MULTIPLY SPLICED ENV AND NEF TRANSCRIPTS OF SIMIAN IMMUNODEFICIENCY VIRUS FROM WEST-AFRICAN GREEN MONKEY (SIVAGM-SAB)

We have characterized the spliced transcripts of nef and envelope gene s of SIVagm from African green monkey of the sabaeus subspecies, Most of the transcripts we have studied, representing the most abundant mRN A species in our assay, have undergone a specific splicing event that removes a part of the trans-activation response (TAR) element, This re gion is predicted to form a stable secondary structure (four stem-loop elements in SIVagm-sab) that affects the trans-activation of viral ge ne expression by Tat and the translation of the viral transcripts, Con trary to what is observed in other viruses, in which this R-region spl icing has also been described (e.g,, HIV-2), the LTR splicing in SIVag m-sab removes part of the first stem-loop and the following ones, near ly completely disrupting the TAR element secondary structure, Because LTR splicing seems to be a conserved feature among the strains we have characterized, these results suggest that this phenomenon could have important consequences for virus replication, pathogenicity, and laten cy.