A. Photomicrographs of TH+Nissl+ neurons in the substantia nigra (SN) in C57/Bl6 mice treated with PBS, MPTP, or EcoHIV infection over time. Sections were immunostained with anti-TH and HRP-conjugated secondary antibody, and visualized with DAB. B. Photomicrographs of TH+ striatal termini (STR) following PBS, MPTP or EcoHIV coinfection. C. Total numbers of surviving dopaminergic neurons (TH+Nissl+) and non-dopaminergic neurons (TH-Nissl+) in the SN following MPTP treatment alone, EcoHIV infection alone, or EcoHIV infection followed by MPTP intoxication. Percentages of spared dopaminergic neurons are displayed on the representative bar for each treatment. Differences in means (± SEM, n=8) were determined where P<0.05 compared to PBS (a), MPTP (b), and 3 wk EcoHIV + MPTP (c). D. Relative TH density of striatal dopaminergic termini following infection. Differences in means (± SEM, n = 8) were determined where P < 0.05 compared to PBS (a), 2 wk EcoHIV (b), and 4 wk EcoHIV(c).