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49 Cards in this Set
- Front
- Back
smallest virus of 17 nm in diameter |
porcine circovirus |
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virus 18-28 nm in diameter |
parvoviruses |
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2 largest viruses |
pandora virus and pox virus |
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a complete virus particle that consists of an RNA or DNA core with a protein coat sometimes with external envelopes and that is the extracellular infective form of a virus |
virion |
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term used to describe any aspect of the infectious agent and includes: the infectious or inactivated virus particle, or viral nucleic acid and protein in the infected cell |
virus |
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an infectious particle smaller than any of the known viruses, an agent of certain plant diseases. the particle consists only of an extremely small circular RNA molecule, lacking the protein coat of a virus |
Viroid |
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3 important reasons to study vet. virology |
cause high rates of mortality and morbidity; tremendous financial losses (hampering economic development); some are zoonotic |
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method first used to immunize an individual against small pox with the material taken from a patient or a recently variolated individual in the hope that a mild but protective infection would result |
variolation or inoculation |
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derived the term vaccination by inoculating "cowpox matter" into the arms of healthy 8 year old boys |
Edward Jenner |
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injected dried, potassium hydroxide treated, infected rabbit brain material into 2 boys bitten by rabid dogs and both recovered |
Louis Pasteur |
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tobacco mosaic virus was the first virus to be: |
crystalized (1935) |
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2 individuals responsible for crystalizing TMV |
Ivanovski and Beijerinck |
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lipid bilayer with embedded proteins |
envelope |
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on surface of envelope and serve to identify and bind to host cell surface and are also significant to host immunity |
glycoproteins |
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the ability of some virus to alter their shape or size |
Pleomorphism |
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viral DNA that is complementary to mRNA and thus must be converted to positive sense RNA by an RNA polymerase before translation |
(-) sense viral RNA |
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viral RNA that is similar to mRNA and thus can be immediatly translated by the host cell |
(+) viral RNA |
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hydrolytic enzymes produced by bacteriophages to cleave the host's cell wall |
lysins |
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enzyme produced by a retrovirus that enables its genetic material to be integrated into the DNA of the infected cell |
Retroviral integrase |
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enzyme used to genrate complementary DNA from an RNA template |
reverse transcriptase |
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viral genome replication |
nucleic acid polymerase |
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enzymes that cleave glycosidic bonds, allows release of viruses from host cell |
neuraminidases |
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6 steps of virus replication |
attachment, penetration, uncoating, synthesis of viral nucleic acid/protein, assembly and maturation, release in large numbers |
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some viruses use more than one host cell receptor such as |
HIV |
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enveloped viruses can penetrate host cells via |
membrane fusion |
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enveloped and non-enveloped viruses can both penetrate host cells via: |
receptor mediated endocytosis |
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non-enveloped viruses can penetrate host cells via |
pore-mediated penetration of viral genome into host cell |
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once the viral genome has been released into the host cell, the virion can no longer be detected- known as: |
eclipse period |
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virus that begins to uncoat after binding to the external receptor but are not completely uncoated until inside the cell |
poliovirus |
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uncoating in some animal viruses requires a complex series of steps involving both host and viral gene products |
poxvirus |
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viruses in which the first stages of the viral replication cycle actually occur inside the capsid |
retroviruses and reoviruses |
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capsid and other proteins are synthesized in host cell: |
cytoplasm |
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replicate in the cytoplasm of INFECTED CELLS |
pox viruses |
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viruses with large double-stranded DNA genome such as Herpesviridae replicate via |
a complex replication process (encode additional proteins) |
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most RNA viruses replicate entirely in the cytoplasm of infected cells, two exceptions are: |
orthomyxoviruses and retroviruses (where host cell nucleus is involved) |
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synthesis of viral proteins from viral genomic RNA |
+ strand viruses |
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+sense viral RNA - cDNA- integrated into host cell chromosome; host cell then treats viral DNA as part of its own genome, translating and transcribing the viral genes |
Reverse Transcriptase |
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3 places in which virus assembly takes place |
nucleus, cytoplasm, plasma membrane |
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viruses are released from host cell by either: 2 |
lysis or exocytosis |
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4 things can result in the host cell upon release of the virus: |
cell death, no apparent changes, fusion of cells, transformation of cell to malignant one |
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Anitgenic drift in viruses causes 3 things: |
most cases minor changes, virus may become resistant to antiviral drugs, may cause change in antigenicity (detrimental effect on efficacy of vaccines) |
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virus that caused severe economic loss in the USA |
Porcine Epidemic Diarrhea Virus |
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the epidemology of viruses studied by using 4 steps: |
collection of sample, amplification, sequencing, analysis of viral genomes |
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contaminated inanimate objects called fomites are an example of: |
indirect contact transmission |
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the constant presence of a viral disease within a given geographic area of population |
enzootic viral diseases (endemic in humans)-- 2 examples are Dengue Virus and Louping 3 |
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the occurrence of more cases of viral diseases than expected in a given area or among a specific group of people/aniamls over a particular period of time. refers to peaks in disease incidence that exceed the endemic/enzootic baseline or expected incidence of disease |
epizootic viral diseases |
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a virus epidemic occuring over a very wide area and usually affecting a large proportion of the population |
panzootic viral diseases |
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epidemiology of viruses is complex and influenced by 5 factors: |
pathogen characteristics, host characteristics, environmental changes, vector characteristics, progress in science and technology |
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adult worms do not multiply in the definitive host. worms die over time, unless the host is re-exposed |
helminths (the severity of disease is proportional to worm load introduced into host!) |