The Collaborative International Dictionary of English v.0.48:

HS1 \HS1\, HSV-1 \HSV-1\, HSV-I \HSV-I\n.
   1. Herpes simplex 1, a herpes virus that causes oral herpes;
      also called type I Herpes.

   Syn: herpes simplex 1.
        [WordNet 1.5] HSV-2
        HS2