APOE and Alzheimer disease: It is worth stressing though that these data and the preceding evidence for a role of HSV1 in AD, do not preclude a role for bacteria, in particular, Borrelia, Chlamydia pneumoniae, and some oral bacteria, which are probably the microbes most strongly implicated in AD (see review, Miklossy and McGeer, 2016): one or more such microbes might be involved, leading to the disease in the sizeable proportion of AD patients whose illness is not accounted for by HSV1 (in combination with APOE-ε4).