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45 Cards in this Set
- Front
- Back
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Virus |
An infective agent Usually consists of nucleic acid in a protein coat Can only be seen with an electron microscope Have to have a host to multiply |
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Virion |
Complete, fully developed, infectious particle composed of nucleic acts and surrounded by a protein coat |
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Virology |
Study of viruses |
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Pandemic |
Prevalent over a whole country or the world |
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Virus characteristics |
-Acellular -Obligate intracellular parasites -Multiply inside living cells by using the synthesizing machinery of the cell -Lack ribosome and have few, if any, of their own enzymes -Contain DNA or RNA (not both) -Contain a protein coat (some enclosed by envelope) |
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Virus versus bacteria |
Virus - no cells, not alive, smallest, no metabolism, DNA or RNA Bacteria - has cells, alive, bigger than viruses, has metabolism, DNA |
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Louis pasteur contribution to virus discovery |
Coined the term virus Developed the first rabbies vaccine |
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Iwanowski and Beijernick contribution to virus discovery |
Discovered the first virus (Tobacco mosaic virus) Showed filtered extracts from diseased plants was a contagious fluid Beginning or virology |
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Loeffler and Frosch contribution to virus discovery |
Discovered foot and mouth disease in cattle |
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Nucleic acid function/characteristics |
DNA or RNA Single or double stranded Circular or linear Genetic material |
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Capsid function/characteristics |
Protein shell Made of capsomeres Protects genetic material |
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Capsomere function/characteristics |
Protein subunits that make up capsid Arrangement is characteristic to particular viruses |
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Naked virus function/characteristics |
No envelope Enters cell by endocytosis |
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Envelope function/characteristics |
Lipid substance that surrounds capsid Enters cell by fusing with body cell envelope |
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Spikes function/characteristics |
Carbohydrate-protein complex Project from envelope Help virus ahere to host Used in identification of some viruses |
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Morphology of polymerase virus and example |
Capsid is a polymerase (20 triangular faces and 12 corners) Capsomeres of each face form an equilateral triangle Adenovirus, Poliovirus |
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Morphology of enveloped virus and example |
Roughly spherical Influenza, herpes simplex, covid 19 |
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Morphology of helical virus and example |
Resemble long rods Nucleic acid is found within a hollow, cylindrical capsid Rabies, Ebola, tobacco mosaic virus |
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Morphology of complex virus |
Complicated structures Polymerase capsid and helical tail sheath Bacteriophage, poxvirus |
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Host range |
The spectrum of host cells a virus can infect Determined by specific host attachment sites and cellular factors Virus must chemically react with hosts receptor sites on cell membrane |
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Bacteriophage |
Viruses that infected bacteria and use them as host |
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Plaque method |
Growing bacteriophage in a suspension of bacteria 1. Add bacteriophage in suspension of bacteria 2. Mix and pour into petri dish 3. Incubate at 37 °C for 48 hours |
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Bacteriophage multiplication |
Multiply by 2 mechanisms Lytic cycle (ends with cell lysis/death of host cell) Lysogenic cycle (allows host to remain alive) |
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Lytic cycle steps |
Attachment (adsorption) Penetration Biosynthesis Maturation Release |
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Lysogenic cycle steps |
Attachment Penetration Integration (into bacterial chromosome by recombination forming a prophage) Most prophage genes are repressed and it becomes latent Bacterial cell replicated with prophage DNA |
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Prophage |
When phage DNA integrates within the bacterial chromosome by recombination |
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Structure and function if T even bacteriophage parts: capsid, contractile sheath, tail fibers, tail pins |
Capsid - stores nucleic acid Contractile sheath - used to penetrate/inject nucleic acid Tail fibers - attachment to host cell Tail pins - penetration |
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Animal virus multiplication steps |
Attachment Penetration Uncoating Synthesis Assembly Release |
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Bacteriophage versus animal virus multiplication |
Bacteriophage - has lytic and lysogenic cycles, no uncoating, tail fibers for attachment, only nucleic acid into cell Animal virus - like the lytic cycle with the addition of uncoating step between penetration and synthesis, whole virus into cell |
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Animal viruses grown in a lab |
Living animals - used to study immune response to the virus Embryonated eggs - easy and cheap. Viral growth is determined by death/damage to the embryo (used to make vaccines) Cell culture - continuous cell lines can be maintained indefinitely |
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Virus identification |
Cytopathic effects - damage to host cells Serological tests - detect antibodies against viruses in a patient Nucleic acids - uses PCR (amplifies nucleic acids) to obtain enough nucleic acids to identify virus |
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Virus taxonomy |
Generally described by a descriptive common name (no domain or kingdom) 134 families of viruses Family name ends in -viridae Genus name ends in -virus Species name is common name and any common numbers |
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Illness caused by adenoviridae |
Common cold |
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Illness caused by poxviridae |
Small pox Cowpox |
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Illness caused by orthomyxoviridae |
Influenza virus A, B, C |
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Illness caused by herpesviridae |
Cold sores Chickenpox Mononucleosis |
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Illness caused by papovaviridae |
Genital warts that can lead to cervical cancer (oncovirus) |
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Illness caused by retroviridae |
HIV COVID-19 |
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Illness caused by zika virus |
Microcephaly |
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Illness caused by ebola virus |
Fever Hemorrhaging Blood clotting Death |
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Illness caused by coronavirus |
Covid 19 |
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Latent viral infection and example |
Virus remain asymptomatic in host cell for long periods without causing disease Herpes simplex virus, varicella zoster virus |
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Persistent viral infection |
Occurs over long period and typically is fatal (chronic infection) Human papillomavirus, HIV 1 and 2 |
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How to prevent viral infection |
Vaccines, viricides, antiviral drugs |
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Prion |
Proteinaceous infectios particles (proteins) Inhereted/transmisible by ingestion, transplant, surgical instruments Cause neurological disease (Transmisible spongiform encephalopathies (TSE's) are large vacuoles developed in the brain |
