Week 1 Lectures Flashcards
Define the term virus.
Virus means slimy liquid or poison.
Viruses are submicroscopic __________ (______ microns) infectious agents that multiply only in _________ _______.
filterable, < 0.2, living cells.
List three examples of mediums in which viruses can grow.
Agar agar
M. Agar
Chicken eggs
Viruses are __________ parasites that are metabolically inert when they are ________ their hosts.
obligate, outside
Define obligate parasites.
Obligate parasites must be inside a cell to replicate.
Viruses rely, to varying extents, on the __________ _________ of their hosts to _______ ________.
metabolic processes, reproduce themselves.
True or False: Do viruses have cellular organelles?
Give examples.
No
Mitochondria, chloroplasts, GA, ER, ribosomes.
Viruses have nucleic acids in the form of ______ or _______ but _______ both except in the case of ___________.
DNA, RNA, never, retroviruses.
Virions are the _________ ________ __________ viral particle produced by the ________ cells under the control of the _______ materials of the virus.
mature, extracellular, infectious, infected, genetic
Viroids are infectious entities that affect _______, are ________ than a virus and consist only of nucleic acids without a ________ _______.
plants, smaller, protein coat
Satellite or Defective Viruses require a _______ _______ (_______ virus) for replication.
Provide an example.
second, virus, helper
Ex: Hepatitis delta virus requires the presence of HBV to complete its replication cycle.
Living Criteria of viruses
Inside the virus permissive cells
• Viruses ____ and ____ cellular functions for their own purposes
• Viruses can ____
- ___ genome
- _____ code
- new viral components are ______ and _______ within the infected ____ cell
• Viruses may undergo _____ which affect the genotype which will be reflected phenotypically in the virus structure.
control, divert, multiply, viral, genetic, synthesized, assembled, host, mutations
Nonliving criteria of viruses
• Viruses are not able to ______ on their own
• Viruses must infect ___ cells in order to perpetuate their life cycle
• Viruses can be _______ but no other cells can be
• Viruses do not have _____ generating (___) machinery
• Viruses do not have _____ machinery
• Viruses do not have the necessary machinery for generating ______ ___ or ____
• Viruses do not contain ______ or any _____ _____
• Viruses may contain ______ ______ derived from the infected host cells during viral exit
reproduce, other, crystallized, energy, ATP, metabolic, nucleic acid, protein, cytoplasm, cellular organelles, membranous envelope
Describe the non-life viral theory
Viruses are considered to be non-living because they
-Are not ___
-Do not ____ or respond to their ______
-Can not make ___, take in ____, or produce _____
-They do not respond to ____
cells, grow, surroundings, food, food, wastes, stimuli
Describe the life viral theory
The viral life theory has only two fundamental characteristics of the living system
1- the presence of ____ ____ as genetic material
2- the ability to _____ and produce their own ___.
Viruses can only multiply in _______
_____
nucleic acid, replicate, copies,another cell
Are viruses living or non-living?
Conclusion: viruses are nonliving outside the cells but live inside the cell
Which of the following can be isolated and propagated on synthetic media?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: Bacteria, mycoplasma
No: Rickettsia, Chlamydia, Viruses
Which of the following can undergo binary fission?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A, B, C, D
No: E
Viruses replicate in a different way
Which of the following contain both RNA and DNA?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A, B, C,D
No: E
Which of the following contain energy machinery?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A-D
No: E
Which of the following are effected by antibiotics?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A-D
No: E
Which of the following can perform metabolism?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A-D
No: E
Which of the following is greater than 300 nm in size?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A-D
No: E
Which of the following can be detected by light microscopy?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A-D
No: E
Most viruses can only be seen under EM except in cases of giant viruses as Mimivirus can be seen by light microscope.
Which of the following have a sensitivity to interferons?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: E
No: A-D
Which of the following possess a cell wall?
A. Bacteria
B. Mycoplasma
C. Rickettsia
D. Chlamdyia
E. Viruses
Yes: A, C, D
No: B, E
Mutation rates are primarily determined by the type of _____ _____ ______.
_________ mutation may not cause changes genotypically or phenotyically. Viruses mutate frequently, rate of mutation of DNA viruses is ____ then RNA viruses. Most viruses that spread rapidly are ____ viruses.
viral nucleic acids
Ongoing, less, RNA
A viruses “order” is defined as a group of virus ______ sharing certain ______ _________.
families, common characteristics
A viruses “family” is defined as a group of _____ sharing certain common characteristics with ____ _____.
genera, each other
A virus’ “sub-family” is defined as a group of genera sharing common characteristics and is used only when it is needed to solve a complex _______ problem.
hierarchical
A virus “genus” is defined as a group of ______ species that share some significant ______. Usually only differ in host _____ and _____.
related, properties, range, virulence
A virus “species” consists of a few words and must not consist only of a ?
host name.
