The herpesvirus has a four-layered structure. They contain a core with double-stranded DNA. This is enclosed by a capsid made of capsomers. The capsid is surrounded by an amorphous protein coat known as the teugment. The outermost layer is a lipid bilayer envelope which has glycoproteins – these allow the virus to bind to cells. 

The herpes simplex virus type 1 (also known as HSV-1, human herpesvirus 1 or HHV-1) is responsible primarily for oral infections. These are both primary and secondary infections.