most important elicitors of protective immune response and are therefore the best candidates for subunit vaccines.     

A study on latency in calves by five vaccines against bovine herpesvirus-1 infection

Four bovine herpesvirus-1 (BHV-1) commercial vaccines, three of which (vaccines B, D, E) were modified live vaccines (MLV) and one (vaccine A) identified as a live strain of BHV-1 gE negative, were used for vaccination of calves, using three calves for each vaccine. Three months after vaccination calves were subjected to dexamethasone (DMS) treatment following which virus was recovered from calves inoculated with vaccine B and from those given vaccine D. No virus reactivation was obtained in calves, which received vaccines A or E. The DNA extracted from the two reactivated viruses was subjected to restriction endonuclease analysis. The restriction pattern of the isolate obtained from calves vaccinated with vaccine D differs significantly from that of the original vaccine, whereas the reactivated virus from calves given vaccine B conserved the general pattern of the original vaccine strain. For each reactivated virus in this experiment (B and D) as well as for the isolate obtained from calves vaccinated with a further MLV (vaccine C) in a previous trial, three calves were inoculated. No clinical signs of disease were detected in any of the inoculated calves during the observation period. When the nine calves were exposed 40 days later to challenge infection with virulent BHV-1, they remained healthy and no virus was isolated from their nasal swabbings. These results indicate that some BHV-1 vaccines considered in the project can establish latency in the vaccinated calves, however, the latency does not appear to interfere with the original properties of the vaccines in terms of safety and efficacy.     

Vaccination of calves against bovine herpesvirus-1: assessment of the protective value of eight vaccines

Eight separate, but related experiments, were carried out in which groups of six calves were vaccinated with one of eight commercial vaccines. In each experiment the vaccinated calves were subsequently exposed to three calves infected with virulent bovine herpesvirus-1 (BHV-1). In each experiment, all infected donor calves developed a typical severe infectious bovine rhinotracheitis (IBR) infection and excreted virus in their nasal secretions of up to 10(8.00) TCID50/0.1 ml. One live BHV-1 gE-negative vaccine (A) and three modified live vaccines (B, C, D), administered intranasally, all protected against clinical disease. The calves vaccinated with one vaccine (C) also did not excrete virus in the nasal secretions, whereas the calves protected by vaccines A, B and D excreted virus in their nasal secretions but at low titres (10(0.66)-10(1.24) TCID50/0.1 ml). A fourth modified live vaccine (E), given intramuscularly, failed to prevent mild clinical disease in the calves which also excreted virus in the nasal secretions at titre of 10(1.00) TCID50/0.1 ml. An analogous result was given by the calves vaccinated with either of the two inactivated vaccines (F and G) or with a BHV-1 subunit vaccine (H). All calves developed mild clinical signs and excreted virus at titres of 10(2.20)-10(3.12) TCID50/0.1 ml. Calves vaccinated with C vaccine were subsequently given dexamethasone, following which virus was recovered from their nasal secretions. The virus isolates did not cause disease when calves were infected and appeared to be closely related to the vaccine strain.     

A study in calves of an immunologic relationship between herpes simplex virus and Bovid herpesvirus 2

Calves were inoculated subcutaneously with Herpes simplex virus (HSV), types 1 and 2, previously inactivated with Triton X100. Thirty-nine days later the calves were challenged either by intradermal or intravenous injection of Bovid herpesvirus 2 (BHV2).The clinical reponse of HSV preimmunized calves to BHV2 infection was milder than that in the challenge control calves, and the titer of BHV2 underwent a reduction in the preimmunized calves. BHV2 apparently enhanced the immuno-competent system of the preimmunized calves to produce antibody to HSV.From these results it appeared that HSV partially protected calves against experimentally induced BHV2 infection.