Fomivirsen is an antiviral drug

Antiviral drug

Antiviral drugs are a class of medication used specifically for treating viral infections. Like antibiotics for bacteria, specific antivirals are used for specific viruses...

. It is used in the treatment of cytomegalovirus retinitis

Cytomegalovirus retinitis

Cytomegalovirus retinitis, also known as CMV retinitis, is an inflammation of the eye's retina that can lead to blindness.-Presentation:...

 (CMV) in immunocompromised patients, including those with AIDS

AIDS

Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...

. It was licenced by the FDA for CMV in Aug 1998.

It is a synthetic 21 member oligonucleotide

Oligonucleotide

An oligonucleotide is a short nucleic acid polymer, typically with fifty or fewer bases. Although they can be formed by bond cleavage of longer segments, they are now more commonly synthesized, in a sequence-specific manner, from individual nucleoside phosphoramidites...

 with phosphorothioate

Thiophosphate

A thiophosphate is a family of compounds and anions with the general chemical formula PS4-xOx3- . The state of protonation is usually not specified. They could be bound to as many as three protons for the neutral H3PS4-xOx species. Two protons correspond to the related monoanions, and one...

 linkages (which are resistant to degradation by nuclease

Nuclease

A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Older publications may use terms such as "polynucleotidase" or "nucleodepolymerase"....

s) and has the sequence:

• 5'-GCG TTT GCT CTT CTT CTT GCG-3'

Mechanism

It is an oligonucleotide

Oligonucleotide

An oligonucleotide is a short nucleic acid polymer, typically with fifty or fewer bases. Although they can be formed by bond cleavage of longer segments, they are now more commonly synthesized, in a sequence-specific manner, from individual nucleoside phosphoramidites...

 that blocks translation

Translation (genetics)

In molecular biology and genetics, translation is the third stage of protein biosynthesis . In translation, messenger RNA produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein...

 of viral mRNA by binding to a coding segment of a key CMV gene. It was the first antisense

Antisense therapy

Antisense therapy is a form of treatment for genetic disorders or infections.When the genetic sequence of a particular gene is known to be causative of a particular disease, it is possible to synthesize a strand of nuc acid that will bind to the messenger RNA produced by that gene and inactivate...

antiviral approved by the FDA.