Intro & Viral Pathogenesis I (Exam 1) Flashcards
Viruses gain new _________ so that they cause outbreaks in those new hosts.
host ranges
What occurs in viruses for them to result in infection and disease in new host species?
gene mutation
Viral mutations which cause infection of a new cell type, a different effect on cells, or increased viral replication can lead to an increased ________ of disease in the host.
severity
Many viral mutations do not cause dramatic changes in disease or host range, but instead result in _________.
antigenic drift
Mutation of viral genes for surface proteins is called:
antigenic drift
Viruses hijack cell processes for what purpose?
replication
Term for the vehicle for transmission of a virus.
virions
The structure of viruses includes a _______ core and an outer shell of viral proteins that is heat and drying resistant called _________.
nucleic acid
capsid
(T/F) Viruses can be DNA or RNA viruses.
True
A positive PCR test for FIP will indicate that the disease is present in that patient.
False - immunocytochemistry is best test
List the 3 groups of animal viruses.
DNA viruses
RNA viruses
RT viruses (reverse transcribing)
(T/F) All viruses have an envelope.
False
The process by which the envelope is acquired from the host cell membrane is called:
budding
(T/F) Viruses with an envelope survive longer in the environment than non-enveloped viruses.
False - opposite
Non-enveloped viruses are released from an infected cell via what process?
lysis
Nuclear or cytoplasmic aggregates of viral substances, usually capsid proteins, are called:
viral inclusion bodies
Viral inclusion bodies suggest what process?
viral multiplication
What 3 methods of entry to viruses use to get into a host cell?
membrane fusion
endocytosis
pore-mediated penetration
_________ is a method of viral entry when the cell membrane is punctured and connects with the unfolding viral envelope.
membrane fusion
Where do most DNA viruses replicate? What is the exception?
nucleus
exception: poxvirus (cytoplasm)
Where do most RNA viruses replicate? What is the exception?
cytoplasm
exception: retroviruses (nucleus)
Term for study of infection and spread of viruses and their mechanisms.
pathogenesis
Term for measure of a virus to produce disease.
virulence
(T/F) An animal can shed a virus without having the disease or clinical signs.
True
Birds are a common _______ for Equine Encephalitis Virus and West Nile Virus in horses as horses do not have high enough titers for transmission.
vector / reservoir host
Viruses are transferred by _________ or ________ transmission.
horizontal
vertical
For most viruses (horizontal/vertical) transmission is the most important route.
horizontal
Which type of viral transmission is from parents to offspring?
vertical
What are the 3 types of horizontal transmission of viruses?
- direct contact
- indirect contact
- vectors
While direct contact transmits viruses via cohabitating animals, indirect contact transmits them via contaminated ________ in the environment.
fomites
Through what 4 structures/tissues can viruses be transmitted vertically?
- germplasm
- egg
- placenta
- milk
What are the 3 major routes of viral transmission in veterinary medicine?
- respiratory
- oral
- fecal
List 2 ways a host defends itself against a virus transmitted via the respiratory tract.
- mucociliary clearance
- alveolar macrophage phagocytosis
________ are the main way that viruses are transmitted via the respiratory route.
aerosols
A host defends itself from a virus transmitted orally in what 3 ways?
- gut pH
- mucous
- peristaltic movements
Trauma and insect bites can transmit viruses via what route?
skin
List the 6 major routes of transmission by which viruses infect animals.
- respiratory
- oral
- fecal
- milk
- skin
- urogenital tract
A virus can be transmitted via placenta if what occurs in the pregnant female?
viremia (virus in bloodstream)
(T/F) If viremia occurs in a late-term gestation, the fetus will become infected and often abort.
False - immunity protects from infection
List the 5 mechanisms which viruses can use to cause disease.
- direct cell damage
- cell transformation
- inflammation
- immunosuppression
- immune-mediated disease
Immunosuppression caused by viruses can lead to ___________ infection.
secondary
A viral infection can be ________, all within the same organ system, or _________, resulting in viremia.
localized
systemic
Whether a viral infection is localized or systemic is determined by:
immune system response to virus
In a systemic infection, the virus will penetrate tissue and enter ________ will primary amplification occurs.
lymphatics
In systemic infection, after a virus enters the lymphatics, its progeny enter the bloodstream which is referred to as ___________.
primary viremia
After primary viremia in a systemic infection, the virus enters central organs of replication and undergoes replication leading to _________.
secondary viremia
After secondary viremia in a systemic infection, characteristic signs of disease are seen when what process is occurring?
viral shedding
(T/F) Clinical signs appear during primary viremia and secondary viremia.
False - only secondary
Why should you take diagnostic samples early for testing for viral infections?
shedding mostly complete once showing clinical signs
Recovery from viral infections occurs by depleting cell populations and the immune response. What type of immunity is most important in mediating recovery in active viral infections?
cell-mediated cytotoxic immunity
(Localized/Systemic) viral infections occur more rapidly.
localized
Term for study of frequency/distribution of viral diseases in a population, necessary for the control of viral spread.
epidemiology
The life cycle of a virus requires _______ to infect its next host.
excretion
Which virus example causes disease by direct cell damage, leading to organ dysfunction?
Canine Parvovirus
List two examples of viruses which cause disease by cell transformation, leading to either production or loss of function.
Bovine Leukemia Virus
FeLV
Bovine Leukemia Virus is an example of a virus causing disease via cell transformation. What main clinical sign develops?
lymphosarcoma
List 2 examples of viruses which cause disease via inflammation, and therefore, cell destruction.
Canine Distemper
FIP
List 2 viruses that cause disease via immunosuppression.
Canine Distemper
BVD
Give an example of a virus which causes an immune-mediated disease via antigen-antibody complex accumulation.
Equine Infectious Anemia
Canine Distemper is an example a virus which causes a (localized/systemic) disease.
systemic
