Pseudorabies virus DNA-binding protein stimulates the exonuclease activity and regulates the processivity of pseudorabies virus DNase

Mutagenesis identifies the critical regions and amino acid residues of suid herpesvirus 1 DNA-binding protein required for DNA binding and strand invasion

Herpesviral DNA-binding protein (DBP) is a unique protein involved in viral DNA replication and genomic recombination. It binds and stabilizes the single-stranded DNA. It also forms the D-loops and promotes the strand invasion. To identify the functional regions and amino acid residues required for DNA binding and D-loop formation, we characterized several DBP mutants of suid herpesvirus 1 (SuHV-1). Acetic anhydride modification assay showed that lysine residues were critical for DNA binding and D-loop formation. Replacement of highly conserved lysine residues with alanine revealed that Lys-756 and Lys-970 were critical for DNA binding, while Lys-161 participated in DNA binding and D-loop formation. Analysis of nested deleted mutants showed that N-terminal 201 amino acid residues and C-terminal 305 amino acid residues were required for D-loop formation and DNA binding, respectively. In conclusion, these findings suggested that SuHV-1 DBP contained critical regions for DNA binding and D-loop formation, and Lys-161, Lys-756, and Lys-970 were required for DNA binding or D-loop formation.

Molecular biology of pseudorabies virus: impact on neurovirology and veterinary medicine

Pseudorabies virus (PRV) is a herpesvirus of swine, a member of the Alphaherpesvirinae subfamily, and the etiological agent of Aujeszky's disease. This review describes the contributions of PRV research to herpesvirus biology, neurobiology, and viral pathogenesis by focusing on (i) the molecular biology of PRV, (ii) model systems to study PRV pathogenesis and neurovirulence, (iii) PRV transsynaptic tracing of neuronal circuits, and (iv) veterinary aspects of pseudorabies disease. The structure of the enveloped infectious particle, the content of the viral DNA genome, and a step-by-step overview of the viral replication cycle are presented. PRV infection is initiated by binding to cellular receptors to allow penetration into the cell. After reaching the nucleus, the viral genome directs a regulated gene expression cascade that culminates with viral DNA replication and production of new virion constituents. Finally, progeny virions self-assemble and exit the host cells. Animal models and neuronal culture systems developed for the study of PRV pathogenesis and neurovirulence are discussed. PRV serves asa self-perpetuating transsynaptic tracer of neuronal circuitry, and we detail the original studies of PRV circuitry mapping, the biology underlying this application, and the development of the next generation of tracer viruses. The basic veterinary aspects of pseudorabies management and disease in swine are discussed. PRV infection progresses from acute infection of the respiratory epithelium to latent infection in the peripheral nervous system. Sporadic reactivation from latency can transmit PRV to new hosts. The successful management of PRV disease has relied on vaccination, prevention, and testing.