Silencing the Immunogenicity of AAV Vectors 

Recombinant adeno-associated viral (AAV) vectors are an appealing delivery strategy for in vivo gene therapy but face a formidable challenge: avoiding detection by an ever-watchful immune system (1,2). Efforts to compensate for the immune response to these virus particles have included immunosuppressive drugs and engineering the AAV vector to be especially potent to minimize its effective dosage. These methods, however, come with their own challenges and do not directly solve for the propensity of AAV vectors to induce immune responses.  

A recent study introduced a new approach to reduce the inherent immunogenicity of AAV vectors (2). Researchers strategically swapped out amino acids in the AAV capsid to remove the specific sequences recognized by T-cells that elicit the most pronounced immune response. As a result, they significantly reduced T-cell mediated immunogenicity and toxicity of the AAV vector without compromising its performance.  

Read on to get more of the study details, which include the use of NanoLuc® luciferase and Nano-Glo® Fluorofurimazine In Vivo Substrate for in vivo bioluminescent imaging of the AAV variants’ distribution and transduction efficiency in mice. 

A teal colored ribbon model of a AAV virus capsid floats against a black background.
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Glowing Testimonies: A Review of NanoLuc® Use in Model Organisms

NanoLuc®

Model organisms are essential tools in the pursuit of understanding biological processes, elucidating the mechanisms of diseases, and developing potential treatments and therapies. Use of these organisms in scientific research has paved the way for groundbreaking discoveries across various fields of biology. In particular, non-mammalian models can be valuable due to characteristics such as rapid life cycles, low cost, and amenability to use with advanced genetic tools, including bioluminescent reporters such as NanoLuc® Luciferase.

NanoLuc® is a small (19.1 kDa) luciferase enzyme originating from deep sea shrimp that is 100x brighter than firefly or Renilla luciferase. It utilizes a furimazine substrate to produce its bright glow-type luminescence. In the decade following its development, the NanoLuc® toolbox has expanded to include NanoBiT® complementation, NanoBRET™ energy transfer methods, and new reagents such as the Nano-Glo® Fluorofurimazine In Vivo Substrate (FFz) which was designed for in vivo detection of NanoLuc® Luciferase, NanoLuc® fusion proteins or reconstituted NanoBiT® Luciferase. In addition to the aqueous-soluble reagents increased substrate bioavailability in vivo, with fluorofurimazine, NanoLuc® and firefly luciferase can be used together in dual-luciferase molecular imaging studies.

Here we spotlight some recent research that demonstrates how the expanded NanoLuc® toolbox can be adapted to use in non-mammalian models, shedding new light on fundamental biological processes and advancing our understanding of complex mechanisms in these diverse organisms.

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Illuminating the Brain with a New Bioluminescence Imaging Substrate

Bioluminescence imaging is a powerful tool for non-invasive studies of the effect of treatments on cells and tissues. The luminescent signal is strong, and can be used in vivo, enabling repeated observations over time, allowing longitudinal study of cellular changes for hours or days. Bioluminescence imaging can be used in live animals over varying periods of time, without interfering with normal cellular processes.

Fluorescence imaging is also used in cellular studies. Although it can provide a stronger signal than luminescence, fluorescence requires light for excitation, and thus its in vivo use is limited at a tissue or cell depth greater than 1mm.

NanoLuc® Luciferase. Small, bright and now useful in brain bioluminescence imaging.

In addition, autofluorescence can be an issue with fluorescence imaging, as cellular components and surrounding proteins and cells can fluoresce when exposed to light. Autofluorescence can result in high background signals, making it difficult to distinguish true fluorescence from background.

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Seeing is Believing: How NanoLuc® Luciferase Illuminates Virus Infections

Artists interpretation of in vivo imaging of viral infections in mice using NanoLuc luciferase.

Wearing blue surgical gowns and white respirator hoods, research scientist Pradeep Uchil and post-doctoral fellow Irfan Ullah carry an anesthetized mouse to the lab’s imaging unit. Two days ago, the mouse was infected with a SARS-CoV-2 virus engineered to produce a bioluminescent protein. After an injection of a bioluminescence substrate, a blue glow starts to emanate from within the mouse’s nasal cavity and chest, visible to the imaging unit’s camera and Uchil’s eyes.

“We were never able to see this kind of signal with retrovirus infections.” Uchil is a research scientist at the Yale School of Medicine whose work focuses on the in vivo imaging of retroviral infections. Normally, the mouse would have to be sacrificed and “opened up” for viral bioluminescent signals from internal tissues to be imaged directly.

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World Firefly Day: Shining More Light on Glo-ing Innovations

On July 3rd and 4th, 2021, we celebrate World Firefly Day, and 2021, marks 30 years of luciferase products firefly luciferase vectors and Luciferase Assay System. These tools are key in advancing bioluminescent technology. To celebrate this day, we want to highlight some innovations that have been made possible with these tools.

