FIG 6.

Correlation between changes in fusion and in V1/V2 length. The ratio between fusion of the mutant and that of the corresponding WT clone was calculated for the 19 V1/V2 mutants. Results for replicates of clones, replicate infections of the same target cells with the same viral preparation, and replicate donors were successively averaged, as described in Materials and Methods. The median values of Mut/WT were used for statistical analysis. The correlation between change in length and fusion was analyzed using Spearman's rank correlation.