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79 Cards in this Set

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Description of a virus: ________________ surrounded by a ________________.
nucleic acid
protein coat
Viruses are __________________ __________________ parasites that use the host as an energy source
obligate intracellular
The smallest virus is ________________, 30nm in size.
Poliovirus
The largest virus is ___________ in size, 10 times larger than E.coli.
300nm
Viruses have a metabolic system. T/F
False
Viruses produce asexually. T/F
False
Viruses are not cells. T/F
True
Most viruses can only affect a limited number of cell types. T/F
True
Proteins encoded in viral genomes fall into three major categories:
i) enzymes required for replication of the genome and production of mRNA
ii) proteins used in the assembly of progeny virus
iii) larger viruses encode proteins that interfere with host defense mechanism
Which of the following do viruses not contain?
a) DNA
b) RNA
c) ATP
d) proteins
ATP
(most) viruses are haploid. T/F
True
Three broad classes of viruses are:
1. DNA genomes
2. RNA genomes
3. Viruses encoding a RT enzyme
DNA genome is replicated by:
direct DNA --> DNA copying
RNA genomes are replicated by:
direct RNA --> RNA copying.
Replication of the RNA genome requires:
viral replicase enzymes because cells do not process efficient RNA --> RNA copying enzymes
Virus nomenclature:
"orders" are named with the suffix ________________
virales
a virus suffix ending in "viridae" is under:
family
Virus names ending in "virus" is classified under:
genera
Parvoviridae
human parvovirus B19
Papovaviridae
human papilloma virus B19
Adenovaridae
colds
Herpesviridae
herpes simplex virus (HSV), Epstein-Barr virus (EBV)
Poxviridae
small pox, vaccinia
Hepadnaviridae
hepatitis B
Retroviridae
HIV, human T cell lymphotrophic virus
Orthomyxoviridae
influenza
togaviridae
rubella
Filoviridae
Ebola, Marburg
Picornaviridae
hepatitis A, poliovirus
paramyxoviridae
mumps, measles
Flaviviridae
hepatitis C, dengue fever
The capsid is make up of smaller subunits called:
capsomers
Two types of capsomer rearrangments are:
helical and icosahedral
complex viruses include: (2)
reovirus
baculovirus
poxvirus
the viral envelope is composed of a ___________ that oringates from _________________
lipid bilayer
host's membrane
two important glycoproteins of HIV include:
gp120
gp41
All RNA viruses (except retroviruses) encode an _____ - dependent ______ polymerase
RNA
RNA
Retroviruses contain an _____ - dependent ______ polymerase
RNA
DNA
Reassortment (exchange of genetic material between two segmeted genomes) is common in which strain of virus?
Influenza A
Three consequences of genetic changes (mutations) are:
-recognize a new host
-become drug resistant
-escape Ab recognition
tropism refers to:
the interaction of a viral attachent protein with a cellular receptor protein
3 processes that take place during the initiation step of viral replication are:
attachment
penetration
uncoating
3 processes that take place during the release phase of viral replication are:
assembly
maturation
release
Direct penetration is utilized by __________ viruses only. This mechanism results in only the _________________ entering the host cell and the capsid remaining _________________
naked viruses
genetic material
capsid
Fusion only occurs with _____________________. When this occurs, _______________ and ________________ enter the host cell.
enveloped viruses
capsid
genome
A mechanism in which both naked and enveloped are taken into the cell is called:
endocytosis
Uncoating is a process in which removal of the ________________ exposes __________________________
protein capsid
the genome to the inside of the host cell
What kind of virus can use their genome directly as mRNA
plus sense RNA viruses
In the maturation stage of viral replication, a common activity that takes place is ___________________________________________________________
the processing of protein precursors into teir final products through protease activity
list the three methods of release of virions:
1. budding
2. cell lysis
3. exocytosis
In budding, the virion distends through a membrane and in the process become ________________
enveloped
When a virion is released via budding, during exit the envelope is comprised of:
both viral and host proteins
cell lysis occurs when:
the cell becomes overwhelmed by the viral load
enveloped viruses are released into the cell by:
budding
exocytosis
naked virions are released from cells by:
lysis of the host cell
exocytosis
naked viruses can penetrate via:
direct entry/penetration
endocytosis
enveloped viruses can penetrate via:
fusion
endocytosis
what are the four types of viral infections?
abortic
lytic
persistant
slow
latent infections can be reactivated by:
stress, UV light, immunosuppression, fever, nerve injury
Antigenic variation refers to:
a virus changing or removing certain surface progteins so that antibodies made during previous infections will no longer recognize the virus
Molecular mimicry is:
a virus expressing a protein on its surface that is very similar to a host protein so antibodies "do not destroy them"
List four ways a virus employs mechanisms to avoid destruction by the host immune system
-molecular mimicry
-inhibiting antigen presentation
-antigenic variation
-entering privileged sites
Which two viruses can cause fetal death and abortion?
parvovirus and variola
Virulence is:
the capacity of a pathogen to infect and cause harm to a host cell
Shedding refers to:
release of a virus into the environmen
the most rapid and effective means for viral spread is through:
the bloodstream
the three responses that take place as a response to a viral infection are:
-destruction of infected cells
-the production of interferon
-neutralization of viruses
what are the components of innate (nonspecific) defense?
complement
NK cells
interferons
phagocytes (macrophages, neutrophils)
what are the components of adaptive (specific) defense?
B-cell activation, production of antibodies
T-cells
Cytotoxic T cells
Memory cells
The first line of defense against viruses are:
interferons
Interferons are virus nonspecific (T/F)
True
Three main types of IFNs are:
alpha, beta, gamma
IFNalpha and IFNbeta are secreted by:
cells that are infected with the virus
IFNgamma is released by _______________ and activated by:
NK cells
CD4 Th cells
Passive immunization if the adminstration of:
antibody
An example of natural passive immunity is:
mothers pasing immunoglobulins to the infant in serum or milk
Three important anti-viral immunoglobulins preparations are:
HBIg
VZIg
RIg
Active immunization is the admistration of a(n):
antigen
Immunization is an example of _______________, _______________ immunization
artificial, active