Repair of the UL21 Locus in Pseudorabies Virus Bartha Enhances the Kinetics of Retrograde, Transneuronal Infection In Vitro and In Vivo

Department of Molecular Biology, Princeton University, 314 Schultz Laboratory, Princeton, NJ 08544, USA.
Journal of Virology (Impact Factor: 4.44). 12/2008; 83(3):1173-83. DOI: 10.1128/JVI.02102-08
Source: PubMed


The attenuated pseudorabies virus (PRV) strain Bartha contains several characterized mutations that affect its virulence and ability to spread through neural circuits. This strain contains a small genomic deletion that abrogates anterograde spread and is widely used as a retrograde-restricted neural circuit tracer. Previous studies showed that the retrograde-directed spread of PRV Bartha is slower than that of wild-type PRV. We used compartmented neuronal cultures to characterize the retrograde defect and identify the genetic basis of the phenotype. PRV Bartha is not impaired in retrograde axonal transport, but transneuronal spread among neurons is diminished. Repair of the U(L)21 locus with wild-type sequence restored efficient transneuronal spread both in vitro and in vivo. It is likely that mutations in the Bartha U(L)21 gene confer defects that affect infectious particle production, causing a delay in spread to presynaptic neurons and amplification of infection. These events manifest as slower kinetics of retrograde viral spread in a neural circuit.

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    • "PRV-267 was constructed as follows. We first constructed PRV-266, a PRV-Bartha strain expressing mRFP-VP26 and diffusible eGFP, through co-infection of porcine kidney epithelial (PK-15) cells with PRV-152 (a PRV-Bartha strain encoding a diffusible eGFP under an immediate-early hCMV promoter from the US4 locus, [22]) and PRV-756 (a mRFP-VP26 fusion protein, [23]). VP26 is a surface capsid protein encoded by the UL35 gene and the fusion protein incorporating mRFP labels viral capsids intensely, thereby providing a unique marker of neurons replicating PRV-267. "
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