Chap 13- Virus Types & Characteristics Flashcards
Viral infections cause win/loss of wars; worldwide devastation due to this particular virus in earlier centuries , ________
smallpox (devastation)
Virus & Christianity
Europeans who survived smallpox endemic brought the virus to the new world, killing droves of Aztecs while remaining untouched. Aztecs/new world inhabitants interpreted it as “Christian God” was dominant over their own
Seasonal influenza first described by who?
Hippocrates, described as winter illness “Perinthus”
Flu pandemics seemingly occur every ________.
Last flu pandemic before Rona was Spanish Flu of 1918 (affected 50mill, life expectancy dropped 12 yrs)
naturally occurring minor changes in influenza viruses due to mutation
antigenic drift (small changes result of mutation)
MAJOR changes where multiple strains of virus infect single host, and host can no longer recognize virus
antigenic shift (big changes due to multi attack on single host) (Ex: bird,pig, human flus mutating to one virus infecting single host)
any substance that causes the body to make an immune response against it
antigenic
Dmitri Ivanovsky was first to
isolate virus in tobacco plants & that the virus can pass through a filter. (sap from disease plants could transfer to healthy plants) (pores on filters too small for bacteria to pass, which led to discovery of viruses)
Shortcomings & doubts with Ivanovsky’s experiment?
He did not fulfill Koch’s postulates as he was unable to grow the virus from infected sap on culture. This caused doubt (maybe filters were broken? maybe it was just a toxin?)
Who proved Ivanovsky’s original findings?
M. Beijiernik showed SAP did not lose its disease ability despite after dilutions via multiple inoculations to healthy plants; dilution was not successful, so it cant be a toxin & it can replicate.
Virus Characteristics
needs living tissue spread, are obligatory intracellular parasites, contain DNA OR RNA , have protein coat, most only infect specific cell type
Virus in latin means
POISON
Are viruses ALIVE?
They are considered noncellular life/ acellular infectious agent
2 Things a Virus must have
Nucleic Acid (DNA or RNA - never both), Protein Coat
range of cells, tissues, etc that a virus can affect
host range
Viruses that infect Bacteria
Bacteriophages or “Phages”
How do most viruses connect to host cells?
via attachment sites (receptor sites on host cells)& cellular factor (outer surface of virus chemically connects to receptor sites on host cell)
Virus is generally these 3 shapes
icosahedral (20 flat triangles) , helical (capsomeres arranged in helix) , or complex (phage)
viral particle aka
VIRION
protein coat (of a virus)? made up of ? protects?
capsid; capsomeres; nucleic acid
Nucleic acid & capsid make the ____
Nucleocapsid
glycoprotein used for attachments to HOST cells (define the host range)
spikes
type of virus that HAS lipid enveloper; type of virus that DOES NOT HAVE lipid envelope
Enveloped Virus; Naked Virus (Non Enveloped)
outer lipid envelope derived from host’s plasma membrane that only SOME viruses have;
envelope
Suffix virus FAMILIES end in?
Viridiae
Genus end in “_____”
Virus (Ex: Enterovirus)
Name of disease virus causes; indicates regions/intensity
Species (Ex: Poliovirus) *Viruses usually go by Species name)
viruses who share ORAL TO FECAL route
enteric viruses
viruses who share RESPIRATORY/ SALIVARY ROUTE
respiratory viruses
viruses spread from animal to human & are literally the worse
ZOONOTIC viruses
viruses that spread via insects
arboviruses
Viral Genome Characteristics
VERY SMALL, only encodes its structural components (capsid proteins /enzymes) , which are only concerned about replicating its viral nucleic acids
How do virus multiply? (Generalized)
Firstly, must invade host cell. Once virus inside, it takes over host cell expression machinery. Now, the cell starts to produce viral components. These viral components are assembled and result in virus leaving cell and causing cell burst/death.
