Development of porcine adenovirus-3 as an expression vector

Porcine adenovirus-3 (PAV-3) was developed as an expression vector using ho mologous recombination in Escherichia coli BJ 5183, As a prerequisite, the complete genome of PAV-3 was first introduced as a Pad restriction fragment into a bacterial plasmid. The plasmid, when Pad restricted and transfected into swine testicular cells, produces an infectious virus. The potential o f this procedure was demonstrated by the construction of several PAV-3 reco mbinants. Part of the E3 region, which is nonessential for virus replicatio n under cell culture conditions, was identified and deleted from the virus genome. The gene for glycoprotein D (gD) of pseudorabies virus (PRV), which elicits PRV-neutralizing antibodies in pigs, was cloned and expressed from the E3 region of PAV-3, A 50 kDa polypeptide was identified in recombinant PAV-3-infected cell lysates by immunoprecipitation assays using go-specifi c monoclonal antibodies. In another experiment, a region between the right inverted terminal repeat and the promoter of the E4 region was used to clon e and express the chloramphenicol acetyltransferase (CAT) gene under the co ntrol of SV40 immediate early promoter. CAT gene expression was observed ir respective of the orientation of the CAT gene. These results indicate that the helper-independent recombinant PAV-3 could be used as an expression vec tor and has potential as a recombinant vaccine vector in pigs.