Meet Herpes Simplex Virus!
HSV is a spherical, enveloped particle (150-200nm) carrying a linear, double-stranded DNA genome (~150kb) within an icosahedral capsid. The envelope and capsid are separated by protein tegument.
Several glycoproteins (gB, gC, gD, gH, gL, etc.), necessary for binding and entering the host cell, are embedded in the viral envelope. The tegument is made up of many proteins that aid in replication and immune response evasion. This pool of proteins is typically released into the cytoplasm of the infected cell. Finally, the capsid, protecting the genome, is made of 5 capsid proteins (UL6, UL18, UL35, UL38, and UL19) and is icosahedral in structure.
HSV has the ability to persist in a host cell quietly, known as latent infection. It expresses proteins that interfere with natural cell death mechanisms, ensuring their host cells don’t die. These host cells, where reservoirs form, are typically neural ganglia. Periodic symptomatic recurrences of the virus can then occur.
HSV-1, which tends to reside in the trigeminal ganglia, produces most cold sores. HSV-2, which tends to reside in the sacral ganglia, produces most genital herpes. Notice that the location of the reservoir is related to the location of symptomatic lesions.
Because HSV is able to store itself in cell reservoirs in a latent state, lifelong infections are established. General-purpose antiviral drugs, which interfere with viral replication, can be used to treat symptomatic periods (when the virus comes out of latent phase).
Posted on Instagram on April 1, 2021.