Viruses and Prions Flashcards
What is a host range ?
range of several animal species & tissue cells that virus can infect
- can be broad or limited
What is a capsomere ?
morphological subunits from which virus capsid is built
What is a capsid ?
protein shell or coat that encloses nucleic acid genome
- outer shell that contains the genetic material inside of it
What is the envelope ?
lipid-containing membrane that surrounds some viruses
What is a nucleocapsid ?
capsid together w/enclosed nucleic acid
What is a virion ?
complete infective virus particle
- fully formed virus
What is a incomplete virion ?
virion without nucleic acid
- empty capsid
- doesn’t have genetic material
What is a pseudovirion ?
when the capsid has enclosed genetic material from the host cell instead of the genetic material from the virus
- a mistake
- looks like ordinary virus but it doesn’t replicate
What is a provirus ?
viral DNA that is integrated into host cell chromosome in latent state and must be activated before it is transcribed
- leading to production of progeny virions
- transmissible from parent cell to daughter cell
What is the size of the smallest, largest, and E.Coli viruses ?
- smallest: 20 nm
- largest: 300nm
- E.Coli: 1000nm
What are some general characteristics of viruses ?
- contain either DNA or RNA (never both)
- lack cellular components necessary to generate energy and synthesize proteins
- contain few enzymes
- contain a minimum amount of genetic information
What do most DNA viruses contain ?
contain all their genetic information in a single linear molecule
- can be either single or double stranded
What do most RNA viruses contain ?
can be linear or contain segmented genomes which have several different RNA molecules in their capsid
- each one carrying the same or different genetic information
- can be either single or double stranded
Since viruses have few enzymes what can they do ?
only those involved with entry into cells can replication of their own nucleic acid
- can only multiply inside living cells
How much genetic information do viruses contain ?
contain the bare minimum of their genetic information
- info to make its special protein coat
- info to assure replication of its own chromosome
- info to move the virions in and out of host cell
What determines the shape of the virus ?
the shape of the capsid
- helical or spherical
- each capsid is composed of many identical units (capsomeres)
With the tobacco mosaic virus how can you transmit it ?
if you garden and smoke you can easily transmit the virus to peppers
How do the viruses that have a envelope (lipid membrane) acquire it ?
from cytoplasmic membrane of infected cell
What are some characteristics of viruses with a envelope ?
- structure is similar
- double layer of lipids
- inside the lipid envelope is protein matrix
- spikes project from the envelope and attach the virion to host cell (protein and glycoprotein)
What are some diseases caused by DNA viruses ?
- hepatitis B virus
- gastroenteritis
- HPV
- HSV
- smallpox
What are some diseases caused by RNA viruses ?
- influenza
- zika
- SARS
- ebola
- AIDS
- hantavirus
- rabies
- measles, mumps
- rubella
- pollo, hep A
- rotavirus
- California encephalitis
- dengue fever
In pregnant women, what can zika virus cause ?
can cause microcephaly in their children
What are some S&S of Zika ?
- HA
- pain behind eyes
- fever
- vomiting
- skin rash
- muscle and joint pain
- conjunctivitis
- 1 out of 4 develop symptoms
- symptoms last 1 week
What are the 4 ways of diagnosing viral infections ?
- cell culture
- serological techniques
- direct detection of antigen from specimen
- molecular methods
What is a cell culture diagnosis ?
- living cells
- Ex.) chick embryos
What is a serological technique diagnosis ?
detecting antigen and antibodies
What is a direct detection of antigen from specimen diagnosis ?
polymerase chain reaction (PCR)
What is a molecular method diagnosis ?
live or dead viruses
What are some viral specimen types ?
- upper respiratory: swabs, nasal, throat
- lower respiratory: endo trach aspirations, lung and bronchial biopsies
- eye swabs
- stool/rectal swabs
- body fluids (bone marrow, serum, blood saliva)
What are some characteristics for collection and storage of viral specimens ?
- isolation and direct detection must be collected within the first few days of onset of illness
- specimen should not be held at ambient temp (delivered to lab on ice and store at 4-8 C for not more then 1-3 days before excessive loss of infectivity)
- freezing at -70C or below will preserve indefinitely
- refrigerator freezer back and forth will cause loss of infectivity rapidly because of temp recycling
What are some characteristics of Ebola ?
- helical wavy type virus
- RNA virus
- very fatal
- transmitted through bodily fluids
- 25-90% fatality depending on the strain (not all are as deadly as others)
- symptoms in the early stage are like many viruses and then it gets worse
- don’t have Ebola in the USA because its not as easily passed on from person to person (more body fluid spread)
What are some early symptoms of Ebola ?
