Adenovirus vs AAV – Which Viral Vector Is Right For My Research?

BioInnovatise Viral Vector Team

Updated January 20, 2025

Adenovirus and AAV are leading viral vectors in therapeutics, vaccines, and treatments, playing key roles in discovery-phase R&D, with some achieving commercialization.

Although adenovirus and AAV share similarities in capsid structure and genetic capacity, they are fundamentally different.

Understanding these differences is crucial for researchers using viral vectors to deliver genetic payloads and infect host cells. This brief overview highlights the distinctions between adenovirus and AAV as viral vectors, including the unique aspects of both adenovirus packaging and AAV packaging.

Download our Adenovirus vs AAV Guide For Viral Vector Research Applications

Adenovirus and AAV Classification Differences

Let’s quickly overview the classification differences between adenovirus and AAV:

Adenovirus (AdV) belongs to the family Adenoviridae and is a medium-sized, non-enveloped virus that can replicate independently.
Adeno-Associated Virus (AAV) belongs to the family Parvoviridae, specifically the genus Dependoparvovirus. As the genus name suggests, AAV is a “dependent” virus – it requires a helper virus (usually adenovirus or herpesvirus) to replicate effectively.

AAV Discovery/Origin: AAV was first discovered in 1965 by Bob Atchison while studying adenovirus preparations. It was initially thought to be a contaminant or byproduct of adenovirus because it was consistently found in adenovirus samples. Researchers soon realized it was a distinct virus that happened to depend on adenovirus for replication.

Adenovirus vs AAV Vector Structural Differences

The main structural differences between AAV and adenovirus are the related to the overall size, capsid structure, and genome all of which affect their cargo capacity for packaging and manufacturing (Read more AAV packaging limit / Adenovirus packaging capacity).

Size
1. Adenovirus: ~90-100 nm in diameter
2. AAV: Much smaller at ~20-25 nm in diameter
Capsid Structure
1. Adenovirus: Complex icosahedral capsid with 252 capsomeres
2. AAV: Simpler icosahedral capsid composed of 60 protein subunits (VP1, VP2, and VP3)
Genome
1. Adenovirus: Double-stranded DNA, ~36 kb
2. AAV: Single-stranded DNA, much smaller at ~4.7 kb (Learn more AAV genome packaging)

Adenovirus structure

Adenovirus and AAV Serotypes

One of the main benefits for why researchers prefer using adenovirus and AAV versus lentivirus and retrovirus is their tropism characteristic. However adenovirus and AAV have different serotype opportunities.

Adenovirus Serotypes: Over 57 human serotypes identified and these differences affect tissue tropism and immune recognition.
AAV Serotypes: At least 13 naturally occurring serotypes (AAV1-13). Many engineered variants exist and the main differences are in capsid protein sequences. These variations affect tissue tropism, transduction efficiency, immune response, and ability to evade pre-existing antibodies.

AAV vs Adenovirus - Cargo Capacity Differences

As noted above, adenovirus (~36 kb) and AAV (~4.7 kb) have different cargo capacity differences. These differences have distinct downstream considerations including:

Gene Selection & Design
- AAV – Requires careful optimization due to limited space, dual vector approach can be utilized in payload exceeds cargo capacity, and promoter selection is critical – must balance size vs activity. Same applies for regulatory elements.
- Adenovirus – Can almost always accommodate full-length genes and regulatory elements. Can include multiple genes in 1 vector.
Clinical Applications
- AAV – Best used for small genes or applications requiring long-term expression
- Adenovirus – Best suited for large genes, multiple gene delivery, and cancer therapies needing multiple payloads.
Manufacturing Impact:
- AAV – Simpler quality control due to smaller payload, more predictable packaging, more higher vector yields typically possible.
- Adenovirus – More complex quality control for large inserts, more variables to optimize in production, and may have lower vector yields with very large payloads.

AAV Packaging vs Adenovirus Packaging Differences

Before we get into the differences between AAV packaging vs adenovirus packaging, let’s review the similarities.

Similarities:

Both use helper plasmids in production systems (this is also a similarity with lentivirus packaging and retrovirus packaging).
Both require mammalian cell lines for production (also required in lentivirus packaging and retrovirus packaging).
Both undergo capsid assembly in the nucleus
Both need quality control for empty vs full capsids

Differences:

Essential Components
- AAV packaging plasmids require Rep and Cap genes, helper functions (typically from AdV or HSV), and the AAV genome possess ITRs flanking the transgene
- Adenovirus packaging plasmids require helper virus for missing functions, packaging signal, and ITRs for replication
Packaging Considerations
- AAV uses single-stranded DNA, Rep proteins drive specific packaging, has more stringent size constraints, and often has higher empty capsid rates.
- Adenovirus uses double-stranded DNA, uses specialized packaging sequences, has more flexible size accommodation, and has generally lower empty capsid rates.
Production Systems
1. AAV transfection usually involves HEK293 or HEK293T cells, requires additional helper functions, has lower yields but simpler purification, and often needs serotype-specific optimization.
2. Adenovirus transfection can involve various cell lines options (HEK293, HEK293T, PER.C6), is self-sufficient once helper provided, has higher yields but more complex purification, and has less serotype-dependent production.

Can The Same Plasmid DNA Construct Be Inserted Into An AAV Vector And An Adenoviral Vector?

Typically no. The same plasmid DNA construct typically cannot be directly inserted into both AAV and adenoviral vectors without serious modifications. Here’s a quick checklist of the plasmid DNA construct considerations when packaging in to AAV vs adenovirus.

Essential Genetic Elements Differ

AAV requires:
- ITRs specific to AAV
- Size limit of ~4.7 kb
- Specific packaging signal sequence
- Optimized regulatory elements for size
Adenovirus requires:
- ITRs specific to adenovirus
- Specific packaging signal (Ψ)
- Can accommodate up to ~36 kb
- More flexible with regulatory elements

Design Considerations

AAV Design:
- Must be highly compact
- Often needs minimal promoters
- May require mini-genes
- Limited space for enhancers
Adenoviral Design:
1. Can use full-length elements
2. More room for complex promoters
3. Can include multiple genes
4. Space for sophisticated control elements

Transfer Process To use the same gene in both systems, you would need to:

Create separate backbone plasmids
Re-clone the gene of interest
Add vector-specific elements
Optimize for each vector’s requirement
Validate packaging efficiency

If you are interested in modifying your plasmid DNA construct to be optimized for either AAV packaging or adenovirus packaging, contact our molecular cloning team.

Ensuring the appropriate viral vector for your research is incredibly important. If you are not sure which viral vector is right for your research and development, contact our viral vector team.

Learn about our quick turnaround AAV packaging services and adenovirus packaging services.

Want to learn more about the latest in AAV and adenovirus? Our colleagues at ScienceDirect (AAV and lentivirus) and Genetic Engineering & Biotechnology News (AAV and adenovirus) continuously collect and publish the latest information on viral vector based research.