Herpes Simplex Virus

Herpes simplex virus (HSV) is a double-stranded DNA virus of the Herpesviridae family that establishes lifelong latent infection in sensory nerve ganglia after primary infection. HSV-1 traditionally causes orolabial herpes (cold sores) and establishes latency in the trigeminal ganglion, while HSV-2 traditionally causes genital herpes and establishes latency in the sacral dorsal root ganglia (S2-S5), though either type can infect either site. During primary infection, the virus replicates in epithelial cells, causing cell lysis and forming the characteristic vesicular lesions. The virus then travels retrogradely along sensory nerve axons to the neuronal cell body in the ganglion, where it enters a latent state. The viral genome persists as a circular episome in the neuronal nucleus, expressing only latency-associated transcripts (LATs) that help the virus evade immune detection and prevent apoptosis of the host neuron. Periodically, the virus reactivates from latency, travels anterogradely back down the sensory nerve to the original dermatome, and causes recurrent lesions or asymptomatic viral shedding. Reactivation triggers include stress, sunlight exposure, immunosuppression, menstruation, fever, and local trauma. Primary genital herpes is typically more severe than recurrent...