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Investigating lentivirus titer with macro mass photometry 

Lentivirus production requires efficient analytical techniques 


Lentiviral vectors are one of the most frequently used delivery systems in cell and gene therapy. The development and production of lentiviral vectors requires accurate sample characterization. Physical and infectious titers, in particular, need to be characterized, as they affect the efficacy, dosing and transduction efficiency of lentiviral vectors. However, current analytical techniques for measuring physical titer are either informative but time-consuming, or fast but inaccurate. Characterizing infectious titer, on the other hand, takes days. As a result, sample characterization remains a challenge in lentivirus development and production

Schematic structure of a loaded lentiviral vector.

Fast, accurate lentiviral vector characterization with macro mass photometry 


Macro mass photometry is a powerful technology that addresses the analytical bottleneck in lentivirus development and production. It characterizes samples by measuring two parameters for each single particle: Contrast – a qualitative parameter correlated with the particle’s composition and mass – and size. Measuring these two parameters allows macro mass photometry to characterize different populations in samples with high heterogeneity, and makes it suitable for the analysis of both crude and purified samples during lentivirus purification.


The KaritroMP – Refeyn’s macro mass photometry instrument – provides detailed information in a matter of minutes, consuming little sample. Combined with its small instrument footprint, these strengths make the KaritroMP ideal for in-process, in-house sample analysis during lentiviral vector development and production.  

A typical macro mass photometry measurement, comparing crude and purified LVV samples

Macro mass photometry measurements correlate with lentivirus titer 

By measuring both contrast and size at the single-particle level, the KaritroMP macro mass photometer can identify different populations within a sample. Within these populations, the range of contrast-size values that correspond to lentiviral vectors can be identified. For each sample, the percentage of particles that fall within this range correlates with the physical titer of the sample. This percentage also correlates with the functional titer, although macro mass photometry is not sensitive to infectivity directly. These measurements are helpful to assess success throughout lentivirus production and purification workflows.

Macro mass photometry supports lentiviral vector analytics 

A blurred sample of the application note

In this application note, you will see how macro mass photometry can measure crude and purified lentiviral vector samples, characterizing complex samples in a matter of minutes. You will also find data from the KaritroMP macro mass photometer demonstrating that macro mass photometry measurements correlate with both physical and functional titer.   

Additional resources​


Characterizing large viral vectors using macro mass photometry

Accurate characterization of large viral vectors is a critical step in the development of viral vector-based gene therapies and vaccines. This webinar presents case studies and benchmark results on how the KaritroMP employs macro mass photometry to facilitate fast, straightforward, and qualitative analysis of single viral particles in cell and gene therapy applications. It also shows that it is well-suited for comparing different production and purification methods, as well as assessing batch-to-batch variations – ensuring the safety and efficacy of pharmaceutical products brought to market. 

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Macro mass photometry.png

Macro mass photometry: A new way to characterize large viral vectors


Macro mass photometry is a revolutionary new technology for analyzing large viral vectors, such as adenoviruses (AdV) and lentiviruses (LVV). Returning results in minutes, it offers fast, simple, qualitative analysis to inform process development and optimization in the development of cell and gene therapies and vaccines.  Here, you can learn the basic principles of macro mass photometry and its applications. 

For more information on analyzing viral vectors with macro mass photometry 

More Application Notes

Browse through our catalogue of application notes highlighting some recent case studies featuring mass photometry.

Investigating lentivirus titer with macro mass photometry


Mass photometry supports membrane protein purification protocols 

Characterizing protein oligomerization with automated mass photometry

Quantifying heterogeneous AAV capsid loading using mass photometry

Download the application note

Investigating lentivirus titer with macro mass photometry
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