BIOLOGICAL CHARACTERIZATION OF REV VARIATION IN EQUINE INFECTIOUS-ANEMIA VIRUS

Sequence analysis identified significant variation in the second exon of equine infectious anemia virus (EIAV) rev. Functional analysis indi cated that limited amino acid variation in Rev significantly altered t he export activity of the protein but did not affect Rev-dependent alt ernative splicing. EIAV Rev can mediate export through two independent cis-acting Rev-responsive elements (RREs), and differences among Rev variants were more pronounced when both RREs were present. Variation i n Rev may be an important mechanism for regulation of virus replicatio n in vivo and may contribute to changes in clinical disease.