Flashcards in MIP: Introduction to Virology Deck (36):
What does it mean that viruses are obligate intracellular parasites?
Viruses require intracellular environments, and often intracellular machinery to replicate
What was the first human virus to be identified?
What are the basic structural components of a virus?
Nucleic acids, a protein shell/capsid, and sometimes an envelope
What are the 7 viral genome types?
ds DNA, ss DNA, ds RNA, ss + RNA, ss - RNA, ss + RNA to DNA, ds DNA w/ RNA intermediate
What information is contained in the viral genome?
The information necessary to initiate and complete an infectious cycle
What is a viral capsid and what is its function?
A protein coat surrounding the genome that maintain the virus and protects the nucleic acids
What is a capsomer? A protomer?
Capsomers are the repeating protein subunits that make up the capsid and Protomers are the polypeptide chains which make up capsomers
What are the simplest structures that can be built as a capsid?
Helical and icosahedral capsids
What is a virion?
The complete virus particle
What is a nucleocapsid? Nucleoprotein?
Nucleocapsids are capsid proteins assc. w/ viral genome; Nucleoproteins are proteins assc. w/ the viral genome that aren't part of the capsid
What is the difference between enveloped and naked viruses?
Enveloped viruses have capsids that are covered by host cell membrane
How do viruses attach to their envelope?
Viral encoded protein "spikes"
How are viruses classified? What is the most consistent classification based on?
Disease, mode of transmission, structure, and biochemical characteristics (latter 2 most consistent)
What are the main characteristics of viruses that classifications are based on?
Type of genome, capsid symmetry, presence/absence of envelope, and size of genome and capsid
What is a bacteriophage?
A virus that infects bacteria
What is a viroid?
Infectious agents that consist solely of short strands of circular, ss RNA w/o a protein coat
What is a prion?
An infectious agent comprised only of proteins w/o nucleic acids
Where are prion proteins most abundantly found in the body?
What are the most well-known human prion diseases?
Creutzfeldt-Jakob Disease (CJD), variant CJD, Gerstmann-Stausler-Scheinker Syndrome, Fatal Familial Insomnia, and Kuru
What is the basis of Creutzfeldt-Jakob disease? What is the biggest risk factor?
Spontaneous transformation of normal proteins into prion proteins which allows for plaque formation; improperly sterilized surgical instruments
What are the different events of the viral life cycle?
Attachment, Entry, Release of genome (uncoating), genomic replication, creation of new virus, release from cell
How do viruses attach to cells?
Nonspecific electrostatic interactions as well as specific interactions with cell membrane proteins
What are the two major mechanisms of viral entry into cells?
Non-endocytic route (enveloped viruses fuses with cellular membrane) and the endocytic route (clathrin-mediated endocytosis)
What are the general differences between the replication of RNA and DNA viruses?
RNA viral replication occurs in the cell cytoplasm using virally encoded RNA-dependent RNA polymerase; DNA viral replication occurs in the nucleus and uses cell machinery
True or False: Host cellular machinery is needed for viral assembly.
What are the possible modes of transmission for viruses?
Blood, fecal-oral, respiratory, arthropod/zoonotic, mother to infant, urogenital, sexual contact, direct contact
What is the difference between a localized and disseminated infection?
Localized infections have the same entry point and area of effect; disseminated viral infections may gain entry at one location but affect another
What is viremia?
Presence of virus in the blood
What are common characteristics shared by viruses transmitted via a fecal-oral route?
All naked viruses that are generally very resilient
What are viral quasispecies?
A heterogeneous group of sequences clustering around a consensus
What are zoonoses?
Virus introduced into new populations via animal or arthropod vector
What is our best tool for controlling viral infections?
What is viral virulence?
A quantitative statement of the degree or extent of pathogenesis (capacity of virus to cause disease in an infected host)
What are the major mechanisms of viral pathogenesis?
Lytic infections kill the cell, and persistent infections do not cause cell death and may be chronic, latent, recurrent, or transforming
What is syncytia?
Fusion of cells resulting in a large mass of cytoplasm containing several nuclei and is amechanism of viral cytopathogenesis