title: Precise improvement of ISAF reconstruction algorithm based on the computational radius of density function.
abstract: The output of icosahedral symmetry-adapted functions (ISAF) reconstruction algorithm is a virus capsid, where the density function of every outside point is theoretically zero. However, original ISAF algorithm takes reconstructed map as a solid sphere and density function of every point in the whole sphere is calculated. The density functions outside virus capsid may not be always zero, which may sometimes produce noise. In this study, Fourier shell correlation (FSC) is used for proving that density function calculation of original ISAF algorithm can reduce reconstruction precision. Subsequently, the range of virus capsid is determined with radial density function curve and the original ISAF algorithm is improved by calculating density function inside virus capsid. The experimental results on Cryo-electron microscopy (Cryo-EM) data of cytoplasmic polyhedrosis virus (CPV) indicate that the improved ISAF algorithm can generate more details of virus capsid and achieve a higher resolution.
authors.affiliation: Department of Information Art and Design, Academy of Art and Design, Tsinghua University, Haidian District, 100084, Beijing, China.
authors.forename: Gongming
authors.initials: G
authors.lastname: Wang
authors.affiliation: Institute of Computing Technology, Chinese Academy of Science, Haidian District, 100190, Beijing, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Xu
mesh_terms: D000465:Algorithms; D002213:Capsid / Q000648:ultrastructure*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008854:Microscopy, Electron / Q000379:methods*; D012087:Reoviridae / Q000648:ultrastructure*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Fourier shell correlation; Single-particle reconstruction; density function; icosahedral symmetry-adapted functions; virus capsid