Lecture 13 - Viruses, Viroids, & Prions Flashcards
inert
somewhere between living and dead - cannot replicate on their own
Because viruses must uses a host cell to replicate, they are considred _____ _____ _____.
Obligate Intracellular Parasites
In Latin, VIRUS means:
poison
morbidity
sickness
mortality
death
virology
the study of viruses
What type of bactiera looks like a little spaceship?
Bacteriophage
What shape does Ebola Virus look like?
looks like a worm
What is the genetic material found in viruses?
DNA or RNA
(never both simultaneously)
*can be single-stranded or double stranded
Is influenza an RNA or DNA virus?
RNA
Microscope Used to View Viruses
Electron Microscope
(because most viruses are smaller than 200 nanometers)
Capsid
protein coat surrounding a virus’ nucleic acid
Capsomere
an individual protein in the capsid
Diffrence between a Naked and and Enveloped Virus
An Enveloped Virus has an extra liipid covering (envelope) surrounding the capsid whereas a Naked Virus has no envelop surrounding the capsid.
Outtermost Layer of a Naked Virus
Capsid
Outtermost Layer of an Enveloped Virus
the Envelope
Spike Proteins
found on the envelope of viruses and can help the virus enter/infect other cells
Is Herpes Simplex Virus (HSV) Naked or Enveloped?
enveloped
Chicken Pox AKA
Varicella Zoster Virus
Is Chicken Pox (VZV) Naked or Enveloped?
Enveloped
Is Mononucleosis Naked or Enveloped?
Enveloped
Is West Nile Virus Naked or Enveloped?
Enveloped
Is Hep C Naked or Enveloped?
Enveloped
Is Influenza Virus Naked or Enveloped?
Enveloped
Are Measles and Mumps Naked or Enveloped?
Enveloped
Is Rabies Virus Naked or Enveloped?
Enveloped
Is HIV Naked or Enveloped?
Enveloped
Is the morphology of a virus based off of its envelope, capsid, or outermost layer?
Capsid
Why is COVID-19 called a Corona Virus
because the spike proteins look like a crown around it in the microscope
Ebola Virus Capsid Morphology
Helical
Rabies Virus Capsid Morphology
Helical
Influenza Virus Capsid Morphology
Helical
Icosahedrons
Polyhedral Virus with 20 sides
West Nile Virus Capsid Morphology
Icosahedron
(Polyhedral)
Norovirus Capsid Morphology
Icosahedron
(Polyhedral)
Adenovirus Capsid Morphology
Icosahedron
(Polyhedral)
Polio Capsid Morphology
Icosahedron
(Polyhedral)
Zike Virus Capsid Morphology
Icosahedron
(Polyhedral)
Stomach Flu AKA
Norovirus
(*NOT the same as Influenza Virus)
Norovirus often causes ______.
Gastroenteritis
(stomach flu)
Example of Complex Virus Morphology
Bacteriaphage
Is Chicken Pox Virus a Pox Virus?
No.
It is a type of Herpes Virus (Varicella Zoster Virus)
What are 2 examples of Pox Viruses?
Cow Pox
Small Pox
Why is it difficult to develop antiviral drugs?
It is hard to develop drugs that will attack the virus without damaging our cells because viruses use our cells and machinery as a host.
5 Steps of Viral Replication
1 - Adsorption (attachment of virus to host cell)
2 - Penetration or Entry of Nucleic Acid or Capsid into Host Cell
3 - Uncoating (removal of capsid surrounding nucleic acid)
4 - Biosynthesis
5 - Release
Adsorption
attachment of a virus to the host cell
Uncoating
removal of capsid surrounding nucleic acid
Biosynthesis
replication of the viral genome using the host cell
Two Methods of Release at the End of Viral Replication
- Budding
- Lysis
How do viruses find a host cell?
a spike protein on the virus will bind to a receptor on the host cell
Describe the Lytic Replication Cycle of a Bacterial Virus
1- Attachment of Virus to the Bacteria
2- Penetration of Phage DNA into Bacteria & degradation of host DNA
3- Synthesis of Viral Genome & Proteins
4- Assembly of New Viruses
5- Lysis/Release of New Viruses
Difference between the Lytic Cycle and Lysogenic Cycle
In the Lytic Cycle, phage DNA enters the bacteria and immediately begins synthesizing new viruses until the cell lyses to release the new viruses.
In the Lysogenic Cycle, phage DNA may be incorporated into the bacterial DNA and the bacteria may replicate so the daughter cells also have the prophage (viral DNA).
*The prophage may exit the bacterial DNA and then enter the Lytic Cycle.
Discovered the Lambda Phage which can enter the Lysogenic Cycle
Esther Lederberg
prophage
viral DNA inserted into a bacterial chromosome
Why was the discovery of lysogenic cycles so important?
Many pathogenic bacterias are as pathogenic as they are because phage DNA has been incorporated in their DNA. This phage DNA gives the bacteria additional triats such as the ability to produce certain toxins that it would create otherwise.
Why are some bacteria highly pathogenic?
They contain prophages which encodes for toxins
Describe the difference between the proliferation of a DNA vs an RNA Virus
DNA Viruses require tht that the viral DNA be replicated, transcribed and translated.
Meanwhile, RNA Viruses can be replicated by viral proteins and immediately translated
What type of virus is HIV?
Retrovirus
HIV
Human Immunodeficiency Virus
Describe how a Retrovirus Functions
- Viral RNA and Viral Reversetranscriptase enzyme enter the host cell.
