The Orf virus (ORFV), a member of the genus parapoxvirus of Orthopoxviridae, was found a promising alternative human and animal vector vaccine.
1. For vector construction the highly attenuated, VEGF-E negative ORFV strain D1701-VrV is used, which can be propagated in cell lines. Despite a strong and rapid immune response, the ORFV-specific immune response is short-lived allowing multiple repeated immunisations. Even in non-permissive hosts, like mice or swine, ORFV vector induces a strong humoral and cell-mediated antigen-specific immune response. ORFV recombinants expressing the glycoproteins gC and gD of PRV (Pseudorabiesvirus; Suid herpes 1) were generated and evaluated in mice as a PRV challenge model.
2. Both recombinants conferred solid protection against lethal PRV infection, mediated even by a single application of the D1701-VrVgC alone.
3. Collaborative experiments with partners 1 and 2 of that project demonstrated the immunogenic potential of both ORFV recombinants against PRV infection of pigs. Particularly, their use in prime-boost vaccination in combination with pcDNA or pSIN plasmids encoding PRV glycoproteins improved the protection against Aujeszky's disease in swine.
4. In cooperation with partner 4, PRV gB and IE (immediate early protein) expressing recombinants were constructed.
Collectively, the performed work substantiated the excellent potential of ORFV as a novel safe, efficacious and versatile vector vaccine.