Viruses Flashcards
What’s a virus
A capsule with protien with genetic information
Why are viruses obligate parasites
Need a host to reproduce
4 key components of a virus
Genome
Capsid (protien)
Envelope
Enzymes
Not found in all viruses
Where does the virus get the envelope
Takes membrane from host cell
Function of enzyme for virus
Help manipulate cell
What are capsid made up of
Individual protiens and can be found in various shapes
What are spikes
Envelopes are generally host cell membranes with a few viral proteins stuck in. These viral proteins are called spikes
Helical capsid
A long tube of nucleic acids
Icosahedral capsid
Sort of a diamond shaped proteins, at the corners are where spike protiens are found
Bacteriophage
Bullet like capsule of protien at the top and then a stem
Used to introduce genes to bacteria
Envelope viruses
Look pouch like or round
Viruses can have genomes made up of either
RNA or DNA
If viruses intereste into the genome of the host what do they need to do
They have to create DNA to do that
It a virus needs to make proteins they need
RNA to do that
Retroviruses
RNA to DNA to RNA to protein
Can viruses sustain their own life
No
How does virus replicate
- Dock onto surface cell
- Enter cell
- Replicate
- Get out of cell
Docking
Protien spikes on outside of virus match receptors on cell
Receptors on HIV
CD4
CCR5
Some people don’t have CCR5 receptors so they are more resistant to HIV
Host range
Cell types and species that a virus can infect
Why can we get swine flu
We have similar receptors to pigs
Virus entry and uncoating
As the virus enters the cell it sheds the envelope
Goal of the virus during synthesis
Reproduce viral genome to package into new viruses
Make proteins for new capsid, spikes, etc
Method of viral synthesis
Virus is inside cell
Synthesizes new genome, new capsid protein, new spikes
Uses recourses from cell like viral ribosomes, hosts amino acids, other enzymes in order to reproduce
Asssemvly phase of virus
Mature virus particles are constructed from the growing pool of parts
Happens spontaneously and sloppily
Two ways assembled viruses leave their host
Non enveloped viruses reach maturation in the cell and are released when the cell ruptures
Enveloped viruses bud from the membranes of the cytoplasm nucleus endoppasmic reticulum or vesicles (cell doesn’t always have to die just buds off
Why does cell die with a virus
Virus steals so many of its nurturers so cell can’t survive
Syncytia
Cells may join together to make large multi nucleated cells to try and survive a virus (doesn’t work)
Why do some viruses cause cancer
Virus changes the way the cell reproduces (size function reproduction)
Persistent infections
Cells are converted to long lasting virus factories
Provirus
Viral DNA can be incorporated into the host genome
Latent virus
Virus can remain latent in host cell cytoplasm, waitin for an oppurtunity to break out and cause a new infection
I Covid used
Viruses that induce cellular reproduction
Bacteriophage
Virus that infects bacteria
Can carry genes from one bacterium to another
Common colds are most often caused by
Rhino virus
Or
Corona virus
Most antiviral drugs inhibit
One part of the life cycle (inhibitors, protease inhibitors)
Best medicine for viruses
Prevention and vaccines
Varicella zoster virus
Chicken pox
Varicella zoster virus come from what
Genital and and oral herpes
If Varicella zoster virus remains latent in the nerves then it can
Re-emerge in life in about 20% of patients which causes shingles
Why do viruses live in the nerves
They can just stay there because our bodies won’t destroy nerve cells
What’s used to treat shingles
Acyclovir
Complications of shingles
Can result in chronic nerve pain in the affected area
Dermatones
An area of skin served by a single peripheral nerve
Variola virus
Small pox
Variola virus symptoms
High fever, lesions appear first in mouth then everywhere, after 2 weeks lesions crust over, permanent scarring or death
What is the only completely eradicate disease so far
Small pox (variola virus) because of small pox
Rabies host range
Very wide r
Rabies transmission
Through saliva of animals
How does rabies virus move
Replicates at the site of the bite then moved up the nerves
Post exposure prophylaxis
