Herpes simplex virus 1 infects humans, most often as
cold sores. It is very common and contagious; about 67% of the world population under the age of 50 has Herpes simplex virus 1. It is often acquired orally during childhood. It may also be sexually transmitted, including contact with saliva, such as
kissing and mouth-to-genital contact (
oral sex). The virus tends to reside in the
trigeminal ganglia. This species appears to be particularly damaging to the nervous system, and some research has attributed Herpes simplex virus 1 infection to an increased risk of developing Alzheimer's disease. The virus interacts with the components and receptors of
lipoproteins, which may lead to the development of Alzheimer's disease. However, evidence for a relationship with Alzheimer's disease is mixed. In 2011 Manchester University scientists showed that treating infected cells with antiviral agents decreased the accumulation of
β-amyloid and
tau protein, and also decreased replication of the virus. == See also ==