Cold Sore Reactivation Mechanism

Establishment of Latency

Following primary HSV-1 infection, the virus travels via retrograde axonal transport to establish latency in the sensory ganglia, specifically the trigeminal ganglion for oral infections, according to the Journal of Clinical Virology 1, 2
During latency, the virus exists in a non-replicating episomal form in neuronal nuclei, with viral lytic genes suppressed and only latency-associated transcripts (LATs) expressed, as reported by the Journal of Clinical Virology 3

Ultraviolet light exposure, specifically UV-B radiation, is a potent stimulus that induces reactivation through mechanisms involving neural pathways, with lesions typically developing 4-5 days post-exposure at or near the UV-exposed site, as found by the Journal of Clinical Virology 1, 2
Fever, or elevated body temperature, disrupts the latency-maintenance mechanisms, leading to reactivation, according to the Journal of Clinical Virology 1, 2
Psychological stress, particularly glucocorticoids, can trigger reactivation, as reported by the Journal of Clinical Virology 1, 2
Menstruation, with its associated hormonal fluctuations, serves as a reactivation stimulus, as found by the Journal of Clinical Virology 1, 2
Immunosuppression, including conditions causing low lymphocyte counts or T-cell dysfunction, increases reactivation frequency, according to the Journal of Clinical Virology and Praxis Medical Insights 1, 4

The prodromal phase, characterized by itching, burning, and/or paresthesia, occurs 12-24 hours before visible lesions, representing viral replication and migration along sensory nerves, as reported by the Journal of Clinical Virology 1, 2
Lesion evolution typically follows a sequence of erythema, papule, vesicle, pustule, ulcer, and crust, with complete healing usually within 7-10 days, according to the Journal of Clinical Virology and MMWR Recommendations and Reports 1, 2, 5
Peak viral shedding occurs within the first 24 hours after lesion onset, when most lesions are vesicular, followed by a progressive decline as lesions ulcerate and crust, as found by the Journal of Clinical Virology 1, 2

Reactivation frequency varies widely among individuals, from once every few years to multiple times monthly, with individual variation in trigger sensitivity, as reported by Eurosurveillance 6
In immunocompromised patients, reactivations produce more severe, prolonged, and extensive lesions that may involve the oral cavity or extend across the face, according to the Journal of Clinical Virology and Praxis Medical Insights 1, 2, 4