Supplementary Material:


                      6952       6962       6972       6982       6991       6996       7006       7016       7026
                         .          .          .          .          .          .          .          .          .
BK28            aataaaagtg agacagatag atggggattg acaaaatcat caacaacaat aacaacagca gcaccaacat cagcaccagt atcagaaaaa   [90]
predicted BK28  .......... .......... .......... .......... .........c .......... .......... .......... ..........   [90]
BK28             N  K  S   E  T  D  R   W  G  L   T  K  S   S  T  T  I   T  T  A   A  P  T   S  A  P  V   S  E  K    [30]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  T   .  .  .   .  .  .   .  .  .  .   .  .  .    [30]

                      7036       7046       7056       7066       7076       7086       7096       7106       7116
                         .          .          .          .          .          .          .          .          .
BK28            atagacatgg tcaatgagac tagttcttgt atagctcaga ataattgcac aggcttggaa caagagcaaa tgataagctg taaattcacc   [180]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ........a.   [180]
BK28             I  D  M   V  N  E  T   S  S  C   I  A  Q   N  N  C  T   G  L  E   Q  E  Q   M  I  S  C   K  F  T     [60]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  N     [60]

                      7126       7136       7146       7156       7166       7176       7186       7196       7206
                         .          .          .          .          .          .          .          .          .
BK28            atgacagggt taaaaagaga caagacaaag gagtacaatg aaacttggta ctctacagat ttggtttgtg aacaagggaa tagcactgat   [270]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [270]
BK28             M  T  G   L  K  R  D   K  T  K   E  Y  N   E  T  W  Y   S  T  D   L  V  C   E  Q  G  N   S  T  D     [90]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .     [90]

                      7216       7226       7236       7246       7256       7266       7276       7286       7296
                         .          .          .          .          .          .          .          .          .
BK28            aatgaaagca gatgctacat gaatcactgt aacacttctg ttatccaaga atcttgtgac aaacattatt gggatactat tagatttagg   [360]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [360]
BK28             N  E  S   R  C  Y  M   N  H  C   N  T  S   V  I  Q  E   S  C  D   K  H  Y   W  D  T  I   R  F  R    [120]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [120]

                      7306       7316       7326       7336       7346       7356       7366       7376       7386
                         .          .          .          .          .          .          .          .          .
BK28            tattgtgcac ctccaggtta tgctttgctt agatgtaatg acacaaatta ttcaggcttt atgcctaaat gttctaaggt ggtggtctct   [450]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [450]
BK28             Y  C  A   P  P  G  Y   A  L  L   R  C  N   D  T  N  Y   S  G  F   M  P  K   C  S  K  V   V  V  S    [150]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [150]

                      7396       7406       7416       7426       7436       7446       7456       7466       7476
                         .          .          .          .          .          .          .          .          .
BK28            tcatgcacaa ggatgatgga gacacagact tctacttggt ttggctttaa tggaactaga gcagaaaata gaacttatat ttactggcat   [540]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [540]
BK28             S  C  T   R  M  M  E   T  Q  T   S  T  W   F  G  F  N   G  T  R   A  E  N   R  T  Y  I   Y  W  H    [180]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [180]

                      7486       7496       7506       7516       7526       7536       7546       7556       7566
                         .          .          .          .          .          .          .          .          .
BK28            ggtagggata ataggactat aattagttta aataagtatt ataatctaac aatgaaatgt agaagaccag gaaataagac agttttacca   [630]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [630]
BK28             G  R  D   N  R  T  I   I  S  L   N  K  Y   Y  N  L  T   M  K  C   R  R  P   G  N  K  T   V  L  P    [210]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [210]

                      7576       7586       7596       7606       7616       7626       7636       7646       7656
                         .          .          .          .          .          .          .          .          .
BK28            gtcaccatta tgtctggatt ggttttccac tcacaaccaa tcaatgatag gccaaagcag gcatggtgtt ggtttggagg aaaatggaag   [720]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [720]
BK28             V  T  I   M  S  G  L   V  F  H   S  Q  P   I  N  D  R   P  K  Q   A  W  C   W  F  G  G   K  W  K    [240]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [240]

                      7666       7676       7686       7696       7706       7716       7726       7736       7746
                         .          .          .          .          .          .          .          .          .
BK28            gatgcaataa aagaggtgaa acagaccatt gtcaaacatc ccaggtatac tggaactaac aatactgata aaatcaattt aacggctcct   [810]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [810]
BK28             D  A  I   K  E  V  K   Q  T  I   V  K  H   P  R  Y  T   G  T  N   N  T  D   K  I  N  L   T  A  P    [270]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [270]

                      7756       7766       7776       7786       7796       7806       7816       7826       7836
                         .          .          .          .          .          .          .          .          .
BK28            ggaggaggag atccggaagt taccttcatg tggacaaatt gcagaggaga gttcctctac tgtaaaatga attggtttct aaattgggta   [900]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [900]
BK28             G  G  G   D  P  E  V   T  F  M   W  T  N   C  R  G  E   F  L  Y   C  K  M   N  W  F  L   N  W  V    [300]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [300]

                      7846       7856       7866       7876       7886       7896       7906       7916       7926
                         .          .          .          .          .          .          .          .          .
BK28            gaggataggg atgtaactac ccagaggcca aaggaacggc atagaaggaa ttacgtgccg tgtcatatta gacaaataat caacacttgg   [990]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [990]
BK28             E  D  R   D  V  T  T   Q  R  P   K  E  R   H  R  R  N   Y  V  P   C  H  I   R  Q  I  I   N  T  W    [330]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .    [330]

                      7936       7946       7956       7966       7976       7986       7996       8006       8016
                         .          .          .          .          .          .          .          .          .
BK28            cataaagtag gcaaaaatgt ttatttgcct ccaagagagg gagacctcac gtgtaactcc acagtgacca gtctcatagc aaacatagat   [1080]
predicted BK28  .......... .......... .......... .......... .......... .......... .......... .......... ..........   [1080]
BK28             H  K  V   G  K  N  V   Y  L  P   P  R  E   G  D  L  T   C  N  S   T  V  T   S  L  I  A   N  I  D     [360]
predicted BK28   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .   .  .  .   .  .  .  .   .  .  .     [360]

                      8026       8036       8046       8056     8064
                         .          .          .          .        .
BK28            tggactgatg gaaaccaaac tagtatcacc atgagtgcag aggtggca   [1128]
predicted BK28  .......... .......... ..a....... .......... ........   [1128]
BK28             W  T  D   G  N  Q  T   S  I  T   M  S  A   E  V  A     [376]
predicted BK28   .  .  .   .  .  .  .   N  .  .   .  .  .   .  .  .     [376]


FIG 1. Alignment of SIVBK28 (Env region) and deduced ancestor: Alignment of SIVmacBK28 nucleotide and amino acid sequences to the predicted BK28 nucleotide and inferred amino acid sequences. Positions where the predictions matched the known sequences are indicated by dots (.); numbers above the alignment indicate positions relative to the sequence of SIVmac239 (GenBank accession number M33262).