S100B and viral infectious disease: From a total of 322 nef sequences sampled from the two animals, we observed 41 nucleotide base substitutions (excluding gaps) from the infecting nef sequence of SIVmac239, within the first 21 days following virus infection; out of these 41 mutations, 10 were determined to be G-to-A hypermutation patterns with APOBEC signatures (red characters in Figure 1) [25].