mRFP AAV (Serotype 5)

Adeno-associated virus (AAV) is a small (~25 nm in diameter), non-enveloped, single-stranded DNA virus belonging to the family Parvoviridae (genus Dependoparvovirus). AAV was discovered in 1965 as a contaminant of a simian adenovirus preparation and its replication is dependent on co-infection with a helper virus. The icosahedral protein coat consists of three capsid proteins. These proteins (termed VP1, VP2, and VP3) share an open reading frame and differ only in their N-terminal residues. Due to a non-canonical start site and splice variants, the VP1-3 capsid proteins are expressed in a 1:1:10 ratio. AAV has successfully delivered nearly 5kb of genetic payloads to a variety of non-dividing tissues and is now arguably the leading vector for human gene therapy in vivo. mRFP AAV (serotype 5) is an adeno-associated virus vector engineered to express monomeric red fluorescent protein (mRFP) under the control of the cytomegalovirus (CMV) promoter. The mRFP gene encodes a mutant version of the red fluorescent protein (DsRed) from Discosoma sp. Conventional DsRed proteins tend to form tetramers, which can compromise cell health due to aggregation-induced cytotoxicity. The development of mRFP addressed this issue by introducing mutations that prevent tetramerization, resulting in a stable monomeric fluorescent protein that is less toxic to cells. In the mRFP AAV5 vector, the red fluorescent protein serves as an effective reporter gene, allowing researchers to monitor gene expression in real time, track cell and viral vector distribution, and assess transduction efficiency.