Biomedical Imaging

Computer Research And Technology

Investigators

Linked publications, trials & patents

Abstract

This project uses imaging science techniques to analyze many types of biological, clinical and biomedical images. Current research focuses on two general areas: (1) the structural biology of macromolecules using image processing of electron micrographs and NMR spectroscopy and (2) the development of sophisticated biomedical and laboratory imaging software. (1) The Imaging Sciences Laboratory has a major collaborative research effort with the Institutes involving the use of image processing techniques and advanced computational techniques in structural biology to analyze electron micrographs and NMR spectra with the goal of determining macromolecular structures. Recent efforts have concentrated on the 3D reconstruction, analysis and interpretation of the structures of icosahedral virus capsids. Ongoing research involves analyses of structures related to herpesvirus and papillomairus as well as other icosahedral virus capsids. Current papillomavirus vaccine trails utilize antibodies to the major capsid protein L1 of HPV-16. However, there are ~17 cancer causing HPV strains, and antibodies to each type of L1 are not cross-reactive against the other strains. We have been studying the structural biology of HPV-16 this year with three goals. First, we seek (in collaboration with NCI) to biochemically characterize and locate the minor capsid protein L2 as a possible vaccine candidate. Second, our production of HPV virions has produced a range of sizes for the particles from which a maturation study has been completed. Finally, using an L2 antibody from Johns Hopkins University which appears to be cross-reactive against more than one strain of HPV, we would like to locate how the AB binds to the virion, and locate the position of the epitope, amino acids 17-36. Careful biochemical analyses of HPV-16 demonstrates that there are ~36 copies of L2 in the virion. Cryo-EM and 3D difference imaging demonstrate that the bulk of the L2 is located under each capsomere (with 50% occupancy). The maturation studies demonstrate that the virion condenses in diameter as the capsid matures, with early procapsids being comprised of (almost) distinct capsomeres icosahedrally coordinated. As the procapsid shrinks, the floor of the capsid forms, and the capsomeres become more regular. Finally, preliminary analysis of the L2 MAb demonstrates that it bonds to the top-middle of each capsomere, indicating that some of the L2 is exposed to the outside environment in mature capsids, and that amino acids 17-36 are located near the surface of the capsid. We have also been developing computational tools for the study of the structure and dynamics of biological macromolecules using NMR data. We are actively supporting the intra- and extramural communities which use the Xplor-NIH biomolecular structure determination software package. Development of Xplor-NIH has continued in the following areas: (a) further progress in the use of the Python and TCL scripting interfaces and the addition of extensive documentation; (b) the backbone dynamics of two proteins have been studied using a new ensemble facility; (c) it is now possible to refine an ensemble of structures directly against order parameter and crystallographic temperature factor observables. (2) The Imaging Sciences Laboratory has a commitment to providing computational and engineering expertise to a variety of clinical and biomedical activities at NIH. Specifically, PET, ultrasound, CT, MRI, EPR, microscopy, imaging in cancer research, and imaging related to neural dysfunction have been supported in a number of ways. To support scientific in the NIH intramural program, CIT has developed and continues to enhance a sophisticated platform-independent, n-dimensional, extensible image processing and visualization application. The MIPAV (Medical Image Processing Analysis and Visualization) is an application that enables quantitative analysis and visualization of biomedical imaging modalities (from micro to macro) and is used by researchers at NIH and around the world. At NIH, MIPAV has used to analyze anatomical structures in CT datasets, assist in pretreatment analysis (registration and segmentation) of image datasets associated with radio frequency ablation (RFA) procedures, analysis of MRI datasets for NIMH, and has used by NCI for the analysis of 2D and 3D microscopic samples. In addition, we continue to support the NEI with age-related macular degeneration (AMD) and keratoconjunctivitis sicca (KCS) research.