173. HSV-2 Isolates from Neonates with Different Clinical Outcomes Exhibit Different in Vitro and in Vivo phenotypes

Background Herpes simplex virus (HSV) infection of the neonatal brain causes severe meningoencephalitis and permanent neurologic deficits. However, infants infected with HSV at the time of birth follow different clinical courses. Some infants develop only external infection of the skin, eyes, or mouth (SEM disease), while others develop invasive infection of the central nervous system resulting in encephalitis (CNS disease). The factors that explain this clinical divergence are not well understood. While adults can be predisposed to HSV CNS infection by an innate immune defect, no such host susceptibility has been identified in neonates. Therefore, we have taken a novel approach to determine whether variations in the HSV genome contribute to infection of the neonatal brain. We recently defined the viral genetic diversity among HSV-2 isolates cultured from neonates with a range of clinical presentations. Isolates collected from neonates with CNS disease contained several unique amino acid variations in HSV proteins known to contribute to cell-to-cell spread and neurovirulence in mouse models. Methods To understand the relevance of these findings to neonatal CNS disease, we evaluated CNS disease- and SEM disease-associated neonatal HSV-2 isolates in neurologically-relevant in vitro and in vivo models. Results We found that HSV-2 isolates from neonates with CNS disease, as compared to those collected from neonates with SEM disease, displayed enhanced spread in human neuronally-differentiated SH-SY5Y or LUHMES cells and enhanced retrograde transport in rat neurons cultured in modified Campenot chambers. CNS disease-associated isolates also resulted in increased hind limb paralysis and zosteriform disease in a mouse flank scratch infection model, and increased death in a mouse direct intracerebral injection model of encephalitis. Notably, CNS disease and SEM disease-associated isolates resulted in equivalent outcomes following mouse intraperitoneal injection, suggesting similar systemic virulence. Conclusion These data suggest that virus-mediated differences in neuronal spread and transport may contribute to neurovirulence in neonatal HSV disease. Disclosures All Authors: No reported disclosures