Herpes Simplex Virus 1: An Overview

Herpes simplex virus 1 (HSV-1), more commonly known as oral herpes, is a sexually transmitted infection that has been documented as far back as ancient Greece. The most common symptoms are cold sores and ulcers in and around the mouth, although more serious symptoms like brain swelling, called encephalitis, may occur. Children and immunocompromised individuals may experience worsened symptoms. For many, no symptoms may manifest at all, however, even with no symptoms, an individual may still be able to spread the virus While not known how much of the population is infected for sure, estimates can be as high as 90%1.

As a virus, HSV-1 attacks the body by entering cells and rewiring cell function, inducing the cell to replicate the virus. Special molecules on the outside of the virus, called glycoproteins, allow it to enter the cell as well as protect it from certain immune responses, making it difficult for the body to fight2. HSV-1 is also unique in that it undergoes periods of latency, in which it lies dormant within the body and does not replicate. Stress, other infections, and treatments like chemotherapy may trigger HSV-1 to reactivate at the site of initial infection, which is why visible symptoms of reinfection tend to stay in or near the mouth.  For some individuals, the virus will remain latent for the rest of their life.

Latent HSV-1 typically localizes in brain tissue and new studies indicate that HSV-1 may worsen symptoms of some neurodegenerative diseases like Alzheimer’s as well as interact with other neurological and mental disorders like autism, bipolar disorder, chronic fatigue syndrome, depression, Parkinson’s disease and anorexia3. While there is currently no cure for HSV-1, new advancements in gene editing as well as studies in specialized forms of cholesterol as HSV-1 inhibitors show promise as possible treatments4,5.

 

 

 

 

 

 

Works cited:

  1. Looker, K. J.et al. Global and Regional Estimates of Prevalent and Incident Herpes Simplex Virus Type 1 Infections in 2012. PLoS ONE 10, e0140765 (2015).
  2. Spear, P. G. Herpes simplex virus: receptors and ligands for cell entry.Cellular Microbiology 6, 401–410 (2004).
  3. Carter, C. J. Susceptibility genes are enriched in those of the herpes simplex virus 1/host interactome in psychiatric and neurological disorders.Pathog Dis 69, 240–261 (2013).
  4. Lin, C.et al. Increasing the Efficiency of CRISPR/Cas9-mediated Precise Genome Editing of HSV-1 Virus in Human Cells. Sci Rep 6, (2016).
  5. Cagno, V.et al. Inhibition of herpes simplex-1 virus replication by 25-hydroxycholesterol and 27-hydroxycholesterol. Redox Biol 12, 522–527 (2017).

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