VIRUSES Flashcards
What are viruses? ()
Are disease causing agents, which lack a metabolism of their own so depends on the metabolism of the cells they infect
What is the structure of a virus? (2)
Have a core nuclei acid around it which is a protein coat called a capsid, some have an additional external envelope of membrane made of lipids and proteins for example the human immunodeficiency virus
Where do antivirals work where they have been developed? ( 1)
Where antivirals have been developed, they musi work by inhabiting viral replication by the chostcells
How do antivirus work where they have not been developed? (1)
’ Where anti virals have not been developed disease control must rely on preventing the spread of the virus.
How do we classify viruses?
Classifying relys on features such as: - the nature and method of copying the nuclei acid cure
- the nature of their capsid
- their shape
- the organisms they infect
What are 4 types of virus? (4)
- ( lambda )bacteriophage
-tobacco mosaic virus
-Ebola virus - human immunodeficiency virus
What host organism does the (lambda) bacteriophage infect? (1)
Usually bacterium escherichia coli
What is the structure of a (lambda) bacteriophage virus? (2)
Has a head, tail and tail fibre.
What is the nature of the nuclei acid core in a (lambda) bacteriophage? (1)
Is double stranded DNA.
What is the copying of the nucleic core in a (lambda) bacteriophage? (1)
Is double stranded DNA transcribed to mRNA.
What host do the tobacco mosaic virus infect? (1)
Plants, especially those in the tobacco family.
What is the structure of a tobacco mosaic virus? (1)
Has a protein coat (capsid) of polypeptide building blocks arranged in a spiral around the canal containing RNA.
What is the nature of the nucleic acid core of a tobacco mosaic virus? (1)
Is a single stranded RNA.
What is the copying of the nucleus acid core in the tobacco mosaic virus? (1)
RNA copied directly to form mRNA.
What host does the Ebola virus infect? (1)
Humans, especially endothelial cells, liver cells, immune cells and dendritic cells.
What is the structure of the Ebola virus? (2)
RNA and outer protein coat.
What is the nature of the nucleuic acid core in a Ebola virus?
Is a single stranded RNA.
What is the copying of the nucleic acid core in an Ebola virus?
RNA copied directly to form mRNA.
What host does the human immunodeficiency virus infect? (1)
Humans, the helper lymphocytes.
What is the structure of the human immunodeficiency virus? (5)
Enzymes, protein coat, capsule, glycoprotein and single stranded RNA.
What is the nature of the nucleic acid core in the human immunodeficiency virus? (1)
Single stranded RNA.
What is copying of the nucleic acid core in the human immunodeficiency virus? (1)
RNA reverse transcribed into a double stranded DNA which is incorporated into the host cells DNA and later transcribed to form mRNA.
What is viral latency? (2)
A period in which under the control of specific latency genes, a pathogenic virus remains dorment. During this time the virus, or its nucleic acid is present inside an infected cell but does not control the cells activities.
What are the two types of viral latency? (2)
-episomal latency
-proviral latency
What is episomal latency? (1)
The viral nucleic acid remains inactive but free in the cytoplasm or nucleus of the infected cell.
What is proviral latency? (1)
The viral nucleic acid becomes incorporated into the DNA of the infected host cell. It is now termed a provirus but, as with episomal latency, the viral nucleic acid can be reactivated at any time.
What virus is chicken pox caused by? (1)
Caused by the virus called varicella zoster.
What is the lytic cycle? (2)
In which the viral genetic material replicated independently of host DNA. New viruses are released by lysis. Such viruses are said to be virulent (disease causing).
What is the lysogenic cycle? (2)
In which the viral nucleic acid is incorporated into the host cell genetic material and spread through host-cell reproduction. The viral nucleic acid may remain inactive (latent) for years before it starts to replicate. Such viruses are termed non-virulent.
What is the retrovirus cycle? (2)
The retrovirus cycle is a special case of the lysogenic cycle.
The RNA is transcribed to DNA by reverse transcriptase in the host-cell. Viruses leave the cell by exocytosis (not lysis). The host cell continues to make viruses and new ones infect other cells.
What are the ethical considerations when using a drug that has not been fully trialed? (6)
-the severity of the disease.
-the availability of any other treatments.
-the effectiveness of disease control.
-problems with haltering the spread of the disease.
-transparency about the process.
-informed consent and freedom of choice.
What is classified in pre-clinical research of drug development? (3)
-discovery and early screening of compound.
-large-scale synthesis.
-animal testing.
How long does pre-clinical testing last? (1)
At least 5 years
What is involved in phase one of any trail for drug development? (1)
Is assessed on a small number of participants to assess safety.
How long does phase 1 usually last, in terms of trials of drug development?(1)
1.5 years.
What happens within phase 2 of any trial of drug development?(1)
Tested on over 10 participants, to study efficacy.
How long does phase 2 usually last ,in terms of trials for drug development?(1)
2 years.
What happens within phase 3 of any trials in drug development? (1)
Tested on over 1000 participants, to study safety, efficacy and dosing.
How long is phase 3, in terms of trails of drug development? (1)
3.5 years.
What was the name of the vaccination for Ebola? (1)
rVSV-ZEBOV
When was the vaccination for Ebola produced? (1)
In July 2015
