CH3-S1 Flashcards
What is virus?
A small infectious, obligate intracellular parasite. It contains either a RNA or DNA genome surrounded by a protective, virus-coded protein coat. Viral genome contains information to initiate and complete and infectious cycle within a cell. A virus can quickly make multiple copies of itself in one cell, release these copies to infect new host cells and make even more copies.
Structure of viruses has ____ basic components. They are ______.
2, nucleic acid and capsid
What is nucleic acid?
Single- or double-stranded RNA or DNA
What is capsid?
Protein coat that surrounds and protects the viral genome
A fully formed virus that is able to establish and infection in a host cell is often called a ____
virion
Viruses are enveloped or naked. Some envelopes have spikes - glycoproteins. T/F
T
Taxonomy of viruses: maybe start from the classical hierarchical system - Order -> Family -> Genus -> Species. Give an example.
Family: Herpesviridae, Genus: Herpesvirus, Species: Human herpes virus HHV-1
Viruses undergo binary fission. T/F
F
Describe the viral life cycle
- Inoculation: inoculum of virus binds to cells 2. Eclipse: virions penetrate the cells 3. Burst: host cells release many viral particles 4. Burst size: number of virions released per bacterium
Describe the process of viruses replication
- Adsorption: binding of virus to specific molecule on host cell 2. Penetration: the virion is endocytosed and contained within a cytoplasmic vacuole 3. Uncoating: the viral nucleic acid is released from the capsid 4. Biosynthesis (Viral nucleic acid replication) : viral components are produced 5. Assembly: new viral particles are constructed 6. Release: assembled viruses are released by budding (exocytosis)(do not usually kill the infected cell) or cell lysis (death of the infected host cell)
Compare DNA viruses and RNA viruses
DNA viruses’s genetic material is DNA. RNA viruses’s genetic material is RNA. RNA viruses are also comprising 70% of all viruses. RNA viruses have a higher mutation rates than DNA viruses. And the continuous generation of DNA virus variants may have greater adaptability to new hosts.
Give an example for RNA viruses
Retroviruses (replicate through a DNA intermediate)
Four types of influenza viruses: __, ___, ___, ____
A,B,C,D
Influenza type ___ viruses are subtyped based upon the hemagglutinin (HA) (for binding) and neuraminidase (NA) (for releasing) antigens, which are surface proteins found on the viral envelope
A
Antigenic _____ : small changes in the genes, theses changes can accumulate over time and result in viruses that are antigenically different, result in repeated epidemics observed with influenza A or B virus
drift
Antigenic _____ : influenza viruses have segmented genome, genetic reassortment occur when two influenza viruses infect the same cell, result in a major and sudden change in genetic makeup of the virus
shift
Give an example of antigenic shift
2009 H1N1 pandemic strain (reassortant of avian, human and swine influenza viruses)
HIV cause ____
AIDS
Describe the type of HIV (human immunodeficiency virus) and the process it infects the cell
RNA-enveloped retroviruses. Once inside the cell, viral RNA is converted to DNA in a process called reverse transcription, viral DNA then integrates into the chromosome of the host, as the virus leaves the cell it disrupts the cell membrane leading to host cell death.
Describe the type of SARS-CoV-2 (Severe acute respiratory syndrome coronavirus-2) and the process it infects the cell
RNA-enveloped virus. Binding of the coronavirus spike protein to the host cell angiotensin-converting enzyme 2 (ACE2) receptor mediates viral cell entry. Once inside cells, viral RNA is replicated, and structural proteins are synthesized, assembled, and packaged in the host cell, after which viral particles are released.
The process of _____ infection:
Binding of the coronavirus _______ to the host cell ________ mediates viral cell entry. Once inside cells, viral RNA is replicated, and structural proteins are synthesized, assembled, and packaged in the host cell, after which viral particles are released.
SARS-CoV-2 / RNA-enveloped virus, spike protein, (angiotensin-converting enzyme 2) ACE2 receptor
______ is a very inaccurate DNA polymerase, leading to high _____ rate
Reverse transcriptase, mutation
_____ transform normal cells into cancerous cells
Oncogenic viruses
Give one example of oncogenic viruses and its developed cancer
Hepatitis B virus and Hepatitis C virus -> liver cancer
______ effects is the changes in host cells that are caused by viral invasion
Cytopathic
List 7 cytopathic effects
Changes in cell size & shape, formation of cytoplasmic inclusion bodies, formation of nuclear inclusion bodies, cells fuse to form multinucleated cells, cell lysis, alter DNA, transform cells into cancerous cells
Cultivation of viruses: viruses must be grown in living cells - _____ form plaques on a lawn of bacteria
bacteriophages
Cultivation of viruses: viruses must be grown in living cells - _____ may be grown in cell culture, embryonated eggs, or living animals
animal viruses
List 3 ways of viral identification
Cytopathic effects, serological tests (use antibodies to identify viruses), revolutionary methos e.g. polymerase chain reaction (PCR): amplification of a selected DNA sequence
Prions are small _____ _____ particles (‘misfolded’ protein, very resistant to inactivation)
proteinaceous infectious
Prion diseases occur when ____________________
normal prion protein found on the surface of many cells, becomes abnormal and clumps in the brain, causing brain damage.
Accumulation of prion in the brain can cause _____________
memory impairment, personality changes and difficulties with movement
Risk factors for prion disease include: __________________
Family history of prion disease, eating meat infected by “mad cow disease”, infection from receiving contaminated corneas or from contaminated medical equipment
_____ cause transmissible spongiform encephalopathies: _________ and _____
Prions, Creutzfeldt-Jakob disease(克雅二氏症), Kuru
All known _____ disease affect the nervous system and are ________, resulting in _______
prion, untreatable, 100% fatality
Creutzfeldt-Jakob disease deteriorate the brain and fill it with ____ -> personality changes, _______ -> ________
holes, impaired vision, difficulties with muscular coordination, insomnia and depression, dementia and severe mental impairment
