What is the Difference Between Adeno-associated Viral Vector and Adenoviral Vector

The key difference between adeno-associated viral vector and adenoviral vector is that adeno-associated viral vector is a single-stranded DNA viral vector while adenoviral vector is a double-stranded DNA viral vector.

Adeno-associated viral vector and adenoviral vector are two viral vectors. Viral vectors are very important tools to deliver transgenes to the host cells. This process can be performed in living cells or cell cultures. Viruses have a special mechanism to transport their genomes into the host cells they infect. The delivery of a transgene to a host is known as transduction. Molecular biologists first used this technique in the 1970s.

CONTENTS

1. Overview and Key Difference
2. What is Adeno-associated Viral Vector  
3. What is Adenoviral Vector
4. Similarities – Adeno-associated Viral Vector and Adenoviral Vector
5. Adeno-associated Viral Vector vs Adenoviral Vector in Tabular Form
6. Summary – Adeno-associated Viral Vector vs Adenoviral Vector

 What is Adeno-associated Viral Vector?

Adeno-associated viral vector (AAVV) is a single-stranded DNA viral vector. Adeno-associated virus is a small DNA virus that infects humans and other primate species. It does not cause any disease, but it does cause a very mild immune response. Generally, adeno-associated viruses can infect dividing and non-dividing cells. It is capable of incorporating its genome into the host cell. However, it mostly stays as episomal, i.e., replicating without incorporation into the chromosome. Thus, adeno-associated viral vector performs long and stable expression of transgenes. These features make the adeno-associated virus a very attractive viral vector for molecular biological research. Moreover, at the moment, it is used as an effective viral vector in gene therapy.

It’s important to note that adeno-associated viral vectors can only deliver 5 kb transgene to the host, which is considerably small. Furthermore, this virus packages a single-stranded DNA and requires the process of second-strand synthesis. Second strand synthesis slows down the expression in the host cell. Therefore, scientists made a modified adeno-associated viral vector called self-complementary adeno-associated viral vector that packages both strands, which anneal together to form double-stranded DNA. This allows rapid expression in the host cell.

What is Adenoviral Vector?

Adenoviral vector is a double-stranded DNA viral vector. Adenoviral DNA does not integrate into the genome and is not replicated during cell division. This limits their use in basic research. However, some specialized cells such as HEK293 can facilitate adenovirus replication in host cells. The primary application of adenoviral vectors is in gene therapy and vaccination. There are several advantages of using adenoviral vectors. The relatively large size and well-characterized genome of adenovirus are easy to manipulate genetically.

Moreover, the adenoviral vector is safe, and it infects a wide range of dividing and non-dividing cells. Unlike lentivirus and retrovirus, the risk of insertion mutagenesis is much less in adenovirus as it does not integrate viral genome to host genome. The only problem with this vector is neutralizing antibodies that inactivate them in hosts like humans. Chimpanzee adenovirus vector is well tolerated to these immune responses. Chimpanzee adenovirus vector is a well-known adenoviral vector, which is used as a vector to transport the SARS-COV-2 spike gene in the Oxford AstraZeneca COVID vaccine.

What are the Similarities Between Adeno-associated Viral Vector and Adenoviral Vector?

• Adeno-associated viral vector and adenoviral vector are two viral vectors.
• Both are non-enveloped viruses.
• They are DNA-based.
• They can infect diving and non-dividing cells.
• Moreover, they can be replication-defective.
• Both viral vectors are used in gene therapy.

What is the Difference Between Adeno-associated Viral Vector and Adenoviral Vector?

An adeno-associated viral vector is a single-stranded DNA viral vector, while an adenoviral vector is a double-stranded DNA viral vector. So, this is the key difference between adeno-associated viral vector and adenoviral vector. Moreover, an Adeno-associated viral vector can only deliver 5 kb foreign DNA to the host cell while an adenoviral vector can deliver up to 36 kb foreign DNA to the host cells.

The following infographic lists the differences between adeno-associated viral vector and adenoviral vector in tabular form for side by side comparison.

Summary – Adeno-associated Viral Vector vs Adenoviral Vector

Viral vectors are efficient tools to deliver transgenes to host cells. Adeno-associated viral vector and adenoviral vector are two very popular viral vectors currently used in gene therapy. The adeno-associated viral vector is a single-stranded DNA viral vector while the adenoviral vector is a double-stranded DNA viral vector. Thus, this is the key difference between adeno-associated viral vector and adenoviral vector.

Reference:

1. “Adeno Associated Virus Vector.” An Overview | ScienceDirect Topics.
2. “Adenovirus Vector.” 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. “Adenovirus-mediated gene therapy” By 331pten – Drawing (CC BY-SA 3.0) via Commons Wikimedia