ERVW-1 and infection: Following the first SIV Env protein boost at week 50, and the second boost at week 60, a significant increase in anti-Env IgG titer was observed between the Ad26/MVA and Ad26/MVA + Env groups at both time points (Fig. 2D, 4.539 and 5.811 log mean anti-Env IgG titers for Ad26/MVA and Ad26/MVA + Env groups, respectively, P < 0.0001 at week 50 post-infection, and 4.306 and 5.579 log mean anti-Env IgG titers for Ad26/MVA and Ad26/MVA + Env groups, respectively, P ≤ 0.0001 at week 62 post-infection).