Human alpha-defensins HNP1 and HD5 neutralize AAV gene therapy vectors through distinct mechanisms — one blocks cell binding, the other acts post-binding.
2 mechanismsHD5 blocks AAV cell binding while HNP1 neutralizes AAV after it has already attached to cells
What the researchers found
HD5 prevents AAV cell binding while HNP1 neutralizes AAV post-binding — two distinct innate immune mechanisms that limit gene therapy efficacy.
Why it matters
Understanding how defensins block AAV helps design gene therapy vectors that evade innate immunity, improving treatment success rates.
The numbers in context
Both HNP1 and HD5 inhibit AAV2 and AAV6 at low micromolar concentrations; block VP1 unique domain externalization; prevent nuclear entry.
How the study worked
In vitro AAV infection assays with purified human defensins HNP1 and HD5, measuring binding, entry, and infection of AAV2 and AAV6.
Who was studied
N/A (cell culture with human alpha-defensins and AAV vectors)
What this study cannot tell us
In vitro study — defensin concentrations in relevant tissues in vivo may differ. Only AAV2 and AAV6 serotypes tested.
How to read the evidence
In vitro mechanistic study — high scientific rigor for understanding defensin-AAV interactions, limited direct clinical translatability.
When this study was published
Published in 2025 in PLoS Pathogens, advancing understanding of innate immune barriers to gene therapy.
The bigger picture
Overcoming both adaptive and innate immune barriers is essential for gene therapy to reach its full clinical potential.
Questions still open
- Can AAV vectors be engineered to resist defensin neutralization?
- Do defensin levels explain patient-to-patient variability in gene therapy efficacy?
Common questions
Why does the immune system attack gene therapy?
Can gene therapy be improved to overcome defensins?
Read the original research
Mechanisms of AAV neutralization by human alpha-defensins.
PLoS pathogens, 21(7), e1013283
Citation
Porter, Jessica M; Hulce, Kaitlin R; Oswald, Mackenzi S; Busuttil, Kevin; Emmanuel, Shanan N; Bennett, Antonette; McKenna, Robert; Smith, Jason G. (2025). Mechanisms of AAV neutralization by human alpha-defensins.. PLoS pathogens, 21(7), e1013283. https://doi.org/10.1371/journal.ppat.1013283