Virology Flashcards
Of all the microorg, which is the smallest
Virus
Virus are obligate parasites . What does it mean
It means they need a host to survive. They can’t survive without a host
What is virus made up of
Nucleic acid and a protein coat
Characteristics of virus
They reproduce rapidly
Can’t reproduce without a host
They don’t have ribosomes so they can’t synthesize proteins
So they depend on the host’s ribosomes
They can’t produce energy so they depend on the host to get energy
Structure of the virus
From the outer portion :Envelope( made up of either lipid,protein,carbs)
Tergument
Capsid
Nucleic acid
Some virus produce enzymes. Give an example
HIV
Structure of virus
Spherical
Fillamentous
If a virus has an envelope made up of carbs and proteins what wil the name of the envelope be
Glycoprotein envelope
And it will surround the nucleocapsid
The projection on the outer layer of the virus are called? And what is their function
Spikes
They enable the virus to hook onto cells for attachment
Tergument is a protein that doesn’t have a fixed shape. True or false
True
Most proteins of the virus are found where
In the tergument
Antigen antibody test detects what in the virus
The protein in the virus
Function of the capsid
It gives the solid structure of the viruses and covers the nucleic acid and forms the nucleocapsid.
Inside the capsid is the nucleic acid so It protects the inner structure of the nucleic acid.
Enables virus to attach itself to the surface of the host and gain penetration into the host
Not all viruses have envelopes. Give an example
Ebola virus
Polio virus
HIV has envelope
Most viruses at which nucleic acid
RNA
With DNA, either they are double stranded or single stranded DNA and with RNA either they are double stranded or single stranded RNA true or false
True
Some RNA are positive strands and helps the virus replicate fast. How?
They can easily be converted into messenger RNA and then leads to protein translation
Some RNA are negative strands. What does it mean
They need another enzyme to convert the RNA into something for protein synthesis
Positive-sense viral RNA is similar to mRNA and thus can be immediately translated by the host cell. Negative-sense viral RNA is complementary to mRNA and thus must be converted to positive-sense RNA by an RNA polymerase before translation.
What is reverse transcriptase
A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by certain viruses such as HIV and the hepatitis B virus
Name two other Structure of viruses based on nucleic acid and structural proteins
Viroids- have only nucleic acid but no structural protein
Prions- looks like virus but aren’t virus( they’re composed mainly of protein tightly integrated w a small nucleic acid molecule
Rabies virus is the only virus with a bullet shape true or false
True
What is the suffix of the family and genus of viruses
Viridae and genus is virus
Which properties of viruses help them to be classified
Genome properties: type of nucleic acid, size of genome in kilo based or kilo base pairs, segments
Morphology: sizes, shapes, type of capsid, symmetry
Physiochemical-pH, stability, there
Al stability, susceptibility to physical and chemical agents
Nature of the host- plant host or animal host
Antigenic properties
Biological properties- method of transmission, disease caused
Symmetry types of viruses
Helical o
Give two advantages of classification of viruses
Prompt identification of organisms for appropriate diagnosis and treatment
To understand how the organisms causes diseases ( the pathogenicity of the organism)
Name four sources of viral infections
Viruses don’t grow in every cell
- Saliva- rabies in dogs
- Faeces - virus multiplication in small intestine example enteroviruses (example,polio)
- Blood example HIV
- Urine example Lassa fever
- Body fluid example chicken pox
Name the processes by which viruses infect
- Primary replication
- Systemic Spread
- Secondary replication
- Cell tropism
- Cell death
- Immune response
- Viral clearance or resistance
Explain how virus infects
- When virus enters the body, they go into incubation period and multiply. 2.They start spreading thru the blood system. Then they go to specific organs of the body through the secondary lymph nodes. ( near the armpit)
3.They replicate more in the lymph nodes then they move into the cells and they attacking the organs and the tissues - Viruses affinity for specific body tissues( cell tropism) . Every virus has a receptor it can attach to to enter the host.
When they enter the cytoplasm of the host, they shed off their protein coat cuz the Niclic acid will tell the host to make a copy of the viruses nucleic acid. Then when the copies are made, they put on the protein coat and then come out of the cell. If it’s an RNA virus it produces the mRNA and leads to the production of the proteins and the proteins come out with the protein coat
5.They cause cells to die
When this occurs, the immune system tries to attack the virus and clear it or overcome it. Then it spread into the systems and causes diseases
Roles of secretory bodies
- Cellular immune response : production of T cells
2. Humoral immune response :leads to the production of antibodies
Pathogenesis of viral infections
Ability of the virus to enter the host and cause disease
Infection is the ability of the virus to enter the host whether it causes an infection or not
Viral replication Adsorption or attachment Entry or penetration Uncoating Transcription Synthesis of virus components Assembly Release
When is a person said to be subclinical
Viral infections are not able to produce symptoms in the host
Why is the behavior of the virus receptor called lock and key
Example: polio virus can’t enter CD4 T cells cuz they don’t have a ligand or door for polio virus to enter to cause harm.
When virus has a specific receptor for the ligand or door on the target cell then it attaches to it