What is the Difference Between AAV and Lentivirus

The key difference between AAV and lentivirus is that AAV has a single-stranded DNA genome while lentivirus has an RNA genome.

Adeno-associated virus (AAV) is a DNA virus that has a single-stranded DNA genome. In contrast, lentiviruses are RNA viruses. Both AAV and Lentivirus are efficient gene delivery systems. They effectively transfer genes into mammalian cells. Moreover, they are useful in many applications, including gene knockdown, protein expression, and gene therapy.

CONTENTS

1. Overview and Key Difference
2. What is AAV 
3. What is Lentivirus
4. Similarities – AAV and Lentivirus
5. AAV vs Lentivirus in Tabular Form
6. Summary – AAV vs Lentivirus

What is AAV?

Adeno-associated virus (AAV) is a DNA virus. It has a single-stranded DNA genome that is 4.8kb in size. It is a non-enveloped, relatively simple and small virus that infects humans and other primates, causing a very mild immune response. It does not cause diseases. Even in the wild type state, AAV is not pathogenic to humans.

Similar to Lentiviruses, AAV can be engineered to use as a powerful gene delivery tool.  In fact, adeno-associated viral vectors are the leading platform in the gene therapy of human diseases. Therefore, the recombinant adeno-associated virus is a very promising gene therapy delivery vector.

What is Lentivirus?

Lentivirus is a genus of retroviruses. They belong to the family of retroviridae. Lentiviruses include human immunodeficiency virus (HIV), simian immunodeficiency virus (SIV), feline immunodeficiency virus (FIV), and equine infectious anemia virus (EIAV). Lentiviruses have an RNA genome. Therefore, they are RNA viruses. They possess the enzyme reverse transcriptase. This enzyme can convert RNA into DNA prior to integration into the host genome.

Lentiviruses are widely used as vectors in delivering DNA into mammalian cells. They possess several key features which are useful in different fields, including mammalian cell culture, animal models, and gene therapy. They are able to infect almost all types of mammalian cells. They can be used to generate stable cell lines or drive stable gene expression in organs and tissues in vivo. Lentiviruses use transduction in order to inject their genome into host cells. They can carry an insert or gene up to 8 kb in size.

Generally, lentiviruses are safe to handle. They do not convert back into pathogenic viruses. However, there are several drawbacks of lentiviruses, such as HIV origin and integration into the host genome, etc. When they randomly integrate, it can lead to insertional mutagenesis by disrupting other important genes resulting in severe outcomes. Hence, self-inactivating lentiviral vectors are designed with proper regulation of integration into the host genome.

What are the Similarities Between AAV and Lentivirus?

• AAV and lentivirus are efficient tools for gene transfer:
• They work as vectors delivering DNA into cells.
• Both use transduction to inject DNA into cells.
• They should be genetically engineered in order to use in gene therapy.

What is the Difference Between AAV and Lentivirus?

AAV is a DNA virus that is not pathogenic to humans, while lentivirus is a genus of retroviruses that are pathogenic to humans. So, this is the key difference between AAV and Lentivirus. Compared to lentivirus, AAV is relatively simple and small. Moreover, AAV can accommodate an insert of 4.5 kb while lentiviruses can accommodate an insert of 8 kb in size.

The below infographic presents the differences between AAV and lentivirus in tabular form for side by side comparison.

Summary – AAV vs Lentivirus

AAV and lentivirus are viruses that are useful as gene therapy vectors. AAV is a DNA virus that is not pathogenic to humans. It is responsible for a very mild immune response, unlike lentivirus. Lentiviruses are retroviruses that cause deadly diseases. They are RNA viruses. HIV is a lentivirus. Once engineered, lentivirus acts as an efficient gene delivery system. Thus, this summarizes the difference between AAV and Lentivirus.

Reference:

1. Naso, Michael F, et al. “Adeno-Associated Virus (AAV) as a Vector for Gene Therapy.” BioDrugs : Clinical Immunotherapeutics, Biopharmaceuticals and Gene Therapy, Springer International Publishing, Aug. 2017.
2. “Lentiviruses.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Adeno-associated virus serotype AAV2” By Jazzlw – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “ShRNA Lentivirus” By Dan Cojocari ✉·✍· – Own,  This W3C-unspecified vector image was created with Adobe Illustrator. (CC BY-SA 3.0) via Commons Wikimedia