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 .
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 .
O O O B-virus I-virus I-virus I-virus I-virus I-virus I-virus O B-other_name O B-other_name O O O O O O O O O O O B-DNA_domain_or_region O O O O O O O O O O O O O O O B-virus O