Test 1 Deck 2 Flashcards
The ability of a virus to cause disease in a host is called
Pathogenicity
The mechanism of disease development is called
Pathogenesis
The degree of pathogenicity of a virus is called
Virulence
What 3 ways can you numerically measure virulence by using lab animals?
LD50
ID50
ID50 : LD50 ratio
LD = Lethal Dose
ID = Infectious Dose
The dose of the virus that kills 50% of animals is called
LD50
The dose of a virus that will *infect *50% of animals is called
ID50
What does a **low **ID50 and LD50 tell you?
A **low **ID50 and LD50 indicate a
**more virulent **organism
A **high **ID50 and LD50 tell you what about the organism?
A **high **ID50 and LD50 mean that the organism is
less virulent
What are the 4 routes of viral entry into a host?
Skin
Mucous Membrane
GI Tract
Respiratory Tract
What kind of antibodies are found in mucous membranes?
IgA antibodies
are found in mucous membranes
The *mucociliary blanket *is a defense of which portal of viral entry?
The *mucociliary blanket *is a defense of the
Respiratory Tract
What is the only portal of entry into a host that utilizes a **temperature gradient **as a defense?
Respiratory Tract
has a temperature gradient
How do viruses get to *subepithelial levels *?
Viruses can invade *subepithelial tissues *because
**inflammation **destroys epithelium
*or by using *
Transcytosis
An infection that spreads beyond the primary site of infection is called
A Disseminated Infection
Viruses can shed directionally from infected epithelium.
**Apical Release **of a virus facilitates what?
Apical Release
facilitates
Virus Dispersal
Viruses can shed directionally from infected epithelium
Basolateral Release
facilitates what?
Basolateral Release
facilitates
Systemic Spread
What is viremia?
Viremia is
the presence of a virus in the blood
If a virus is **free **in the blood, how long with the viremia last?
A **free **virus causes
Short-duration viremia
If a virus is **in a cell **like a lymphocyte in the blood, how long will the viremia last?
Viruses that are **in a cell **like a lymphocyte in the blood
cause
Prolonged Viremia
The initial entry of virus into blood is called
Primary Viremia
The viremia caused when a virus has replicated in major organs and once more entered circulation
is called
Secondary Viremia
This type of Viremia is caused by direct inoculation of virus into blood
Passive Viremia
List the types of Viremia from shortest time to longest time
Shortest time–>Longest time
Passive, Primary, Secondary
List the types of Viremia from low infectivity to high infectivity
Low infectivity –> High infectivity
Primary, Passive, Secondary
What type of viremia is characterized by
long time
and
high infectivity?
Secondary Viremia
A virus in blood interacts with macrophages
and creates a trojan horse.
What does this mean?
Trojan Horse
is when
trafficking monocytes transport the virus
How does the host clear viruses from the bloodstream?
The host clears viruses from the bloodstream by using
Mononuclear phagocytes
Antibodies
Complement System
Where are mononuclear phagocytes generated?
Mononuclear phagocytes are generated in the
Spleen, Liver, and Bone Marrow
and help to clear viruses from the blood
A virus that can infect neural cells is called
Neurotropic Virus
A virus that enters the CNS after infection of a peripheral site is called
Neuroinvasive Virus
A virus that **if **it enters the CNS, causes disease of neural tissue
leading to neurological symptoms and death
is called
Neurovirulent Virus
What are the 4 routes of Neural Spread of Viruses?
Axons
Perineural Lymphatics
Endoneural Space
Schwaan Cells
What type of neural spread travels the same direction of the nerve impulse from cell body to dendrite to axon?
Cell body –> Dendrite –> Axon
Anterograde Spread
What type of neural spread travels the *opposite *direction of nerve impulse flow from axon to dendrite to cell body?
Axon –> Dendrite –> Cell Body
Retrograde Spread
When a virus travels **towards **the brain and CNS, what kind of movement is it exhibiting?
**Towards **the brain and CNS
Centripetal Movement
A virus that travels **away from **the brain and CNS and to the periphery is exhibiting what type of movement?
**Away from **the brain and CNS
**Centrifugal **Movement
When viruses spread to the CNS via olfactory routes, what type of neural spread do they use?
Olfactory routes –> CNS
via
Anterograde spread
How do viruses get through the blood-brain barrier?
By secreting TNF
(To increase endothelial permeability)
By using MMP
(To breakdown endothelial cell junctions)
By using a Trojan Horse
(Getting trafficked by monocytes)
What type of viral infection do you have if the virus sheds intensively for a short period of time?
Acute Infection
What kind of viral infection do you have if the virus sheds at
low titers for a long period of time?
Persistent Infection
The specificity and affinity of a virus for a particular host tissue is called
Tropism
What do you call viruses that can replicate in more than one host organ/ tissue?
Pantropic Viruses
can replicated in more than one host tissue
A bullseye red rash is pathognomonic for what disease?
Lyme Disease
This type of skin ailment is characterized by a sloughing off of necrotic tissue
Ulcers
A benign skin growth that appears when a virus infects the top layer of skin
Warts
A skin ailment with solid elevations, no fluid, and has sharp borders
Papules
The reddening of skin caused by a systemic viral infection is called
Erythema
Viral-Bacterial Synergism is exhibited in which portal of viral entry?
