The project has resulted in a manuscript examining results from studies satifying the following criteria: (1) known donors infected recipients (e.g., mothers infected breast-feeding babies or viral stock infected macaques); and (2) the recipient sequences are from acute phase of infection, as defined from Fiebig staging. Such studies provide data relevant to a question posed by Drs. Lewis and Devico: are the sequences of the infecting and non-infecting immunodeficiency virus particles in a inoculum statistically distinguishable? Statistical analysis indicates that the founder viruses of the SIV infection differ significantly from the typical virions in the stock inoculum. Moreover, the statistical differences can be assigned to specific residues in the viral attachment (Env) protein. Although ethical restrictions make HIV data less useful to our research purposes, some HIV data provide relevant anecdotal support to our biological hypotheses, and our statistical overview of several studies indicates that some results from some animal trials require reinterpretation.