195 Development of a fetal porcine model for congenital viral infections in the developing CNS

Abstract

To develop a porcine model for analysis of the effects of congenital viral infections on CNS and spinal (CSF) derived fetal neural precursor (NPC) and neural progenitor cells. Isolation of NPCs from the subventricular zone (SVZ) of the porcine brain or CSF derived from premature (day 104) and post-term (day 135) Cesarean-delivered piglets were plated in 12-well plates. Nonadherent plates were used to generate neurospheres with self-renewal capacity and for long term passages. After a 2-day incubation for neurosphere formation and removal of apoptotic debris, cells were seeded in various conditions including incubation in (1) 10% FBS, (2) Rock Inhibitor (RI)-specific inhibitor of apoptosis, (3) FBS and RI, and (4) Neurobasal media alone (control). After purification and identification of NPCs, cells were then infected with low MOI of clinically isolated first passage ZIKV HN16, then fixed and stained with Flavivirus-specific antibody (MAb 4G2) followed by FITC labeled secondary antibody staining visualization under fluorescence microscopy. Gene expression studies were also performed from RNA from ZIKV infected and mock infected samples to determine effects on genes related to NPC self-renewal and survival. The brain derived cells cultured for 4 days showed three distinct populations including NSCs, NPCs, and a mixed NSC/NPC population. After 21 days of culture, cells shifted from an NSC population toward later within the NPC lineage. Both brain and CSF cells showed relatively equal permissivity to ZIKV viral infection (Fig.1). Moreover, there was no difference in Vimentin gene expression in ZIKV infected cells, while SOX-2 and Nestin gene expression following ZIKV infection was significantly lower (p<0.05; Fig.2). The findings that Nestin expression is downregulated when comparing brain and CSF cells, particularly after ZIKA infection, is of interest since Nestin is postulated to play a role in axonal growth. This study demonstrated the ability to utilize porcine fetal NPCs in a safe and effective manner for the study of NPC development and effects of viral infections