Introduction to virology Flashcards
Who discovered the first plant virus and in which year? What was the name of the virus?
Tobacco mosaic virus was discovered in 1892 by Dmriti Ivanowski (DI) and Martinus Beijernick (MB)
First animal virus to be discovered was —- in the year ____? Who discovered it?
- Foot-and-mouth disease virus in the year 1898
- Paul Frosch and Friedrich Lauffler
Proper definition of viruses?
- ultra-filterable
- ultra-visible
organisms that cannot grow on dead substrates
Characteristics of viruses?
- obligate, intracellular parasites
- no enzymes for energy acquisition
- no machinery for protein synthesis
- no organelles
- no cellular organization
- no multiplication by division or reproduction
- has either dna or rna
what does the general structure of viruses contain?
- envelope made up of protein and lipid bilayer
- capsid of protein
- genome
- accessory proteins
Size of viruses
10 raise to the power of -7 to -9
Who discovered the first electron microscope? and which virus did he view and which year?
Helmut Ruska in 1938
Three main structures of viruses?
- Icosahedron
- helical
- complex
What are the important principles for a virus structure?
- closed shell for protection
- genetic economy
-specific strategies for entry and exit
“Protein subunits spare
coding capacity and
represent redundant
antigens” Explain.
This means that the protein subunits act as redundant antigens which means that they can act or function as the original proteins if it is unavailable or doesn’t work properly which means that helps to ensure that the virus will work even under unfavorable situations.
Simplest package is a shell that can assemble spontaneously ________
from a single component.
Identical subunits with specific interactions in general produce _____
symmetric structures
The ________ is the most efficient form (most viruses)
Regular isocahedron
What determines the shape of capsids?
The number of hedrons and pentons
- Envelopes are ______
- Infectivity dependent on _________
- Protein subunits represent _____
- Modified cellular membranes
- nucleic acid
- coding capacity
Connected to the disease:
Based on location first found:
Host and disease:
Discoverer:
According to the assumed origin
Combinations:
- Measles virus
- Ebola virus
- Tobacco Mosaic Virus
- Epstein-Barr Virus
- Influenza
- Rous Sarcoma virus
What are the ways of classifying a virus?
- Nucleic acid of the genome
- Genome type
- Shape of nucleocapsid
- Enveloped nucleocapsid or not
- Organ tropism or pathogenesis
- Location and mode of maturation and replication
- Genotype and serotype
Structure of adenovirus?
- two protein species: Hexons and Pentons
- Three Hexons are arranged in a triangular shape
- Pentons are made up of penton base and they basically attach the other viral components
- there are 12 pentons and 240 hexons in the structure
Ending of:
Family
Order
Subfamily
number of orders and number of families
Viridae
Virales
Virinae
8 and 125
Facts about Human Papillomviruses:
1. How many HPV types are known to affect humans? What is their genome?
2. About 40 HPV genotypes spread ___
3. Prevalence of HPV in females
4. _____ HPV genotypes („high risk“ HPVs) are recognized as the major cause of
_____
5. Two most common types of HPV
- more than 100, their genome is dsDNA
- through sexual contact
- 2-44%
- 15, cervical cancer
- HPV16 and HPV18
Dengue virus:
Family? Mode of transmission?
How is it classified?
A different phenomenon?
How many serotypes? Type of genome?
Flaviridae, through mosquitoes
On the basis of the antigens on their surface
ADE
4. SS RNA (enveloped)
What is the baltimore classification of viruses? Give examples.
ddDNA - Herpes and adenovirus
ssDNA - parvoviruses
ddRNA - Reoviruses
positive sense ssRNA - coronavirus
negative sense ssRNA - influenza and measles viruses
Reverse transcriptase - Retroviruses
DNA with an intermediate RNA - Hepatitis B Virus
What are the different types of non-persitent and persistent viruses?
- a. cytocidal - the infected cells are destroyed, b. non-cytocidal cells: the infected cells are not destroyed and they continue to cause infection.
- Chronic: continue to stay in the body for many months and years.
Latent: stay inactive in the body for sometime
Transforming: get integrated into the host genome and cause changes which may be passed onto the progeny
What is the Henry Ford principle?
Basically, the viruses do not replicate themselves and instead make use of the host machinery to replicate their proteins and their genomes. This shows that viruses show an efficiency principle to maximise the production of their particles.
What are the important steps of the multiplication cycle of piconarvirus?
- adsoption
- penetration
- uncoating
- transcription and replication
- protein synthesis
- assembly
- egress
Genome replication, capsid
assembly und genome
packing in ____
- assembly of infectious
virus particles ____
- Nucleus
- Cytoplasm
Important structures of virus:
- Nucleocapsid
- Tegument - important for regulating gene expression
- Envelope
- GC 1, GC2 and GC3 - stop codons to stop protein synthesis
- GPCR (G-protein coupled receptor) - for cell communication and for recognizing cell receptors
