Herpes simplex virus type 1 corneal infection results in periocular disease by zosteriform spread. Summers BC, Margolis TP, Leib DA. J Virology 2001;75:5069–5075.

Abstract

In humans and animal models of herpes simplex virus infection, zosteriform skin lesions have been described which result from anterograde spread of the virus following invasion of the nervous system. Such routes of viral spread have not been fully examined following corneal infection, and the possible pathologic consequences of such spread are unknown. To investigate this, recombinant viruses expressing reporter genes were generated to quantify and correlate gene expression with replication in eyes, trigeminal ganglia, and periocular tissue. Reporter activity peaked in eyes 24 hours postinfection and rapidly fell to background levels by 48 hours despite the continued presence of viral titers. Reporter activity rose in the trigeminal ganglia at 60 hours and peaked at 72 hours, concomitant with the appearance and persistence of infectious virus. Virus was present in the periocular skin from 24 hours despite the lack of significant reporter activity until 84 hours postinfection. This detection of reporter activity was followed by the onset of periocular disease on day four. Corneal infection with a thymidine kinase-deleted reporter virus displayed a similar profile of reporter activity and viral titer in the eyes, but little or no detectable activity was observed in trigeminal ganglia or periocular tissue. In addition, no periocular disease symptoms were observed. The authors conclude that these findings demonstrate that viral infection of periocular tissue and subsequent disease development occurs by zosteriform spread from the cornea to the periocular tissue via the trigeminal ganglion, rather than by direct spread from cornea to the periocular skin. Clinical evidence is discussed suggesting that a similar mode of spreading and disease occurs in humans following primary ocular infection.—Thomas J. Liesegang