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Understanding Inflammation: A Faster, Easier Way to Detect Cytokines in Cells

Inflammation, a process that was meant to defend our body from infection, has been found to contribute to a wide range of diseases, such as chronic inflammation, neurodegenerative disorders—and more recently, COVID-19. The development of new tools and methods to measure inflammation is crucial to help researchers understand these diseases.

This diagram shows how the Lumit™ Immuno assay can be used to detect cytokines.

Cytokines—small signaling molecules that regulate inflammation and immunity—have recently become the focus of inflammation research due to their role in causing severe COVID-19 symptoms. In these severe cases, the patient’s immune system responds to the infection with uncontrolled cytokine release and immune cell activation, called the “cytokine storm”. Although the cytokine storm can be treated using established drugs, more research is needed to understand what causes this severe immune response and why only some patients develop it.

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Celebrating 30 Years of “Glo-ing” Research

This post is written by guest blogger, Amy Landreman, PhD, Sr. Product Manger at Promega Corporation.

In December of 1990, Promega first discussed the use of firefly luciferase (luc) as an emerging reporter technology in the article, Firefly Luciferase: A New Tool for Molecular Biologists. At the time, the gene coding chloramphenicol acetyltransferase (cat)  was most commonly used by researchers, but it was thought that the bioluminescent properties of firefly luciferase, extreme sensitivity and rapid simple detection, could make a significant difference in how molecular biologists tackled their research. Several months later, the first firefly luciferase reporter vectors and detection reagents became available as products, making this new technology more broadly accessible to the research community. Today firefly luciferase is no longer a “new tool”, with it and many other bioluminescent reporter technologies being standard elements of the modern research toolbox.

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Bioluminescence and Biotechnology: Shining Nature’s Cool Light on Biology

Imagine you’re taking a refreshing night swim in the warm blue waters of Vieques in Puerto Rico. You splash into the surf and head out to some of the deeper waters of the bay, when what to your wondering eyes should appear, but blue streaks of light in water that once was clear. Do you need to get your eyes checked? Are you hallucinating? No! You’ve just happened upon a cluster of dinoflagellates, harmless bioluminescent microorganisms called plankton, that emit their glow when disturbed by movement. These dinoflagellates are known to inhabit waters throughout the world but are generally not present in large enough numbers to be noticed. There are only five ecosystems in the world where these special bioluminescent bays can be seen, and three of them are in Puerto Rico. 

Bioluminescent plankton exhibit a blue glow when disturbed.
Bioluminescent plankton in the ocean

But you don’t have to travel to Puerto Rico or swim with plankton to see bioluminescence. There are bioluminescent organisms all over the world in many unexpected places. There are bioluminescent mushrooms, bioluminescent sea creatures—both large and small (squid, jellyfish, and shrimp, in addition to the dinoflagellates)—and bioluminescent insects, to name a few. Bioluminescence is simply the ability of living things to produce light.

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Barking Up the Right Tree: Using NanoLuc to Screen for Canine Distemper Antivirals

Canine distemper virus (CDV) is a highly contagious pathogen that is the etiological agent responsible for canine distemper (CD), a systemic disease that affects a broad spectrum of both domestic dogs and wild carnivores. While there are commercially available vaccines for CDV that can provide immunity in vivo and protect canines from contracting CD, there is a strong demand for effective canine distemper antivirals to combat outbreaks. Such drugs remain unavailable to date, largely due to the laborious, time-consuming nature of methods traditionally used for high-throughput drug screening of anti-CDV drugs in vitro. In a recent study published in Frontiers in Veterinary Science, researchers demonstrated a new tool for rapid, high-throughput screening of anti-CDV drugs: a NanoLuc® luciferase-tagged CDV.

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New Bioluminescent Sensor Can Detect Multiple Antibodies in a Single Drop of Blood

nanoluc invivo imaging

Antibody tests are often used to determine whether individuals have been exposed to certain bacteria or viruses. For most existing antibody tests, the process goes something like this: A vial of blood is drawn from the individual, the vial is sent to a lab, then a trained technicians performs the antibody test and sends back the results. The current process is less than ideal for a few reasons. For one, blood draws are invasive and can be painful. Also, getting results could take days, due to the time required to deliver and process the sample. Lastly, costs can be high, since the need for trained professionals and specialized instruments in laboratory settings adds to the cost of each test.

What if all you needed to do for an antibody test was apply a single drop of blood onto a thin piece of film, and you would get results on the spot within five minutes? Scientists have recently developed an antibody test based on bioluminescent technology that could make this a reality. They describe their findings in a recent study published in ACS Sensors.

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