virology Flashcards
(29 cards)
the most abundant life form
in the human body.
Bacteriophage
what diseases can viruses cause?
Viruses can cause acute, persistent and recurrent diseases
integrated endogenous retroviruses
part of our genetic material. Our chromosomes contain large amounts of ancient viral DNA
accumulated during evolution.
(Retroviruses are the
family to which HIV belongs.)
whats virus?
RNA or DNA genome wrapped in a protein coat
and frequently also a lipid coat.
-obligate intracellular parassite
viruses replication
de novo assembly of preformed components
( not like bacteria)
virion->viral genome->viral components->new virions
ancient viruses
polio smallpox (hep B) rabies measles yellow fever
germ theory
was’t acceptable until mid-late 1800s
the idea is that we are sick by the infectious agents
Recent emergent viral diseases North America: • HIV/AIDS • Hantavirus pulmonary syndrome • West Nile virus encephalitis • Severe acute respiratory syndrome (SARS) • Ebola • Zika
• HIV/AIDS (HIV-1 is from chimpanzees)
• Hantavirus pulmonary syndrome (rats and mice)
• West Nile virus encephalitis (birds, mosquitos)
• Severe acute respiratory syndrome (SARS) (civets)
• Ebola (probably bats)
• Zika (nonhuman primates, mosquitos
These are all zoonotic transmissions
acute flaccid myelitis, or AFM
it is caused by a
virus called EV-D68
• Phylogeny:
Viruses are classified into families, genera and species (and strains, clades).
Capsid structure
icosahedral, helical, complex
viruses can be divided by the viral genome
RNA or DNA in the virion
Segmented or non-segmented
single or double stranded
(+) sense or (–) sense
dna viruses
Herpes
Adeno
Papova
Poxvirus
2 things that virus does
- make a genome in nucleus or cytoplasm
2. make a varion to pack that genome
capsid
is a protein coat around the genome of the virus
envelope
- capsid+lipid bilayer
- have spikes(envelope proteins=envelope glycoproteins)
- bud from cell or intracellular membrane( cell dies or survives)
Ex: Herpesvirus
HIV1
Influenza
naked virus
- capsid only
- mostly emerge from cells by cell lysis (cell dies)
- have spikes for binding
Ex: Adenovirus
Picornavirus
Envelope proteins
-mediate attachment and entry of
enveloped viruses into cells and are the major determinant
of cell tropism.
-major viral antigens.
nucleocapsid
capsid + viral genome
This is true for both naked and enveloped viruses
enveloped viruses Sensitive to:
detergents
heat
drying
bleach
spread by: direct contact, saliva, blood, sex
naked viruses Can be resistant to:
detergents heat drying pH proteases
spread by
-contact with surfaces,
-poorly sanitized water.
- often spread via fecal-oral route:
Hepatitis A virus (HAV), Poliovirus, Rotavirus, Coxsackie Virus.
Rhinoviruses are spread by intake of nasal mucous.
Icosahedral capsid
- most animal viruses have an icosahedral capsid(20 sides)
-Best way to maximize internal volume with minimal number of similar subunits.
-12 vertices - with 5 fold symmetry
-Pentons make up the vertices (5 fold symmetry, curved)
-Hexons make up the sides( 6 fold symmetry, flat)
Ex: Gastroenteritis (GASP)
Adenovirus
Strep throat
Pneumonia
helical capsid
- human helical viruses all have RNA genomes
e.g. influenza virus
tobacco mosaic virus
paramyxovirus
rhabdovirus
Complex
- pox viruses - helical structure plus
some other structures that are not
understood.