Describe the physical properties of viruses
- Type of viral ____ ____
- The nucleic acid could be ______ ______ (ss) or ______ ______ (ds)
- viral ____
- ______ of viruses
- total number of _______ per virus
- presence or absence of the viral ______.
nucleic acid, single stranded, double stranded, size, symmetry, capsomeres, envelope
What are the two major chemical properties of viruses?
Heat sensitivity
pH sensitivity
Describe the biological properties of viruses
- Cytopathology (CP): specifically?
- Hemagluttination property
- Antigenic properties
site of replication (IC or IN), inclusion bodies
Inner core: is made up of _____ _____.
- Always occupy the _____ region of the virus
-Usually _______ to packed into a small space
-May be ______ _____ (ds) or _____ ______ (ss)
-ds: most of the ____ viruses; exception?
-ss: most ___ viruses; exception; exception?
-Sometimes segmented: examples?
Nucleic acids, central, coiled, double-stranded, single-stranded, DNA, Parvovirdae and Circovirdae (ss), RNA, Reoviridae and Birnavirdae (ds), Influenza viruses, Reovirues, and Birnaviruses
Outer membrane is made up of Viral ______
-Surrounds the ______ _____
-composed of ______ subunits called ______
capsids, nucleic acids, repeated, capsomeres
• Additional outer layer consists of Viral _____, ____
- _____-_____ layer acquired from the cell membrane of the _______ cells
- Usually covered with some projections called ________
- Non enveloped viruses are called ______ viruses
- Examples of enveloped viruses: ?
envelopes, peplos, Lipo-protein, infected, peplomers, naked, Coronaviridae, Influenza viruses
Viruses can be classified based on?
Nucleic Acids = DNA or RNA
Symmetry = Helical, Icosahedral, Complex
Envelope = Enveloped, Naked
The Capsid is the protein ____ surrounding the ____ _____. Capsomeres are the structural _______ of the _____.
Function of viral capsids
- Protects viral _____
- Serves as an ______ protein (only in the case of ______ /___-______ viruses) and bind the virus to susceptible _____ cells thereby promotes virus ____ into cells
- Stimulate the immune response to produce _______ against the virus
- Facilitates the ______ and _______ of the viral genetic materials.
shell, nucleic acid, subunits, capsid
genome, attachment, naked, non-enveloped, host, entry, antibodies, assembly, packaging
Helical symmetry viruses have:
-Capsomers arranged around the ____ ____ in a ______ fashion.
-Capsomers attached ______ to the helix of _____ _____.
-Most of the helical viruses are ______, and all are ____ viruses
-Examples: ?
nucleic acids, helical, directly, nucleic acids, enveloped, RNA, TMV
2- Icosahedral symmetry viruses or ____ have
-Capsomeres arranged around the _____ _____ in a ______ fashion
-Capsomers form a regular icosahedron composed of ___ ______ triangular facets
- Two types: _______ or ______ at vertices
- Examples: ?
cubic, Nucleic acids, icosahedral, 20, equilateral, pentagons, hexagons, Adenovirus, Picornavirus, Papovavirus, herpes
- 3- Complex symmetry viruses:
- ______, ______, _______, has a unique complex structure
Poxvirus, Bacteriophages, retroviruses
Label the image below
Naked icosahedral
The entire structure is a nucleocapsid
label on right = capsid
Label the image below
Naked helical
Label on left = capsid
Entire thing = nucleocapsid
Label the image below
Enveloped helical
Label the image below
Enveloped icosahedral
Label each of these accordingly
Capsomeres
Nucleic acid
Spikes/peplomers (glycoprotein)
Envelope (protein + lipid)
Identify the virus below
Rabies
Identify image below
Adenovirus
Identify the virus below
Influenza virus
Label the image below
Coronavirus
crown shape = spike glycoproteins
Identify the virus below
Ebola virus
The outer shell of the viral envelope surrounds the viral ______. The viral envelope itself is composed of a ____ _____ derived from the ____ cell membrane during the virus ____ from the cell and is composed of _______.
nucleocapsid, lipid bilayer, host, exit, glycoproteins
What are the functions of the viral envelope?
- Protects the viral nucleocapsid
- Mediates viral attachment and entry into host cells; HA in case of influenza viruses, spike in case of coronaviruses
- Mediates viral entry into the host cells
Enveloped viruses are sensitive to _____ ______ and common _______.
lipid solvents, disinfectants
Some viruses have projections called _____ or _______. Viruses may have one or more type of ______ (influenza virus, NDV, etc). Some viral peplomers have ____ function, while others have ____ or _____ functions. Give examples of each.
spikes, peplomers, peplomers, one, dual, multiple.
