In a gene expression study comparing the response of juvenile and adult rabbits to infection with RHDV GI.1 and GI.2 strains, the genes involved in activation and function of NK cells (PTPN22, VAV1, and ARRB2) were downregulated in GI.2.-infected juveniles, while they were upregulated in GI.1-infected juveniles which survived the infection, compared to adults infected with GI.1. The gene discussed is ARRB2; the disease is infection.