APOE and infectious disease: APOE genotype has also been associated with other viral HSV-1 (herpes simplex virus type 1) and HIV-1 (human immunodeficiency virus type 1) infection,34,35 which also requires interactions with viral docking proteins.36 Future studies may determine whether APOE concentrations and APOE4 status can likewise modulate viral infectivity and severity in other infectious diseases.