viruses Review Microtubule-Dependent Trafficking of Alphaherpesviruses in the Nervous System: The Ins and Outs Drishya Diwaker 1 and Duncan W. Wilson 1,2,* 1 Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA;
[email protected] 2 Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA * Correspondence:
[email protected]; Tel.: +1-(718)-430-2305 Received: 29 November 2019; Accepted: 15 December 2019; Published: 17 December 2019 Abstract: The Alphaherpesvirinae include the neurotropic pathogens herpes simplex virus and varicella zoster virus of humans and pseudorabies virus of swine. These viruses establish lifelong latency in the nuclei of peripheral ganglia, but utilize the peripheral tissues those neurons innervate for productive replication, spread, and transmission. Delivery of virions from replicative pools to the sites of latency requires microtubule-directed retrograde axonal transport from the nerve terminus to the cell body of the sensory neuron. As a corollary, during reactivation newly assembled virions must travel along axonal microtubules in the anterograde direction to return to the nerve terminus and infect peripheral tissues, completing the cycle. Neurotropic alphaherpesviruses can therefore exploit neuronal microtubules and motors for long distance axonal transport, and alternate between periods of sustained plus end- and minus end-directed motion at different stages of their infectious cycle. This review summarizes our current understanding of the molecular details by which this is achieved. Keywords: herpes simplex virus; pseudorabies virus; neurons; anterograde axonal transport; retrograde axonal transport; microtubules; motors 1.