Example of virus with one function: HA peplomers in influenza viruses: Hemaagluttinations some RBCs.
Example of virus with dual function: HN peplomers in paramyxoviruses have two functions.
_______ causes elution of the agglutinated RBCs and facilitates the virus entry.
Neuraminidase
Some viral peplomers induce fusion of various cells together to form _______.
syncytium
Viral peplomers have some _________ properties.
antigenic
(+Ve) sense (Polarity)
Viral genome act as a ________ _______ (____)
Viral genome hook onto the _____ cell ______ directly then translated into _______.
messenger RNA, mRNA, host, ribosomes, proteins
(-Ve) sense (Polarity)
The genome must be transcribed into _______ copy before ______.
complementary, translation
All DNA viruses have ds genomes except?
Parvoviridae, circoviridae
All RNA viruses have SS genomes except?
Reoviridae, birnaviridae
Viral genetic materials function to:
1. Carries the ______ ______ for the progeny production
2. Codes for the synthesis of viral ______ required for viral _______.
3. Codes for the synthesis of viral ______ _____ required for viral assembly
genetic blueprint, enzymes, replication, structural proteins
(+Ve) Sense is a strand of viral ____ that can immediately serve as a template _____ for _____ synthesis during the process of ______. Examples are?
RNA, mRNA, protein, translation
Toga, corona, picorna, flavi
“Tuck christine’s panties, fanks!”
(-Ve) sense is defined as a strand of viral ____ that must first be converted into _______ _____ sense strands before creating _____. Examples are?
RNA, complementary positive, proteins
Mononegavirales (filo, borna, paramyxo, rhabdo, orthomyxo, arena, bunya).
Mom finds bunnies, parrots, rodents, octopi, and babies.
An ambisense is an ____ viral genome that is in part of ____ and in part of ____ polarity. Both nucleic acid strands encode _____. Examples are?
RNA, positive, negative, proteins
Arenavirus, phlebovirus, tospovirus, tenuivirus
Are puppies that tiny?
Some Physiochemical properties of viruses
______ pH: is optimum for the growth and multiplication of most viruses
Neutral
•Extreme ______ and ______: media are deleterious to most viruses
acidic, alkaline
•pH ___: is detrimental to most viruses
- Exception: ?
10
African swine fever virus (ASFV) – stable at pH 4-13
What products can be used to denature viral proteins?
1. _______ derivatives (_____)
2. ______ compounds (______)
3. Sodium ______ (____)/______ agent
4. Hydrogen ______/______ agent
5. _____ (mixture of _____ and surfactant) - ______ agent
Phenol, lysol, Ammonium, Roccal, hypochlorite, clorox, oxidizing, peroxide, oxidizing, Iodophors, iodine, oxidizing
How can viral proteins be inactivated?
You first soak the viral solution in 1 N NaOH and then autoclave it for 1.5 hours.
How can you denature both viral proteins and viral nucleic acids? Describe the mechanism of action.
Formaldehyde (1-5%), Glutaraldehyde (2%), Ethylene oxide (fumigation) - extremely toxic (must be in a sealed chamber), UV light (cross links the pyrimidine bases (C & T/U).
Mechanism of action: Incorporate short chain of carbon atoms to the viral proteins and NA leading to degradation.
How can viral envelopes be dissociated?
70% alcohol mixed with water results in lipid disruption and denaturing of proteins.
Baculoviruses: modified by genetic engineering to express some other viral proteins for _____ _____ as well as development of some novel ______ _____.
vaccine purposes, diagnostic assays
_____ and ______ used as viral vectors
Poxviruses, Adenoviruses
Lentiviruses: modified to insert some _____ ____ of interest into cells for _____ purposes and ______ ______.
foreign genes, research, gene therapy
Bacteriophages: used in the control of some _______ infections.
bacterial
Viruses specifically infect ______ and are obligate _______ parasites. Viruses infect various bacterial species, but most extensively investigated phages
infect ____ bacteria, ___ ____ and _______.
• Phages can be ____ or ____ and either _____ or _____-stranded.
• They have a _____ (head), a ____, and ____ fibers, which are _____. The
capsid has the ____. The tail fibers attach to the bacterial ____ _____ and inject the ____ into the cell.
bacteria, intracellular, enteric, E. coli, Salmonella, DNA, RNA, double, single, capsid, sheath, tail, contractile, DNA, cell surface, DNA
Label the image accordingly.
