6567
Based on the simian immunodeficiency virus (SIV) model for AIDS , loss-of-function (e.g. deletion of accessory genes such as nef ) has been forwarded as a primary approach for creating enfeebled, but replication-competent, HIV-1/SIV .
 ( DNA: nef, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( DNA: nef, None) 