Flashcards in Virology Deck (109):
What is virology?
the study of viruses and viral disease
What is a virologist?
someone who studies viruses
T or F: Viruses cause high rates of morality and morbidity in animals and birds?
T or F: Viruses cause financial loss to livestock and poultry industries
T or F: Some viruses are zoonotic ?
Are viruses non living?
What does a viruses contain?
nucleic aicd genome (DNA or RNA) surrounded by a protein coat (capsid) and in some cases a lipid envelope
T or F: Viruses posses standard cellular organelles?
False, THEY DONT
Can viruses make energy or proteins by themsleves?
T or F: Viruses are obligate intracellular parasites?
true, they hack the cell machinery
Do viruses have the capability to multiply by division?
How does a viruses reproduce?
by an assembly line in which various parts come together from different parts of the host cell to form new virus particles
What is a capsid?
protein shell of a virus that encases/envelopes the viral nucleic acid or genome
What is a capsid made up of?
capsomeres held together by non covalent bonds
What is nucleocapsid?
capsid + virus nucleic acid
T or F: some viruses have additional layer known as envelope
What is a envelope of a viruses made up of?
lipid bilayer derived from host cell
T or F: Glycoproteins are present on the surface of the envelope, and often appear as spikes
T or F: Naked viruses have only protein capsid enclosing nucleic acid?
T or F: Enveloped viruses have an additional lipid layer enclosing the protein capsid enclosing nucleic acid?
What is pleomorphism?
the ability of some viruses to alter their shape of size
Does RNA have double-stranded and single stranded RNA
Does DNA have double-stranded and single stranded DNA
What is virus replication?
attachment, penetration, uncoating, release in large numbers, assembly and maturation and synthesis of viral nucleic acid and protein
How are viruses classified?
the international committee on taxonomy of viruses
How are virsues transmitted?
direct contact, indirect, and common vehicle transmission
What is common vehicle transmission?
food borne or feces borne
What is vertical transmission?
infection that is transferred from mother to embryo, newborn
How does one diagnose viruses?
gross evaluation and histopathology
How do you detect viruses?
cultivation and isolation on tissue culture or inoculation in eggs
What is serology of viruses?
ELISA, viral antigen to host antibody, florescent antibody staining and immunohistochemical staining
What is RT-PCR
Reverse transcription polymerase chain reaction
How does one treat viral infections?
antiviral drugs, immune system stimulation
How does one prevent viral infections?
vaccinations, live attenuated, non-replicating, recombinant DNA, disinfectants and hygiene
What is an all in, all out management system?
animal houses are emptied, cleaned and disinfected between batches of animals
What is culling?
killing of animals to control viruses spread
What is pathogenicity?
the ability of a virus to cause disease in a host
What is pathogenesis?
manner of development of a disease
What is avirulent?
not harmful to the host
T or F: virulence is not an absolute property, but depends on many variables
What are factors related to a virus?
genetic variation, route of entry in host, affinity to host, dose of infection, immuno evasion
What are factors related to the host?
host species, host immunity, host physiological factors, fever
What are some other factors of virulence?
environment and dual infections
How does one measure a virus?
lethal dose 50: the dose of a virus required to cause death to 50% of animals
What is a route of entry for a virus?
skin, transcutaneous injection, mucous membranes, gastrointestinal tract, respiratory tract
What is viremia?
presence of virus in the blood
How does a virus spread into the bloodstream?
subepitheial tissue/ lymphatics and direct injection
What is secondary viremia?
virus has replicated in major organs and once more entered into circulation
What is a disseminated infection?
spreads beyond the primary site of infection
What is a systemic infection?
number of organs and tissues are infected
How does a viruses spread via nerves?
peripheral nerves, through receptor neurons, blood brain barrier
What is a nuerotropic virus?
viruses that can infect neural cells
What is tropism?
a affinity of a virus for a particular host tissue
What is a pantropic virus?
can replicate in more than one host organ/tissue
What is virus-cell interactions?
inhibition of host/cell nucleic acid or transcription
inhibition of protein synthesis
toxic viral infections
interference with cellular membrane function
T or F: cell lysis following virus replication allows release of new viruses?
