For analyzes, animals were anesthetized with CO 2 and perfused with 4% (w/v) paraformaldehyde (PFA). Brains were fixed in 4% PFA at least 18 h, and free-floating sections (100 mm) were prepared using a vibratome (Technical Products International) as described [33, 35] . Slices were analyzed directly by UV microscopy. Photomicrographs were taken with a digital camera (Leica). Numbers of infected eGFP-positive neurons were counted and statistical analyzes done using the student's t test and the program Prism (GraphPad, Inc.).