virology Flashcards
difference of bacteria infection and all cells infected rate
Bacteria spread in a steady rate
while other spread in a burst rate
definition of a virus
infectious, obligate intracellular parasite containing genetic material
so if it don’t have a nucleic acid, its not virus
what particles that forms into a virus
genome (RNA/DNA)
Capsid
envelop
what type of cell do virus infect?
they have the ability to infect all type, but they have preferences
what is a basic virus structure consist of?
- nucleic acid
- capsid
- glycoprotein
- matrix protein
- envelope
what are the virus replication cycle
- attachment
- prenetration
- uncoating
- biosynthesis
- assembly
- release
what are the 3 internalisations stage?
- fusion –> they uncoated at the cellular external plasma membrane and allow the viral genetic material to go into the cytoplasm
- endocytosis –> the whole virus goes in surrounded by endosomes and uncoating within the cytoplasm
- intensive trafficking –> where the whole virus goes in through the endosome and releases viral RNA at the nuclear membrane
how many groups are in the Baltimore classification
7
what are the group in the Baltimore classification
group 1 - Double-stranded DNA
group 2 - Single-stranded DNA
group 3 - Double-stranded RNA
group 4 - Single-stranded RNA (+)
group 5 - Single-stranded RNA ( - )
group 6 - single-stranded RNA viruses with reverse transcriptase
group 7 - Double-stranded DNA viruses with reverse transcriptase
why viral genomes are the fastest evolving entities in biology?
- short replication time
- large numbers of progeny released per cell infected
- virus genomes display a higher mutation rate than cellular organisms
- their polymerases typically have a higher mutation rate than cellular polymerases
- High mutation rate often produces more deficient than infectious genomes
- rapid evolution through natural selection
what are the viral exit currently have for virsus
Budding-enveloped viruses take some cell membrane on their way out
cell lysis - viruses burst out of the cell
triggering apoptosis
exocytosis
how do viruses damage host cells
lysis
multinucleated syncytium (where cells are cluster up together)
transformation
What is a cytopathic effect (CPE)
Structural changes in the host cell because of viral infection
when will CPE occurs
when the cells dies without lysis because of its ability to reproduce
what kind of transmission can we get infected?
abrasion respiratory tract gastrointestinal tract Conjunctiva (loose connective tissue that covers the surface of the eyeball) genital tract
what is a viraemia
a medical condition where viruses enter the blood stream and be able to access to the rest of the body
example of viraemia
viraemia in plasma - polio
persistent viraemia
- Epstein Barr virus (EBV) in B-lymphocytes
- Huma immunodeficiency virus (HIV) in T-lymphocytes
what are the features in the acute infection
- recover by eliminating the virus
- recovery is followed by partial or complete immunity
examples of acute infection
- rhinovirus
- rotavirus
- influenza virus
features in persistent infection
evasion of the immune system
the ability of immunosuppression –> cause disease
latent so it can stay in the body for a long time
^ must be able to receive e.g. stress/trauma
what requirement does virus need to be able to spread in the host
- invade the host
- establish a local stronghold
- overcome local defences
- be able to spread from the site of entry to other areas
- be able to replicate in local area
- have a exit pathway to go and affect other area
why there is fewer antiviral drugs than antibiotics?
the drug used in targeting viruses tended to attack normal host cells as well
selective toxicity - harder to find a point of attack when constantly used
lack of rapid diagnostics
no broad-spectrum antivirals
viruses replicate intracellular, so drug need to penetrate cell to inhibit here
they must be very effective to prevent for resistance
where is the good way to inhibit viral infections?
inhibit the nucleic acid synthesis
protease inhibitors
inhibit penetration
immunomodulators
what is varicella zoster virus (VZV)
primary infection that causes chicken pox
what is MMR
Measles-mumps-rubella
what is the general principles of the spread of the virus?
horizontal spread - e.g. air, water, food, contact
vertical spread - e.g. sexual contact, contaminated breast feeding
