In PLoS Biology this week, a team led by investigators at Harvard reports that the TRIM5 gene suppresses cross-species transmission of simian immunodeficiency viruses of sooty mangabeys "and selects for emergence of resistant variants." The team analyzed cross-species transmission of SIVsm in two groups of rhesus macaques and "found a significant effect of TRIM5 genotype on viral replication levels." In SIVsmE543-3-infected animals, the "TRIM5 genotype correlated with approx