Neutralizing antibody response against heterologous primary isolates in child 1 over the course of infection. A) A heat map of the reciprocal log-transformed IC50 value of each plasma sample from child 1 (left) against a panel of five heterologous primary virus isolates with respective tropism (top) is shown. The reciprocal log10 IC50 value is colour-coded. The darkest colour indicates that neutralization above 50% was still detected with the highest plasma dilution tested (1/5120). The lightest colour indicates that there was no detectable neutralization above 50% with the lowest plasma dilution tested (1/40). n.d.–not done (due to lack of plasma); B) Dot-plot graphic showing the mean and standard deviation of the reciprocal log10 IC50 values obtained against R5 and X4 isolates indicated in A. Mann–Whitney U test was used to compare the median log10 reciprocal IC50 values.