What is apoptosis?
process of programmed cell death, cell suicide
What is an oncovirus?
What is a persistent infection of a virus?
not immediate death of a host cell, remain latent in host cell for long periods
T or F: Viruses cause immunosupression?
T or F: Shedding of infectious virons is crucial to the maintenance of infection in populations?
T or F: acute infections is intensive shedding over short periods of time?
T or F: persistent infections can shed at lower titers for months to years?
What are warts?
benign skin growths that appear when a virus infects the top layer of the skin
What is erythema?
reddening of the skin
What does a virus in the respiratory tract cause?
obstruction of air passages
hypoxia and respiratory distress
What does a virus in the central nervous system cause?
bursting (lytic) infections of neurons
killing of phagocytic cells
inflammatory cels around blood vessels
What is progressive demyelination?
canine distemper, damaged nerve, scarred myelin
What does damage to endothelium cause?
What is an teratogenic viruses?
cause developmental defects of embryo or fetus in utero infections
What is the latent period of infectious disease?
microbe is replicating but not yet enough for the host to be infectious
What is the incubation period of infectious disease?
microbe is replicating but host has no symptoms
What is communicable disease?
disease caused by agent capable of transmission by direct, airborne or indirect routes from infected person, animal or plant
What is a reservoir?
habitat in which infectious agent lives and grows
T or F: pathogens can escape immunity so that animals become susceptible again?
T or F: pathogens can evade immunity, allowing reinfection to occur after a short period of time
T or F: all sick animals are reservoirs?
What is vertical transmission of pathogens?
from host to its offspring, possibility through placenta or during parturition
What is horizontal transmission of pathogens?
from reservoir to new host
direct and indirect
What is a vehicle for pathogens?
inanimate object which serves to communicate disease
What is a vector?
a living organism that serves to communicate disease
What are fomites?
object that can be contaminated and transmit disease on a limited scale
What is a mechanical vector?
agent does not multiply or undergo part of its life cycle while in vector
What is a biological vector?
agent undergoes changes in vector
What are determinants of emergence?
type of agent
What is pathogenic adaption?
increased antibiotic resistance
What factors increase transmission of a pathogen?
increasing abundance of host
increasing pathogen prevalence
What is prevention of infectious disease?
inhibiting the introduction or establishment of a disease into an area, herd or individual
T or F: Rinderpest is only animal disease that has been eradicated?
What does eradication of a infectious disease involve?
complete elimination of the pathogen from a defined region
What is primary prevention?
avoid occurrence of disease by health promotion or specific protection
What is secondary prevention?
primary prevention failed
What is tertiary prevention?
both primary and secondary failed
What is farm biosecurity?
external ( leaving) and internal (spread)
all measures taken to minimize the risk of introduction and spread of agent
What is the purchasing policy?
closed herd system
reduce number of new animals
vaccination and health status of new animals
quarantine new animals
How does one remove infected individuals from a herd?
testing and slaughter
What is mass therapy?
eliminate pathogen from herd
What is biological control of an infection?
introducing a predator
What is the difference between isolation and quarantine?
isolation is ill with disease
quarantine is exposed to disease
What is chemoprophlaxis?
use of antimicrobal drugs
What are the four W's of immunization?
What are features of a safe vaccine?
safe to use
effective against different strains
few side effects
low in cost
benefit outwieghs risk
Where does the World Animal health publication come from?
world organization for animal health OIE
What are sentinel labs?
direct contact with patients
What is infected premises?
confirmed positive cases
infected zone surrounds this
What is contact premises?
may have been exposed to infection
What is a buffer zone?
surrounds infected zone
What is one health?
healthy people, healthy environment, healthy animals