Commensal vs. Mutualistic Partnership (image) Hokkaido University Share Print E-Mail Caption To complete their life cycles, defective pararetrovirus (PRV) species have evolved to form partnerships which are maintained by frequent exchanges of their noncoding regulatory sequences (NRSs). Credit Chen S. et al., PLOS Pathogens, June 29, 2017. Usage Restrictions This image is copyrighted and can be used for reporting this press release if properly credited. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.