- The reverse transcriptase can then transcribe the RNA into double stranded DNA which can enter the nucleus and insert itself into the chromosome
Provirus
viral DNA inserted into eukaryotic DNA following reverse transcription of viral RNA
What is plaque in terms of studying viruses in the lab?
Plaques are the dark circles on the petri dish where the host bacteria has been lysed
in vitro
“within the glass”
in vivo
“within the living”
Name 3 Types of Cell Lines
Primary
Diploid
Continuous
Corynebacterium diptheriae causes
Diptheria
Causes Scarlet Fever
Streptococcus pyogenes
Causes Cholera
Vibrio cholerae
Toxin Encoded by prophage in Corynebacterium
Diptheria Toxin
Toxin Encoded by Prophage in Streptococcus pyogenes
Erythrogenic Toxin
Causes Botulism
Clostridium botulinum
Toxin Encoded by Prophage in Clostridium botulinum
Botulinum Toxin
Toxin Encoded by Prophage in Vibrio cholerae
Cholera Toxin
How do Naked Viruses typically enter an animal host cell?
Endocytosis
How do Enveloped Viruses typically enter an animal host cell?
Membrane Fussion
2 Ways Naked Viruses are Released from the Host Cell
Lysis
Exocytosis
How are Enveloped Viruses Released from the Host Cell?
Budding
Central Dogma
DNA –> RNA –> Proteins
virus which often causes colds and upper respiratory infections
Adenovirus
In America, are you more likely to get sick with a virus or a bacterial infection?
virus
What are HeLa Cells?
HeLa cells are cells from a continuous cell line from Henrietta Lacks who died of cervical cancer around 1951
CPE
Cytopathic Effects
List some examples of Cytopathic Effect (CPE)
- cells are enlarged, granular or missing due to viral infection
- presence of inclusion bodies
- presence of syncytia
Negri bodies
inclusion bodies found in people infected with rabies
Syncythia
mutiple hosts cells fuse together to form a giant multinucleated cell
-ase
an enzyme
3 Non-Microscopy Methods to Detect Viruses
- PCR
- FA Technique
- Serology (i.e. ELISA or Western Blotting)
The “FA” in FA Technique means
Fluorescent Antibody
RT-PCR
Reverse Transcrptase Polymerase Chain Reaction
What is RT-PCR used for?
used to test for genetic material of RNA Viruses
Antibodies bind to ______.
Antigens
antigen
a molecule that an antibody can specifically bind to
How many binding sites does an antibody have?
2
Oncogenic Viruses
viruses that can cause cancer
CA
cancer
HBV
Hepatitis B Virus
EBV
Epstein Barr Virus
HPV
Human Papilloma Virus
Which Virus can cause Liver Cancer?
HBV (Hepatitis B Virus)
Epstein Barr Virus AKA
Mononucleosis or Mono
Human Papilloma Virus AKA
Genital Warts
Which Virus can cause Burkitt’s Lymphoma?
EBV (Epstein Barr Virus)
Which Virus can cause nasopharyngeal cancer?
EBV (Epstein Barr Virus)
Which Virus can cause cervical, penile, uterine, or anal cancer?
HPV (Human Papilloma Virus)
Is early vaccination against STDs correlated with people having sex at younger and younger ages?
No
VZV
Varicella Zoster Virus
(AKA Chicken Pox)
________ is a reactivation of VZV.
Shingles
One who had chicken pox as a child has a ___% chance of developing _________ as an older adult.
10% chance of developing shingles
What is Shingrix?
an effective vaccine against shingles which can be administered around age 50
Shingles is considered a ______ _____ becuase it is a reactivation of VZV long after it was originally acquired.
Latent Virus
HHV-1 and HHV-2 are also known as
Herpes Simplex Virus
Is Type 1 Herpes Simplex Virus generally associated with Cold Sores or Genital Sores?
Cold Sores
Is Type 2 Herpes Simplex Virus generally associated with Cold Sores or Genital Sores?
Genital Sores
Because Herpes Virus can reappear after long period of no symptoms, it is known as a _____ _____.
Latent Virus
Rubeola AKA
measles
Rubella AKA
German Measles
What is the difference between Rubella and Rubeola?
Koplik’s spots are generally associated with Rubeola (measles) whereas it is not associated with Rubella (German Measles) and Rubella is generally more mild.
MMR Vaccine protects against which 3 viruses?
Measles
Mumps
Rubella
Herd Immunity
if enough people are vaccinated against a pathogen, people who are unvaccinated can still experience protection because the liklihood of people around them being infected is decreaed
Generally approximately at least ___% of a population needs to be vaccinated for herd immunity to be effective
80%
Approximately how long does it take before a vaccination received is effective?
2 weeks
What’s the best effectiveness you can hope for from a flu vaccine each year?
~ 60%
“SARS” in SARS-CoV-19 stands for
Severe Acute Respiratory Syndrome
“MERS” in MERS-CoV-2 stands for
Middle East Respiratory
Viroid
circular RNA that has bonded to itself in various area to creat areas of double and single strandedness
What is the only human disease caused by a viroid?
Hepatitis D
Prions
proteins that can reproudce on their own and become infectious when misfolded
Where in the body are prion proteins found?
in the brain
TSE
Transmissible Spongiform Encephalopathy
When misfolded prions stick together they can form ______ _____.
amyloid fibers
What type of cells eliminate dead neurons?
astrocytes
Oncogenic
Cancer-Producing