Respiratory tract
has Viral-Bacterial Synergism
What are 5 injuries sustained by viral transplacental infection ?
Teratogenesis
Cerebellar Hypoplasia
Arthrogryposis
Porencephaly
Congenital hydraencephaly
Are caused by viral transplacental infection
Susceptibility to teratogens ________ with fetal age
Susceptibility to teratogens decreases with fetal age
Persistent infections, PI Calves, and Immunotolerant calves are seen in transplacental infection of Bovine Viral Diarrhea (BVD) between __ to __ months.
When a cow fetus contracts BVD between
2 to 4 months
The calves will live, but have persistent infections, or be immunotolerant
If BVD is contracted while the fetus is between 5-9 months, what is the result?
Abortion or Deformities
How is tissue damage caused in virus-induced immunopathology?
Tissue damage is from hypersensitivity reactions
*Moon- Blindness *is an example of what type of disease in horses?
Moon-Blindness
is an
Autoimmune Disease
True or False
Latent, Chronic, and Slow Infections are all types of Persistent Infections
TRUE
What type of viral infection is only demonstrated when reactivation occurs (during periods of immunosuppression)?
Latent (Persistent) Infections
**Cold Sores **and **Infectious Bovine Rhinotracheitis **are examples of what type of viral infection?
Latent (Persistent) Infections
A viral infection with a prolonged incubation period is called
Slow (Persistent) Infection
Slow viral infections are progressive and lethal. What causes these types of infections and give an example.
**Prions **cause Bovine Spongiform Encephalopathy
What are cytocidal effects of viruses on host cells?
Lysis and Apoptosis
A non-cytocidal effect of a virus on a host cell is
Persistent Infection
Cell Transformation is an effect of a virus on a host cell that leads to what type of cell?
Tumor cells
Damage or morphological changes to host cells during virus replication is called
CPE or
Cytopathic Effect
Complete destruction of cells, subtotal destruction of cells, and focal destruction of cells are all forms of what?
All are forms of
CPE- Cytopathic Effect
Histologically, what do you see in cells undergoing Cytopathic Effect?
Cell Lysis
Cell Rounding
Cell Detachment (death)
Vacuolation of Cytoplasm
Inclusion Bodies
An inclusion body that is an accumulation of *viral components *called Negri bodies is produced by which virus?
Rabies
What virus causes Owl’s Eye inclusion bodies, the result of degenerative changes in cells?
**Herpes Virus **
causes Owl’s Eye inclusion bodies
Inclusion bodies composed of *crystalline aggregates of virions *is caused by what virus?
Adenovirus
causes
crystalline virion inclusion bodies
Herpes virus, Morbillivirus, and some Paramyxoviruses can cause the formation of this.
Syncytium
The fusion of **4 or more **plasma membranes to produce an enlarged cell with 4 or more nuclei is called _________ formation
Syncytium formation
True or False
Only naked viruses are capable of syncytium formation.
FALSE
Only *enveloped *viruses can form syncytium
Syncytia formation may be the only detectable CPE (cytopathic effect) in which kind of viruses?
Synctia formation may be the only detectable CPE in
Paramyxoviruses
What are 4 mechanisms employed by viruses to cause cell injury or death?
Inhibition of Host Cell:
Nucleic Acid Synthesis
RNA Transcription
Protein Synthesis
Cell Membrane Function
When viruses interfere with host cell membrane function, this promotes ________ formation
Syncytia/ Cell fusion
How is Apoptosis different from Lysis
Apoptosis is a last ditch effort to eliminate viral factories within the cell.
Lysis happens when the virions have already been made, and are released when the cell is lysed
Non-cytocidal changes in virus infected cells are often associated with persistent infections.
These changes mostly occur in
________ virus infections.
Non-cytocidal changes in virus infected cells are often associated with persistent infections.
These changes mostly occur in
RNA virus infections
What are the 2 Apoptotic Pathways?
Mitochondrial (Intrinsic) Pathway
and
Death Receptor (Extrinsic) Pathway
This apoptotic pathway is initiated when **TNF **and **Fas **membrane receptors are activated
Death Receptor (Extrinsic) Pathway
**Perforin **and **granzyme **are used in which apoptotic pathway?
Death Receptor (Extrinsic) Pathway
Antibody dependent cell mediated cytotoxicity is something only ______ viruses can do.
Enveloped
An enveloped virus can fuse to the surface of a host cell which causes cross-linking. This cross-linking tells NK cells to kill the host cell by APOPTOSIS.
Essentially, the host cell has become the target of its own immune system.
Name this mechanism of virus-induced cell death
Antibody Dependent Cell Mediated Cytotoxicity
What is neoplasia?
Abnormal tissue overgrowth
The study of neoplasms and neoplasia is called
Oncology
Neoplasms (tumors) are derived from what?
A single genetically altered progenitor cell
What are the steps of the Cell Cycle?
G1
S
G2
M
Growth and DNA replication happen in what phase of the cell cycle?
S phase
Encoded proteins that function for *regular *cell growth and differentiation are known as
Proto-oncogenes