Virus Classification Flashcards
What is a capsid and its function?
Protein shell, can be composed of subunits called capsomers or an amorphous mix
Protects nucleic acid and important for attachmen of virus to cell surface receptors
What is a viral envelope and its function?
Membranous outer structure of some viruses, surrounds capsid
Protein spikes often involved in virus attachment and are important antigens
What is the classification of virus based on?
Structural and biochemical characteristics
NOT disease characteristics
What can the shape of a viral capsid be?
Icosahedral
Complkex
Helical
How many capsomeres does adenovirus have?
252
What characteristics of nucleic acid can be used to classify viruses?
Type - RNA or DNA
Strandedness - single or double
Segmentation - 1-10 segments
What is multiplicity of infection?
Number of infectious virus particles added per cell to initiate infection
What are permissive cells?
Support replication to produce progeny virus
What are nonpermissive cells?
Lack essential factors for complete viral replication, may be transformed by certain tumor viruses
What are cytopathic effects?
Effects due to virus infection
Rapid destruction (lysis)
Slow cell death with continuous virus release
Enhanced cell proliferation
Cell maintenance in persistently infected or latently infected cells
What is a virus assay?
Quantifies infectious virus particles
Cytolytic viruses can form plaques under agar, 1 plaque = one infectious particle
What is a FOCI?
Proliferation of transformed cells in localized ares of a cell monolayer
Cells transformed by viruses
What viral assay detects infectious and noninfectious virus particles?
Hemagglutination - virus-erythrocyte lattice formation
Virus protein hemagglutinin binds to receptors on RBCs
