Immune and protective abilities of ubiquitinated and non-ubiquitinated pseudorabies virus glycoproteins.

Plasmids encoding ubiquitinated (ubi-) or non-ubiquitinated (non-ubi-) glycoproteins of Pseudorabies virus (PRV) were used for vaccination of pigs. We found that the fusion of ubiquitin to viral glycoproteins increased their degradation in proteasomes in vitro, in which ubiquitin plays a key role. In the animals immunized with the plasmids encoding PRV ubi-glycoproteins and then challenged with PRV, we detected a slightly decreased cellular immune response on days 13 and 19 after immunization and a reduced nasal excretion of infectious virus on day 2 after the challenge. Afterwards, no effect of the ubiquitination of the glycoproteins on humoral or cellular immunity and on excretion of infectious virus was observed. Similarly, no effect of the ubiquitination on protective abilities of PRV glycoproteins was found.