There was a preferential expansion of the Thy1+ NK cell population in the liver of infected mice, with the representation of Thy1+ cells increasing in the liver both as a percentage of total NK cells (from 46% to 64% of total liver NK cells by day 4 post-challenge) and in their absolute number (a 10-fold increase over baseline by 7 days after infection). This evidence concerns the gene THY1 and infection.