Estimating the Infectivity of CCR5-Tropic Simian Immunodeficiency Virus SIV mac251 in the Gut

Abstract
CD4 + T-cell depletion during acute human immunodeficiency virus infection occurs predominantly in the gastrointestinal mucosa. Using experimental data on SIV mac251 viral load in blood and CD4 + T cells in the jejunum, we modeled the kinetics of CD4 + T-cell infection and death and estimated the viral infectivity. The infectivity of SIV mac251 is higher than previously estimated for SHIV89.6P infection, but this higher infectivity is offset by a lower average peak viral load in SIV mac251 . Thus, the dynamics of target cell infection and death are remarkably similar between a CXCR4- and a CCR5-tropic infection in vivo.