Vaccinia virus-expressed bovine ephemeral fever virus G but not GNS glycoprotein induces neutralizing antibodies and protects against experimental infection

Abstract

Two related glycoproteins (G and GNs ) encoded in the bovine ephemeral fever virus (BEFV) genome were expressed from recombinant vaccinia viruses (rVV). Both proteins were detected in lysates of rVV-infected cells by labelling with D-[6-3H]glucosamine or by immuno-blotting. The recombinant G protein (mol. mass 79 kDa) appeared slightly smaller than the native G protein but reacted with monoclonal antibodies directed against all defined neutralizing antigenic sites (G1, G2, G3a, G3b and G4). The recombinant G~s protein (mol. mass 90 kDa) was identical in size to the native GNs protein and failed to react by immunofluorescence with anti-G protein monoclonal or polyclonal antibodies. Antisera raised in rabbits against rVV-G or rVV-GNs both reacted strongly by immunofluorescence and immuno-electron microscopy with BEFV-infected cells. The G protein was localized intracellularly in the endoplasmic reticulum/Golgi complex and at the cell surface associated with budding and mature virus particles. The GNs protein also localized intracellularly in the endoplasmic reticulum/Golgi complex; however, at the cell surface it was associated with amorphous structures and not with budding or mature virions. Rabbits vaccinated with rVV-G developed high levels of antibodies which neutralized BEFV grown in either mammalian or insect cells. Cattle vaccinated with rVV-G also produced neutralizing antibodies and were protected against experimental BEFV infection. In contrast, rW-GNs vaccinated rabbits and cattle failed to produce neutralizing antibodies and, after challenge, BEFV was isolated from two-thirds of the vaccinated cattle.

Expression of the G1 epitope of bovine ephemeral fever virus G glycoprotein in eukaryotic cells

“…Johal et al (2008) showed that the expressed BEFV glycoprotein G by recombinant baculoviruses reacted with BEFV-neutralising monoclonal antibodies (MAbs) to all continuous and conformational antigenic sites and may be a useful vaccine antigen. Vaccinated rabbits and cattle with recombinant vaccinia viruses expressing the glycoprotein G developed high level of antibodies which neutralised BEFV in either mammalian or insect cells (Uren et al, 1994;Hertig et al, 1996). In addition, neutralising G protein monoclonal antibodies injected intraperitoneally conferred passive protection against intracerebral infection of suckling mice (Cybinski et al, 1990).…”

Location of neutralizing epitopes on the G protein of bovine ephemeral fever rhabdovirus.

“…The 81 kDa BEFV G protein is a class I transmembrane glycoprotein which contains typespecific and neutralizing antigenic sites (Cybinski et al, 1990) and induces protective immunity in cattle (Uren et al, 1994 ;Hertig et al, 1996). BEFV and other ephemeroviruses also encode a second non-structural glycoprotein (G NS ) and several other small polypeptides (Walker et al, 1992 ;Wang & Walker, 1993 ;Wang et al, 1994 ;McWilliam et al, 1997).…”

“…BEFV and other ephemeroviruses also encode a second non-structural glycoprotein (G NS ) and several other small polypeptides (Walker et al, 1992 ;Wang & Walker, 1993 ;Wang et al, 1994 ;McWilliam et al, 1997). The G NS glycoprotein is also a class I transmembrane glycoprotein which is structurally related to the G protein but has not been detected in virions and does not induce a neutralizing or protective immune response (Walker et al, 1991(Walker et al, , 1992Hertig et al, 1996).…”

Recombinant Viral Vector Vaccines for the Veterinary Use.

“…The vaccinia virus has a large number of genes which can be deleted without preventing replication in cell cultures and, in many cases, the deletion mutant has reduced virulence in animal models [18,77]. These genes have been applied as insertion sites for expression of foreign antigens and genes derived from a variety of pathogens have been stably introduced into the virus, providing potential recombinant vaccines for both veterinary and human applications, for example, genes from hepatitis B virus [76], human immunodeficiency virus (HIV) [18,129], HSV-1 [18], simian immunodeficiency virus [40], FIV [100], rabies virus [8], rinderpest virus [32], PRV [12], bovine ephemeral fever virus [36], and rabbit haemorrhagic disease virus [7]. Both humoral and cellular immune responses to the expression products from these recombinant vaccinia viruses have been demonstrated in animals and humans and, in many cases, their protective immunities have been induced in challenge studies.…”