Several studies have found an association between Apolipoprotein E (APOE), a lipid-binding protein involved in the transport of dietary fats and sterols, and Herpes Simplex Virus type 1 (HSV-1) infection. In one study, researchers found an association between a genetic variant of the APOE gene, the E4 allele, and a history of symptomatic HSV-1 infection. Researchers analyzing brain tissue also found HSV-1 DNA more often in samples from carriers of the E4 allele. Taken together, these findings suggest that carriers of the E4 allele might be more prone either to HSV acquisition or reactivation of latent HSV infection, both of which could lead to increased transmission risk.
To further investigate this connection and to explore a potential connection between APOE and the related herpes virus HSV-2, VIDI affiliate investigators Dr. David M. Koelle and Dr. Anna Wald, in conjunction with VIDI joint assistant member Dr. Amalia Magaret and other colleagues, followed 200 adult subjects with HSV-1 (oral herpes) and/or HSV-2 (genital herpes) infection. The researchers determined which APOE alleles participants carried and asked the volunteers to collect daily genital or oral swabs and report any lesions for at least one month. They then looked for an association between APOE genotype, levels of viral shedding and HSV symptoms.
They found that HSV-1-positive participants who carried an E4 allele were more likely to have longer outbreaks of oral lesions. However, they found no correlation between the presence of an E4 allele and amount of oral or genital viral shedding, or the frequency of genital lesions. The study suggests that, contrary to what was previously believed, APOE genotype is unlikely to have a significant effect on HSV transmission in the population.
APOE genotype is associated with oral herpetic lesions but not genital or oral herpes simplex virus shedding. Koelle DM, Magaret A, Warren T, Schellenberg GD, Wald A. Sex Transm Infect. 2010 Apr 21.