Correction: Co-Infection with the Friend Retrovirus and Mouse Scrapie Does Not Alter Prion Disease Pathogenesis in Susceptible Mice

• Pascal Leblanc, 
• Kim Hasenkrug, 
• Anne Ward, 
• Lara Myers, 
• Ronald J. Messer, 
• Sandrine Alais, 
• Andrew Timmes, 
• Suzette A. Priola