T-cell line adaptation of human immunodeficiency virus type 1 strain SF162: effects on envelope, vpu and macrophage-tropism

Changes in co-receptor-use by human immunodeficiency virus type 1 (HIV-1) s trains are relatively rare in vivo. Here we describe two variants derived f rom the CCR5-using strain SF162, selected for replication in the C8166 T-ce ll line. Amino acid substitutions in the V3 loop conferred CXCR4-use; howev er, the loss of macrophage-tropism by one variant was due to a single mutat ion in the start codon of vpu. We discuss how V3 loop and vpu mutations acq uired by replication in T-cell lines in vitro correlate with similar change s reported for primary isolates and HIV-1 sequences in vivo.