Fichas
Viruses
Fichas del conjunto (29)
- 1How big are viruses in comparison with bacertica and rbc?The smallest infectious agent
(except prion and plasmid) - 2What is the structure of viruses?Only one type of nucleic acid in a protein coat (capsid)
- 3Are viruses considered to be living cells?No
- 4What are the types of nucleic acids in viruses?ssRNA
dsRNA
ssDNA
dsDNA - 5What is the viral capsid made of?Protein coat covering nucleic acid
Arranged in crystallized pattern
Capsid proteins may have antigenic properties (able to stimulate immune system to produce immune response), participate in attachment and entry of virus into host cell, protect nucleic acid against inactivation by nuclease enzymes. e.g. T2 bacteriophage legs attach to bacteria - 6What is the envelope?Lipid bilayer from the membrane of host cell with specific viral proteins and glycoproteins.
Glycoproteins may appear as spikes that assist virus in attaching
Viruses without envelope = naked virus
More resistant to environmental conditions - 7What are viral enzymes?Some viruses contain genes for enzyme production that are important in infective process.
- 8How are viruses classified?Type of nucleic acid they contain
Their shape and structure (cynlindrical, naked, envelope)
Method of replication - 9How are viruses specific to hosts?Highly selective for hosts and type of cell they infect.
Plant viruses only infect plant, bacterial viruses only infect bacteria, animal viruses only infect animals
BUT some cross species barrier & infect birds and animals
Some recognise more than one recepter e.g. liver cells and gut cells
If the receptors are on different types of cells the range on cells virus can attack is extended.
Susceptibility of host cell determined by presence of absence of receptor molcules - 10How is the susceptibility of the host cell determined?Presence or absence of receptor molcules
- 11What is an animal reservoir?Virus lives and replicates in animal like water stores in reservoir.
What animal comes in contact with human the reservoir opens up and begins causing problems. - 12What are the stages of viral replication?1. Adsorption: attachment to specific receptor site
2. Penetration: enters the cell by direct penetration, membrane fusion or phagocytosis
3. Uncoating: virus dismantled in host cell and nucleic released into cytoplasm
4. Synthesis: nucleic acid copied, viral genes directing synthesis of viral messenger RNA and new viral capsid proteins and enzymes.
5. Assembly of Virus Capsomeres and Nucleic Acid
6. Release: naked viruses released and cell lysis occurs. Enveloped viruses bud out through cell membrane. - 13How do viruses cause disease?Viral disease is a result of viral infection
Response to infection: no apparent effect, cellular damage affecting organ function, hyperplasia, cancer - 14What is the nature of a viral disease?Can be
Acute (sudden, short duration)
Subclinical (didn't know it happened)
Persistent (long duration)
Latent (just lives with symptoms every now and then)
Chronic (last a long time and always have)
Slow
Oncongenic (cancer) - 15How does the host respond to viruses?Depends on type of virus and susceptibility of host
Virus usually spread by blood or lymphatic system
Provokes production and release of interferon from infected cells
Activation of T lymphocytes (identify and destroy infected cells)
Production of lymphokines and other cytokines
Activation of B lymphocytes and production of antibodies
Production of memory cells
Immune system activation and production of interferon and cytokines produce symptoms of viral disease - 16How can you treat a virus?Treat symptoms
Recovery depends on ability to remove virus
Age and status of immune system determines susceptibility - 17What are viral evasion strategies?1. hide in infected cells. not expressed on outside therefore protected from cytotoxic T cells
2. change appearance. previously formed antibodies no longer effective
3. become latent
4. manipulate host immune system. destroy T cells, hide in macrophages. - 18How are viral disease trasmitted via airborne?Shed where infection is localised.
e.g. infection of mucosal cells in upper respiratory tract results in virions shed in aerosol droplets when cough or sneeze. - 19How are viral diseased transmitted via faecal - oral route?Gastrointestinal infections shed in faeces.
Faecal contamination of food or water - 20How are viral diseases transmitted via body fluids?Sometimes by organ transplantation if proper screening procedures aren't used.
- 21How are viral diseases transmitted by vectors?Carry the virus from infected host to susceptible human.
Ingests virus from infected human through feeding
Replicates in gut of insect vector
Spreads to salivary glands
Injected into a susceptible host during next blood meal. - 22How are viral diseases transmitted via teratogenic effects?Damage to unborn foetus.
Virus crosses placenta or acquired by neonate when blood mixes at delivery. - 23How are viruses inactivated?Variable length of time virus can survive outside host cell and physical and chemical conditions it can withstand.
Most viruses destroyed by heat and 60 degrees for 30 mins. - 24How are viral infections diagnosed?Signs and symptoms.
- 25What is immunofluorescence?Fluorescent labeled antibody.
Observed with fluorescent microscope. - 26What is nucleic acid analysis?Tests for presence of live viruses in serum or tissue.
- 27What is serology?Detection of viral antigens and antibodies in body tissues.
- 28What is cell culture?Viruses grown inside a living cell.
Difficult, expensive, time consuming. - 29How do antiviral drugs affect the host?Adverse effect on host cell
Limited number developed
Información
- Descripción
- University (Semester 1) Microbiology Fichas sobre Viruses, creado por Hannah Waters el 08/06/2016.
- Creado por
- Hannah Waters · jun 2016
- Actualizado
- 23 ago 2016
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