Virus Imaging Core (Tom Hope, Director)
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The laboratory for the Virus Imaging Core is currently located on the third floor of the Tarry Building on the Chicago Campus of Northwestern University, and will relocate to the state-of-the-art Lurie Biomedical Research Building in the winter of 2008. The Hope laboratory currently houses 3 DeltaVision RT deconvolution microscopes. Importantly, these microscopes are in a biocontained room located close to our HIV culture facility, allowing the safe observation of infectious HIV. Deconvolution microscopy uses computer processing to compensate for distortion caused by the optical path. Through the observation of fluorescent beads, an algorithm is developed which corrects the distortion caused by lenses and removes out-of-focus light. The associated digital camera detects weak signals enabling great sensitivity and resolution, which is optimal for imaging viral particles in cells. Image capture with minimal illumination minimizes photobleaching and avoids phototoxicity, which can stress the cells during live cell observation. Two stand-alone workstations contain the complete Softworx software for deconvolutions and image processing, and off line image processing facilitates efficient instrument use. The systems are configured with filter sets allowing imaging of different types of fluorescent proteins including blue, cyan, green, yellow, and red fluorescent proteins. This permits simultaneous imaging of up to four different fluorescent proteins in live cells and 5 different fluors in fixed cell imaging. Importantly, two of these microscopes have environmental control chambers, including 5% CO2, allowing extended live cell timelapse microscopy. One of the microscopes with environmental control is equipped with a Photonics Mosaic digital diaphragm that allows precise sample illumination for photobleaching and photoactivation experiments. Additionally, this system has an ultrasensitive digital camera allowing maximal photon detection and signal amplification. A second microscope with environmental control has recently been updated with the latest Applied Precision imaging software and a high-speed EMCCD camera. Additionally, this microscope includes two zenon lamps with a multiplex imaging capabilities to allow live cell imaging in two colors simultaneously.
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Identifying Assembled Gag Complexes. Monoclonal antibody AG3 cannot recognize assembled or immature particles owing to epitope masking. Top: HeLa cell transfected with Gag-cherry and stained with AG3. Inset on right shows no green staining of VLPs. Bottom: Virus prepared with protease inhibitor cannot be stained with AG3 antibody. Images were taken in the Hope lab.
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