Green = head
Blue = collar
Purple = tail
Orange = tail pins
Yellow = end plate
Pink = tail fibers
Phages multiply by one of two
alternative mechanisms:
1. The Lytic Cycle: the host bacterial cell is ______ (_____ phages)
- The Lysogenic Cycle: host bacterial
cell remains _____ and _____. The life cycle results in a _____ genetic relationship with the _____. The phages are called ______ phages.
lysed, lytic, intact, alive, stable, host, temperate
Phage therapy is the therapeutic use of _____ bacteriophages to treat ________ infections
lytic, bacterial
Most phages are specific to _____ species of bacteria, and many are only able to lyse
specific _______ ______ a species. The limited host range can be advantageous, in principle, as phage therapy results in _____ _____ to the ______ body _____ and ecology than commonly used _______.
one, strains, within, less harm, normal, flora, antibiotics
Lytic phages are similar to ______ in that they have remarkable ______ activity. However, therapeutic phages have some advantages over antibiotics. Phages have been reported to be _____ effective than antibiotics in treating certain infections in humans and experimentally infected animals. List two examples.
antibiotics, antibacterial, more
Ex:1: Staphylococcal aureus phages were used to treat patients having the purulent disease
of the lungs and pleura
Ex: 2: Phages are used to reduce E. coli O157:H7 (a food-borne pathogen) on hide surface
of cattle before slaughter
• Bacteria can also develop resistance to phages
Describe the image below
Phages docking on a bacterium
Explain the image describing Koch’s postulates below
What does Koch’s postulates emphasize?
It is crucial to show that the virus is isolated from many animals that have the same disease.
What types of samples do you need to obtain for respiratory viruses?
Nasal, oropharyngeal swabs, fecal swabs, blood and serum.
What types of samples do you need to obtain for enteric viruses?
-Fecal swabs, feces, blood, serum in the live -Cattle (Rotavirus, Coronavirus, animals BVDV
-Parts from the organs of the digestive system such as intestine
Antemortem and postmortem
What types of samples do you need to obtain for vesicle-forming viruses?
-Vesicular fluids, saliva, blood, serum
What types of samples do you need to obtain for skin lesion producing viruses?
Scabs from different regions in the body
What types of samples do you need to obtain for nervous manifestations viruses?
- CSF, blood, sera, some brain tissues
Example of respiratory viruses
NDV, IBV, ILT in poultry
IBRV in cattle
Example of enteric viruses
Cattle (Rotavirus, Coronavirus, BVDV).
Example of vesicle forming viruses
FMDV, VSV, MCFV
Example of skin lesion producing viruses
Cow pox, camel pox, lumpy skin disease
Example of nervous manifestations
Rabies virus in animals
NDV in chicken
-Refrigerator temperature (4 °C): enough for the preservation of samples for ?
up to 24 hrs.
-Deep freezer temperature (-20 to -40°C): samples for ?
several weeks to a few month
Deep freezer (-80°C): enough to preserve samples for?
a few years
Liquid nitrogen (-196°C): enough to preserve samples for ?
many years
Lyophilization: (______ drying) as the viral suspension should be subjected to _____ pressure and ____ temperature, then the lyophilized material may store at ___ °C for a longer time.
freeze, high, low, 4
How do you process virology samples collected from body secretions and excretions?
• Body secretions or execrations in the form of liquids
-saliva, nasal swabs, -oropharyngeal swabs
1- Clarified by centrifugation at 3000 RPM
2- Supernatants should be collected and antimicrobial agents
-antibiotic cocktail (pensile and streptomycin) and -antifungal such as Fungizone should be added
to prevent any bacterial or fungal contamination tot eh virology samples
3- Samples should be stored at the appropriate temperatures until processed further
How do you process serum samples?
•The blood should be collected ________ adding any anticoagulants to obtain the _______.
•The tubes containing blood samples should be kept in ______ position at ___C for overnight or incubated at ___ C for ____ ____
•_________ of the tubes at 5000 rpm for ___ min
• ________ of the serum samples and transfer to new clean labeled tubes.
without, serum, oblique, -4, 37, 1 hr, Centrifugation, 10, Aspiration
Whole blood: collected on anticoagulants such as ______ or ______ _______ then subjected to low speed centrifugation at _____-______ rpm for 10 min
The blood will then separated into?
EDITA, sodium citrates, 1500-2000
-Plasma, Buffy coat : blood platelets and leukocytes and RBCs at the bottom
Usually viruses can be isolated from ?
the Buffy coat
PBMC = peripheral blood mononuclear cell
How do you process tissue specimens for virology diagnostics?
Parts from the target organs collected under aseptic conditions. About 1 gram of each organ should be excised by sterile clean scalpel or scissor.
The tissue pieces should be placed in a sterile mortar and
10 % tissue suspension should be prepared using 9 ml of PBS with the help of sterile sand . The obtained tissue suspension should subjected to three cycles of freezing and thawing Then to low speed centrifugation at 3000 rpm for 15 min at (4° C) Collection of the supernatant should be done and stored at (– 80 °C)
till use
