Herpes Simplex Virus 1 and 2
Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), are two members of the virus family Herpesviridae that infect humans. They are both ubiquitous and contagious and can spread when an infected person is producing and shedding the virus.
Symptoms include watery blisters in the skin, mouth, lips, or genitals. Lesions usually heal with a scab characteristic of herpetic disease. HSV-1 and -2 remain latent in the body hiding from the immune system in the cell bodies of nerves. Some people do experience sporadic episodes where the virus in the nerve cell becomes active and is transported via the nerve’s axon to the skin, where virus replication and shedding occur and cause new sores.
When the virus is active transmission happens through contact with an infectious area of the skin. It can be transmitted during latency although this is unlikely. When asymptomatic reactivation means the virus causes atypical, subtle or hard to notice symptoms that are not identified as an active herpes infection. Atypical symptoms often are attributed to yeast infections. HSV-1 is often acquired as a child, and HSV-2 is primarily a sexually transmitted infection. Both viruses can be transmitted vertically during childbirth although risk is low.
Symptoms from the primary infection with HSV are much more severe than subsequent outbreaks. The first outbreak of oral herpes carries a low risk of developing aseptic meningitis. Several glycoproteins are involved with the entry of HSV into the host cells. It evades the immune system through interference with MHC class I presentation of antigen on the cell surface. It does this through blockade of the TAP transporter. Virion host shutoff protein is important to viral replication.
HSVs may persist in a form known as latent infection, notably in neural ganglia. Whether there are visible symptoms or not the virus is shed. Colds, flu, eczema, stress, and even exposure to sunlight can reactivate the virus. It establishes a lifelong infection that can’t be eradicated from the body. Antiviral drugs are used to interfere with viral replication. There is ongoing research into a vaccine.