One dose of human rabies immuno globin and rabies vaccine given on the day of the rabies exposure
HSV-1
Causes oral herpes or cold sores
Half people are estimated to have HSV one infection, sub clinical or otherwise
HSV-2
Causes genital herpes
Symptoms of Ebola
Flu like symptoms followed by vomiting diarrhea and rash. Advanced and deadly cases include organ failure bleeding from membranes bloody diarrhea vomit cough
Reston Ebola virus
Non pathogenic to humans though hazardous to some monkeys
Transmission of Ebola
First case of Ebola virus is believed to have been zoonotic passed from the blood meat or fluid from an infected animal
All the first vaccination efforts attributed to which virus
Small pox
Each outbreak of Ebola is a different…
Strain, with its own features
In order to infect cells HIV requires
Call receptors, rare dividual‘s are immune
HIV infections in the US in the 1980s led to adoption of what
Universal precautions in hospital settings including retractable needles
What is the main target for the HIV virus
Helper T cells, along with some macrophages, a few other cells in the body
Why are helper T cells targeted by HIV
Because helper T cells are required to drive other adaptive immune responses, when helper T cells levels decline, immune responses is crippled, including memory
To become infected with HIV you must be
Exposed to the virus and the virus must get to the lymph or blood rather quickly
What does it mean when we say HIV is not very resilient
It cannot live in surfaces or survive decontamination well. It also can’t survive on a living surface such as the skin for very long
Upon entry the HIV infection infects
Many T cells and macrophages
HIV uses macrophages as what
A Trojan horse to gain access to the T cells in lymph nodes
Intitial the viremia and a cute flu like symptoms result from what (HIV)
Infection of mucus producing tissue (especially G.I. tract, vaginal mucosa) occurs as well
Majority of HIV cells go into a ____. Infection
Latent so the patient is asympotmaric for months
Why is HIV a retrovirus
Transcribes it’s genome reversally
Long term non progressives
Effective immune response to HIV
AIDS
Fewer than 200 helper T CELLS
Get more opportunistic infections Cuz less T cells there to fight off
Berlin patient
Cured their own HIV
acute viral gastroenteritis
Rapid onset
Swelling
A description of symptoms basically saying the virus is causing these symptoms
Norovirus
RNA virus most common
Rotavirus
Gastrointestinal virus in children
But vaccine is available
Norovirus
Small infectious dose
Very hardy- can survive so fomites
Main risk is dehydration
Mumps
Viral infection of the salivary glands
Transmission of mumps
Spreads through infected saliva
Mumps virus enters the nose or mouth
Replicates in the upper respiratory tract
Releases in saliva almost a week before symptoms develop
Enters the bloodstream to infect salivary glands
Parotitis
Inflammation of the parotid salivary glands
IGMs are better for detection of mumps because
Can detect more quickly
Hepatitis
Swollen liver
Caused by many dif viruses
These viruses vary in viral family, epidimiology, what United them is they cause hepatitis
Mechanism of hepatitis
Hepatitis virus multiplies within intestinal cells
Virions enter the bloodstream
Inflammation develops and liver function is impaired
Bilirubin removal is limited
Causes yellowing of the skin
Sclera
Yellowing of skin
Hepatitis A
Single stranded RNA
Picornaviridae family
Transmission of hepatitis A
Viral particles are most concentrated in the feces two weeks before symptoms develops, remains infectious per month outside of the body, HAV is infected by high temperature
Hepatitis B
Double stranded enveloped DNA virus
Hepadnaviridae family
Transmission of hepatitis B
Direct contact with bodily fluid
Accidental through percutaneous exposures
HBV signs and symptoms
Can cause ache infection
Long incubation time
Cirrhosis
Caused by HBv
Hepatitis C
single stranded enveloped RNA virus
Flavivridae family
Transmission of HCV
Blood and bodily fluid
Vertical transmission
Why is HCV silent killer
Chronic symptoms usually not diagnosed until one ha serious liver problems
Hepatitis D and E
Concern in developing countries
Hepatitis D requires coinfection with
Hepatitis B to be transmitted, though not clear why
