Phylogenetic reconstruction of intrapatient evolution of human immunodeficiency virus type 1: predominance of drift and purifying selection

The intra-host evolution of 73 human immunodeficiency virus type 1 quasispecies was analysed by split decomposition analysis. Non-synonymous and synonymous nucleotide substitutions were counted along the shortest path connecting all sequences and compared with the numbers expected under the assumption of a random model of mutation. For the majority of substitutions, drift and negative selection seemed to prevail.