A faster way to make vaccines


Rebecca Pool

Tuesday, August 14, 2018 - 12:00
Cryo-EM image of polyclonal antibody/HIV envelope complexes at 4.7Å resolution, in a rabbit blood sample. [Hangartner, Ward labs, Scripps Research]
US-based researchers have developed an electron microscopy method to swiftly analyse the outcome of experimental vaccines against HIV and other pathogens.
The new system provides a nearly real-time picture of how anitbodies evolve and can be applied to any pathogen.
Using their set-up, Professor Lars Hangartner, Professor Andrew Ward and colleagues based at Scripps Research can quickly assess the full spectrum of antibodies produced in an individual in response to a pathogen or vaccine, and then determine if these antibodies are likely to be effective against the pathogen.
As part of their research, Hangartner and colleagues first purifed samples of rabbit blood, collected at different stages of an HIV vaccine trial, to break down the molecules and extract antibody fragments.
After mixing these antibody fragments with viral protein targets, they initially used negative stain electron microscopy - with a Tecnai Spirit microscope - to investigate how the immune system was developing its attack on the pathogen.
"After fine-tuning the biochemistry behind the formation of immune complexes of HIV Env trimers with antibody fragments, we were able to establish a very solid protocol allowing for semi-quantitative electron microscopy analysis," says Dr Matteo Bianchi, a former Scripps researcher now at the Institute of Medical Virology, University of Zurich.
"Never before have we been able to take a snapshot of our antibodies like this, giving us a more complete picture of what is happening and how we can influence the vaccination process," adds Hannah Turner, a research assistant in the Ward lab at Scripps. 
While the images were not high-resolution, the researchers were excited to report that this level of analysis - which only takes days - could become a routine test around the world.
"Most institutes have at least the technology and resources to do this level of analysis," says Ward.
For an even closer look at the antibodies, the researchers turned to cryo-EM, using a 200 KeV Talos Artica cryo-EM with a Gatan K2 Summit detector, to obtain high-resolution, 3D images of the antibodies with their viral targets.
The researchers were able to image polyclonal antibody/HIV envelope complexes at 4.7Å resolution, discovering that in rabbits, antibodies specific to vulnerable sites on HIV's outer glycan layer (see blue shapes on image) are structurally highly convergent and closely resemble a previously isolated monoclonal antibody 10A (green and teal ribbons).
Polyclonal antibody/HIV envelope complexes at 4.7Å resolution [Hangartner, Ward labs, Scripps Research].
The researchers believe these additional details may help scientists improve future experimental HIV vaccines and also hope their method will open the door to personalized design for vaccines.
"This method has the potential to change the pace at which we can develop vaccines," says Hangartner.
Research is published in Immunity. Read the open access paper here.
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