![Microvirus](https://cdn.statically.io/img/static.wikia.nocookie.net/memoryalpha/images/f/f6/Microvirus.jpg/revision/latest/scale-to-width-down/180?cb=20161130012102&path-prefix=en)
The Acamarian microvirus
A microvirus was a genetically-engineered microorganism designed to attack cells with a certain DNA sequence. These viruses attached to parasympathetic nerves, blocking the function of the enzyme cholinesterase and with it autonomic nerve impulses.
In the mid-23rd century, Yuta of the Acamarian clan Tralesta used a microvirus to murder all but one of the members of the clan Lornak, in revenge for almost exterminating her clan. Victims of this microvirus included Penthor-Mul and Volnoth. (TNG: "The Vengeance Factor")