Construction and characterization of a glycoprotein E deletion mutant of bovine herpesvirus type 1.2 strain isolated in Brazil

Abstract

This paper describes the construction and characterization of a Brazilian strain of bovine herpesvirus type 1.2a (BoHV-1.2a) with a deletion of the glycoprotein E (gE) gene. The deletion was introduced by cotransfection of a deletion fragment containing the 5´and 3´gE flanking regions and genomic DNA of wild type BoHV-1 into bovine cells. Isolation of gE deletion mutant was performed by immunoperoxidase staining with an anti-gE monoclonal antibody. Viral clones were plaque purified and further examined by restriction endonuclesase digestion and Southern blot hybridization. This gE deletion mutant will be evaluated as a vaccinal virus, in order to determine its potential use for a differential vaccine.

Efficacy of a gE-deleted, bovine herpesvirus 1 (BoHV-1) inactivated vaccine

“…Although the presence of neutralizing antibodies in serum does not necessarily correlate with reduction of virus shedding or clinical protection in BoHV-1 vaccinated animals, induction of virus neutralizing antibodies is very often used to access immune responses to vaccination (Kramps et al 2004, Patel et al 2005, Silva et al 2007). The neutralizing antibody titers obtained after two doses of the inactivated 265gE -vaccine were higher than those detected after vaccination with one dose of the attenuated vaccine prepared with the same recombinant (Franco et al 2002a). Similar observations were reported previously with another gE -vaccine (Kaashoek et al 1995).…”

“…A gE -BoHV-1 was previously developed and tested as a live vaccine (Franco et al 2002a). As inactivated vaccines may be considered safer to use -particularly because these pose virtually no risk of virus reversion -our aim here was to evaluate the clinical, virological and serological findings on animals inoculated with an inactivated vaccine prepared with the same 265gE -recombinant, in a vaccination/ challenge experiment.…”

“…The virus was used for the construction of the recombinant virus (265gE -) as described previously (Franco et al 2002a). The SV 265 was also used in the challenge experiments.…”

“…These vaccines have an advantage over the conventional vaccines because the serological response induced by vaccination can be differentiated from that induced by the wild type virus, allowing identification of wild type virus-infected animals in a herd. Glycoprotein E (gE) is one of such non-essential proteins (Rebordosa et al 1996, Franco et al 2002a, Spilki et al 2004). Although it is conserved among other members of the Herpesviridae family, the role of gE in the in vitro growth characteristics may vary in function of the virus species and the host cell (Balan et al 1994).…”

“…In comparison to wild type viruses, gE negative recombinants (gE -) produce smaller plaque sizes in vitro, although the growth kinetics or penetration process of the virus seem not to be dependent on the presence of gE (Rebordosa et al 1996, Chowdhury et al 1999, Spilki et al 2004 In previous studies, we described the construction of a recombinant vaccine, based on a Brazilian BoHV-1 isolate, from which the gE gene was deleted. This virus was named 265gE -and evaluated in vaccination/challenge experiments (Franco et al 2002a). The live 265gE -virus based vaccine significantly reduced clinical signs of disease and virus shedding from vaccinated/challenged calves (Franco et al 2002b).…”