Of the naive RAG1ko mice that received 1×105 primed Thy1+ liver NK cells, 41% (9/22) were able to resolve a systemic, lethal vaccinia virus challenge infection, while only 2% (1/49) of RAG1ko mice that received other purified NK cell subpopulations were able to resolve and survive infection (Fig. 7). Here, THY1 is linked to infection.