Polybrene is a cationic polymer used to increase the efficiency of infection of certain cells with a retrovirus

Retrovirus

A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...

 in cell culture

Cell culture

Cell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...

. Polybrene acts by neutralizing the charge repulsion between virions and sialic acid

Sialic acid

Sialic acid is a generic term for the N- or O-substituted derivatives of neuraminic acid, a monosaccharide with a nine-carbon backbone. It is also the name for the most common member of this group, N-acetylneuraminic acid...

 on the cell surface. It has other uses, including a role in protein sequencing

Protein sequencing

Protein sequencing is a technique to determine the amino acid sequence of a protein, as well as which conformation the protein adopts and the extent to which it is complexed with any non-peptide molecules...

.

The chemical name for Polybrene is 1,5-dimethyl-1,5-diazaundecamethylene polymethobromide, hexadimethrine bromide.