Other data too have provided confirmation—sometimes indirect, from very diverse types of approach (Table 2 and see review, Itzhaki, 2014), including studies on HSV1-infected APOE-transgenic mice or APOE-transfected cell cultures, GWAS, epidemiological investigations on anti-HSV1 IgG and IgM antibodies in serum from AD patients, or on infectious burden, and measurement of IgG avidity index (Agostini et al., 2016) as an indicator of reactivation (IgG presence indicates infection with HSV1, and IgM indicates HSV1 recent reactivation). Here, APOE is linked to Alzheimer disease.