Pseudorabies virus deletion mutants involving the EPO and LLT genes

Abstract

An attenuated pseudorabies virus (PRV) having a reduced ability to reactivate from latency is produced by introducing (1) a genomic modification in the early protein 0 (EP0) gene whereby said virus is characterized by the inability to express the early protein 0; or (2) a genomic modification in the large latency transcript (LLT) gene whereby said virus is characterized by disruption of the synthesis of said large latency transcript; or (3) the genomic modifications described in both (1) and (2). The attenuated virus is useful in a vaccine for psuedorabies-susceptible animals, particularly swine. Swine vaccinated with a deletion mutant in the EP0/LLT overlap region displayed reduced virus shedding and fewer clinical signs than animals inoculated with a wild type virus. The deletion mutant-vaccinated swine also harbored less PRV DNA in the nervous tissue and showed reduced ability to reactivate the virus.

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