How material analysis can help unlock a new era for gene therapy
Techniques like MADLS and SEC are helping researchers develop more effective viral vectors
Have you ever heard the saying ‘when life gives you lemons, make lemonade’? It’s a phrase that applies quite well to one unlikely hero of biotechnology: viruses. And particularly when it comes to gene therapy.
By introducing new genetic material into cells to repair or replace mutated genes, gene therapy has the potential to treat the diseases that these genes cause. But for it to work, we need vectors: a way to get this new genetic material inside the body. That’s where viruses come in – because if there’s one thing they’re good at, it’s getting DNA into cells.
Of course, normally this isn’t the kind of DNA that we want! But, if this damaging DNA is replaced with the right genes, great possibilities for new gene therapies open up. And among the viral vectors that could be used for gene therapy, recombinant Adeno-Associated Viruses (rAAVs) are particularly promising. Why? Because, uniquely, they don’t cause any detectable illness.
The great characterization challenge
So, it’s no surprise that many researchers are developing viral vectors based on rAAVs. But there’s been one significant roadblock: the lack of accurate, rapid, and reliable ways to characterize and quantify the rAAVs’ viral concentration. To develop efficient rAAV therapies cost-effectively, researchers need to optimize production yields, the design of the virus’ protein shell (or capsid), and processes and formulation conditions. Plus, of course, deliver robust quality control!
To do this, researchers need to be able to characterize their rAAV samples at different stages of the process. Not just for viral concentration, but also for capsid count and charge, particle size, aggregate formation, stability, full-empty ratio, and genome release… the list goes on! All this often requires multiple technologies. And unfortunately, the typical methods available – including ELISA, ddPCR, AUC, and EM – can be time-consuming, labor-intensive, and have limited accuracy.
MADLS and SEC: All-round analysis in just a few minutes
Luckily, dynamic light scattering (DLS) can provide a solution to these challenges. DLS can be used to measure particle size distribution of virus population during production, to separate good and stable samples from those with contaminants or aggregates during screening. Multi-angle dynamic light scattering (MADLS) goes one step further, enabling rapid rAAV screening with higher resolution than traditional single-angle DLS systems.
What’s more, with the new MADLS-based particle concentration measurement available on Malvern Panalytical’s Zetasizer Ultra, it’s now possible to analyze particle size and size distribution together, along with particle concentration per population. And all in just a few minutes! Together with multi-detection size exclusion chromatography (SEC) systems such as OMNISEC, this makes it easier for researchers to determine the key characteristics of their rAAV samples.
Performance that holds up in practice
But how well do these solutions work in real-world applications? We decided to find out through a couple of tests! In one, we used both the Zetasizer Ultra and OMNISEC to analyze viral concentration and full-capsid content in rAAV samples at different levels of genome loading and sample heterogeneity. Another test was done by Allergan, using three different AAV samples and comparing results to those from capsid ELISA-based virus concentration assays.
Both tests found that the Zetasizer Ultra provided rapid, accurate, and robust quantitative measurements of viral titer and full capsid content. Plus, when used in combination with OMNISEC, we could also report on factors such as aggregate content, fragment content, and thermal stability without needing AAV calibration standards, extensive method development, or dedicated reagents.
From easier rAAV analysis to more effective gene therapies
In short, MADLS and multi-detection SEC offer simple, reliable ways to analyze rAAVs, with fewer external factors influencing the results. In this way, they’re helping biotechnology researchers to turn these tiny viruses into big breakthroughs for gene therapy.
Keen to learn more? Check out the full details in our application note!