FIG. 6.

Deduced amino acid sequence comparison of the mid-region of the SU gene of the in vivo-derived rFeLV clones with those of parental enFeLVs, various FeLV-B isolates, and FRA. Clones representative of recombination sites E, F/G, and >G (sites marked above the CFE-6 sequence) are shown. Numbers in parentheses indicate the total number of such clones examined. Amino acid sequences are presented relative to CFE-6, with dots indicating identity. Four consistent amino acid sequence differences, observed in all in vivo-derived rFeLV clones as well as three isolates of FeLV-B, GA, ST, and Rickard (R), are highlighted by boldface type (with the exception of the last position, for which only clones of recombinant site >G are highlighted) under the corresponding amino acid in CFE-6 (highlighted in gray). Other scattered amino acid changes that were detected in a few clones are also listed underneath the corresponding consensus sequence. Those positions are underlined. Numbers at both ends of the CFE-6 sequence depict the relative positions of these amino acids from the start point of the mature SU peptide. CFE-16 has a truncated SU peptide sequence because of a natural deletion (21). The reference FRA sequence is shown at the bottom, with gaps (dashes) introduced to maintain the sequence alignment.