NEUROTROPIC VIRUSES AND ALZHEIMER-DISEASE - INTERACTION OF HERPES-SIMPLEX TYPE-1 VIRUS AND APOLIPOPROTEIN-E IN THE ETIOLOGY OF THE DISEASE

Infectious agents have been proposed as possible etiological factors i n sporadic cases of Alzheimer disease (AD), herpes simplex type 1 viru s (HSV1) being a likely candidate. We have detected latent HSV1 in bra in from AD patients and from aged normal individuals, using polymerase chain reaction (PCR), in the regions most affected in the disease. In contrast, we have not detected another neurotropic herpes virus, vari cella tester (VZV), in any brains. We have postulated that HSV1 reacti vates periodically, and that a host or viral characteristic determines the degree of damage caused by the resulting acute infection-with muc h greater damage in the case of AD patients. We have therefore examine d a host factor-the apolipoprotein E (apoE) genotype, since the E4 all ele is a known risk factor in the disease. We have found that the risk of developing AD is much greater in those who are HSV1-positive in br ain and who possess an apoE4 allele than for those with only one of th ese factors.