Introduction to virology
What are viruses ?
Most abundant biological entities on the planet
They need a living host to replicate
RNA or DNA that’s package in protein, some viruses have lipids
Major roles in global ecology and evolution of the biosphere
Obligate intracellular parasites that package their genomes into tiny protein/lipid particles
All organisms on the planet harbour distinctive repertoires of viruses
We breathe and eat billions of virus particles
Human DNA consists partly of ancestral viral genetic material
Number of viruses on earth: >10^16 HIV particles on Earth
More viruses in a liter of sea water than people on earth
Viruses are everywhere: plants, water, animals, food
The human microbiome = diversity of bacteria that we carry in our bodies
The human virome = viruses that live on bacteria/that feed on bacteria
-> determining which viruses we carry (this can be DNA or RNA viruses)
Global virome project = more than human virom
40-50% of the human genome originates of transposable elements
Most viruses are small: you need elektroscopes to visualize them
Many viruses are spherical, you can package a lot of material in a spherical form
Filamentus viruses (ebolavirus)
Complex viruses
There are also unusually large viruses: mimivirus, pandoravirus -> people thought it were bacteria
because they are very big
-> mostly found in amoebae
-> all of the viruses have double strand DNA, accept of the large viruses
All viruses are obligatory parasites
, Found to infect each life form
DNA or RNA as genetic material, single stranded of double, covered by a protein coat, some
have a lipid envelope
They need a host cell for energy production, protein synthesis and reproduction
All viral genomes are molecular parasites that can only function after they replicate in a cell
All viruses must make mRNA that is compatible with our own ribosome -> mRNA can be
translated by host ribosomes: they are all parasites of the host protein synthese machinery
Viruses are important disease-causing agents, but not all viruses make us sick
o Some are just passengers (breathing, food)
o Our immune system can deal with some viruses
Virus replication
1. virus enters the cell
2. transcription/replication: it needs to
make protein material in the cell -> virus vs. host defense
3. virus exits the cell
4. it can move to another host
1. inoculation: virus binds to cells
2. eclipse: virions penetrate the cells
3. burst: one cell makes a large amount of viral particles, a lot of cells will die
4. burst size: number of virions released per bacterium
Difference with bacterial cells
What are viruses ?
Most abundant biological entities on the planet
They need a living host to replicate
RNA or DNA that’s package in protein, some viruses have lipids
Major roles in global ecology and evolution of the biosphere
Obligate intracellular parasites that package their genomes into tiny protein/lipid particles
All organisms on the planet harbour distinctive repertoires of viruses
We breathe and eat billions of virus particles
Human DNA consists partly of ancestral viral genetic material
Number of viruses on earth: >10^16 HIV particles on Earth
More viruses in a liter of sea water than people on earth
Viruses are everywhere: plants, water, animals, food
The human microbiome = diversity of bacteria that we carry in our bodies
The human virome = viruses that live on bacteria/that feed on bacteria
-> determining which viruses we carry (this can be DNA or RNA viruses)
Global virome project = more than human virom
40-50% of the human genome originates of transposable elements
Most viruses are small: you need elektroscopes to visualize them
Many viruses are spherical, you can package a lot of material in a spherical form
Filamentus viruses (ebolavirus)
Complex viruses
There are also unusually large viruses: mimivirus, pandoravirus -> people thought it were bacteria
because they are very big
-> mostly found in amoebae
-> all of the viruses have double strand DNA, accept of the large viruses
All viruses are obligatory parasites
, Found to infect each life form
DNA or RNA as genetic material, single stranded of double, covered by a protein coat, some
have a lipid envelope
They need a host cell for energy production, protein synthesis and reproduction
All viral genomes are molecular parasites that can only function after they replicate in a cell
All viruses must make mRNA that is compatible with our own ribosome -> mRNA can be
translated by host ribosomes: they are all parasites of the host protein synthese machinery
Viruses are important disease-causing agents, but not all viruses make us sick
o Some are just passengers (breathing, food)
o Our immune system can deal with some viruses
Virus replication
1. virus enters the cell
2. transcription/replication: it needs to
make protein material in the cell -> virus vs. host defense
3. virus exits the cell
4. it can move to another host
1. inoculation: virus binds to cells
2. eclipse: virions penetrate the cells
3. burst: one cell makes a large amount of viral particles, a lot of cells will die
4. burst size: number of virions released per bacterium
Difference with bacterial cells
