CH3-S1

Question 1

What is virus?

Answer 1

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.

Question 2

Structure of viruses has ____ basic components. They are ______.

Answer 2

2, nucleic acid and capsid

Question 3

What is nucleic acid?

Answer 3

Single- or double-stranded RNA or DNA

Question 4

What is capsid?

Answer 4

Protein coat that surrounds and protects the viral genome

Question 5

A fully formed virus that is able to establish and infection in a host cell is often called a ____

Answer 5

virion

Question 6

Viruses are enveloped or naked. Some envelopes have spikes - glycoproteins. T/F

Answer 6

T

Question 7

Taxonomy of viruses: maybe start from the classical hierarchical system - Order -> Family -> Genus -> Species. Give an example.

Answer 7

Family: Herpesviridae, Genus: Herpesvirus, Species: Human herpes virus HHV-1

Question 8

Viruses undergo binary fission. T/F

Answer 8

F

Question 9

Describe the viral life cycle

Answer 9

1. 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

Question 10

Describe the process of viruses replication

Answer 10

1. 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)

Question 11

Compare DNA viruses and RNA viruses

Answer 11

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.

Question 12

Give an example for RNA viruses

Answer 12

Retroviruses (replicate through a DNA intermediate)

Question 13

Four types of influenza viruses: __, ___, ___, ____

Answer 13

A,B,C,D

Question 14

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

Answer 14

A

Question 15

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

Answer 15

drift

Question 16

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

Answer 16

shift

Question 17

Give an example of antigenic shift

Answer 17

2009 H1N1 pandemic strain (reassortant of avian, human and swine influenza viruses)

Question 18

HIV cause ____

Answer 18

AIDS

Question 19

Describe the type of HIV (human immunodeficiency virus) and the process it infects the cell

Answer 19

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.

Question 19

Describe the type of SARS-CoV-2 (Severe acute respiratory syndrome coronavirus-2) and the process it infects the cell

Answer 19

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.

Question 20

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.

Answer 20

SARS-CoV-2 / RNA-enveloped virus, spike protein, (angiotensin-converting enzyme 2) ACE2 receptor

Question 20

______ is a very inaccurate DNA polymerase, leading to high _____ rate

Answer 20

Reverse transcriptase, mutation

Question 21

_____ transform normal cells into cancerous cells

Answer 21

Oncogenic viruses

Question 22

Give one example of oncogenic viruses and its developed cancer

Answer 22

Hepatitis B virus and Hepatitis C virus -> liver cancer

Question 23

______ effects is the changes in host cells that are caused by viral invasion

Answer 23

Cytopathic

Question 24

List 7 cytopathic effects

Answer 24

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

Question 25

Cultivation of viruses: viruses must be grown in living cells - _____ form plaques on a lawn of bacteria

Answer 25

bacteriophages

Question 26

Cultivation of viruses: viruses must be grown in living cells - _____ may be grown in cell culture, embryonated eggs, or living animals

Answer 26

animal viruses

Question 27

List 3 ways of viral identification

Answer 27

Cytopathic effects, serological tests (use antibodies to identify viruses), revolutionary methos e.g. polymerase chain reaction (PCR): amplification of a selected DNA sequence

Question 28

Prions are small _____ _____ particles (‘misfolded’ protein, very resistant to inactivation)

Answer 28

proteinaceous infectious

Question 29

Prion diseases occur when ____________________

Answer 29

normal prion protein found on the surface of many cells, becomes abnormal and clumps in the brain, causing brain damage.

Question 30

Accumulation of prion in the brain can cause _____________

Answer 30

memory impairment, personality changes and difficulties with movement

Question 31

Risk factors for prion disease include: __________________

Answer 31

Family history of prion disease, eating meat infected by “mad cow disease”, infection from receiving contaminated corneas or from contaminated medical equipment

Question 32

_____ cause transmissible spongiform encephalopathies: _________ and _____

Answer 32

Prions, Creutzfeldt-Jakob disease(克雅二氏症), Kuru

Question 33

All known _____ disease affect the nervous system and are ________, resulting in _______

Answer 33

prion, untreatable, 100% fatality

Question 34

Creutzfeldt-Jakob disease deteriorate the brain and fill it with ____ -> personality changes, _______ -> ________

Answer 34

holes, impaired vision, difficulties with muscular coordination, insomnia and depression, dementia and severe mental impairment