Introduction
Herpes simplex virus (HSV) is a common virus that often causes no symptoms, but can sometimes cause skin and mucous membrane lesions. There are two types of herpes simplex viruses: HSV1 and HSV2. Both can cause infections above and below the waist, but HSV1 tends to cause infections above the waist and HSV2 tends to cause infections below the waist.
How Herpes Spreads
Herpes is most contagious when there are virus-filled lesions present, but it can also spread through asymptomatic shedding, which means that herpes viruses can be in saliva or genital secretions even when there are no signs of a cold sore or genital lesion.
The Lytic Cycle
When herpes virus lands on a new host, it dives into small cracks in the skin or mucosa and binds to epithelial cell receptors, which triggers those cells to internalize the virus. Once inside, the virus starts up the lytic cycle, which is where its DNA gets transcribed and translated by cellular enzymes which help to form viral proteins which are packaged into new herpes viruses which can leave to go off and infect neighboring epithelial cells.
The Latent Cycle
HSV1 and HSV2 also infect nearby sensory neurons and travel up their axon to the neuron’s cell body to start up the latent cycle. The sensory neurons of the face have their cell bodies in the trigeminal nuclei and those around the genitalia are located in the sacral nuclei. The herpes virus settles in these sensory neurons for life. From time to time, the herpes virus makes a few viral copies of itself and sends those virus particles back down the axon so they can get released and infect epithelial cells.
Symptoms of Herpes
In oral and genital herpes, the primary infection is most often asymptomatic. Oral herpes can cause symptoms like lesions on the palate, gums, tongue, lip, and facial area, as well as a fever and enlarged lymph nodes. In genital herpes, primary infection can cause symptoms like ulcers and pustules on the labia majora, labia minora, mons pubis, vaginal mucosa, and cervix in women, and on the shaft of the penis in men.
Conclusion
Herpes is a common virus that often causes no symptoms, but can sometimes cause skin and mucous membrane lesions. It spreads through contact with virus-filled lesions or asymptomatic shedding. The virus settles in sensory neurons for life and can cause recurrent episodes of symptoms throughout a person’s lifetime.
FAQs:
What are the symptoms of herpes?
Symptoms of herpes can include skin and mucous membrane lesions, fever, enlarged lymph nodes, and a characteristic tingling or burning sensation called a prodrome. In oral herpes, symptoms can include lesions on the palate, gums, tongue, lip, and facial area. In genital herpes, symptoms can include ulcers and pustules on the labia majora, labia minora, mons pubis, vaginal mucosa, and cervix in women, and on the shaft of the penis in men.
How is herpes spread?
Herpes is most contagious when there are virus-filled lesions present, but it can also spread through asymptomatic shedding, which means that herpes viruses can be in saliva or genital secretions even when there are no signs of a cold sore or genital lesion.
What are the two types of herpes simplex viruses?
There are two types of herpes simplex viruses: HSV1 and HSV2. Both can cause infections above and below the waist, but HSV1 tends to cause infections above the waist and HSV2 tends to cause infections below the waist.
How does the herpes virus infect a person?
When herpes virus lands on a new host, it dives into small cracks in the skin or mucosa and binds to epithelial cell receptors, which triggers those cells to internalize the virus. Once inside, the virus starts up the lytic cycle, which is where its DNA gets transcribed and translated by cellular enzymes which help to form viral proteins which are packaged into new herpes viruses.
How long does herpes stay in the body?
Herpes virus settles in sensory neurons for life and can cause recurrent episodes of symptoms throughout a person's lifetime.