- HA
- muscle pain
- sore throat
- fever
- fatigue
What are some late symptoms of Ebola ?
- bleeding from eyes, nose and mouth
- impaired liver and kidney
- D &V
- rash
- internal and external bleeding
What are some preventative measures for Ebola ?
- stop contact with infected animals and the consumption of their meat
- isolate the sick
- prompt disposal of victims’ bodies
- disinfect homes of dead and infected
- protective clothing for healthcare workers
What are the normal function of Helper T cells ?
- activate B cells that produce antibodies
- activate Killer T cells that destroy infected cells
Why is HIV dangerous ?
it affects the immune system
- without Helper T cells functioning properly, you can’t fight off pathogens that can make you sick
- people with AIDS die of 2ndary infections because their immune system can’t fight the infection (don’t die from AIDs itself)
What is the primary host animal for Ebola ?
bats
- earlier case is where a child was playing in a cave with bats
How is Ebola transmitted in traditional funeral practices ?
- you lay your hands on the dead body
- with unprotected healthcare workers they don’t know they are interacting with an Ebola pt because its in the early stages
What is the Hot Zone (Ebola) ?
- In a monkey facility they were dying and people didn’t know why
- people were flying in to try to figure out what was going on and then leaving back onto the planes and flying back to where they came from
- it was found to be a form of Ebola
- they were lucky because this strain only killed monkeys and not humans
- human could pick it up but won’t die from it
What are some characteristics of SARS ?
severe acute respiratory syndrome
- caused by SARS coronavirus
- outbreak in China
- no cases since 2004
- we able to stop it quickly because they isolated people quickly
- not as infectious as COVID
What are some symptoms of SARS ?
- flu like (fever, lethargy, myalgia (muscle tenderness), cough)
- fever above 100.4F was only symptoms all pt’s had in common
- chest x-rays show atypical pneumonia
What is COVID ?
contagious respiratory disease that was first detected in China in December 2019
- the 2019 new coronavirus is called SARS-CoV-2 and the disease it causes is coronavirus 2019 which is COVID-19
Why was COVID a bigger problem then previous coronaviruses ?
- it’s easily transmissible and can spread quickly from person to person
- carried on respiratory droplets and can land on surfaces or in someone’s mouth/nose
- 6 feet is the distance it keep for droplets (the distance it can travel)
- need good hand hygiene
What is the main difference between the Pfizer/Moderna and the JJ vaccine ?
- Pfizer/Moderna are mRNA vaccines
- JJ is a viral vector
How does the Pfizer and Moderna vaccine works ?
use mRNA to deliver instructions to our body’s cells
- that teach it to produce the spike protein found on the surface of the COVID virus and then the mRNA goes away and now the proteins in your body know how COVID looks like and can fight it off
How does the JJ vaccine vaccine work ?
uses a virus (vector) to deliver instructions to our body’s cells
- uses genetic material from the COVID virus and inserts that into the weakened virus and then your cells make the protein or antigens that will be recognized by your immune system which can then recognize COVID
What are the age ranges for each COVID vaccine ?
- Pfizer: 16 and older
- Moderna: 18 and older
- JJ: 18 and older
What are the # of doses for each COVID vaccine ?
- Pfizer: 2 doses taken 21 days or 3 weeks apart
- Moderna: 2 doses taken 28 days or 4 weeks apart
- JJ: 1 dose
When are you fully vaccinated for COVID with each vaccine ?
- Pfizer/Moderna: 2 weeks after second dose
- JJ: 2 weeks after initial dose
What is a prion ?
an infectious protein that can trigger normal proteins in the brain to fold abnormally
- doesn’t have genetic material
- not a virus
What is a viroids ?
has genetic material and a protein
What is prion theory ?
these infectious proteins when they develop will touch others and change those proteins into another infectious protein
- kind of like in the Walking Dead in how Zombies will bite someone and turn them into a zombie
- these infectious proteins won’t act as they usually do
Who do prion diseases affect ?
both humans and animals are affected
- sometimes spread to humans by infected meat products
What is Bovine Spongiform Encephalopathy ?
a chronic degenerative disease affecting the CNS of cattle that causes the brain and nerve cells to die
- commonly called “mad cow disease”
- cooking the meat doesn’t kill the prions
- Britain was the worst out of them all
- USA only had 22 cases
- banning feeding cattle nervous tissue and bones fixed the problem
Are prions curable ?
prions are always fatal and there is no cure
- you will die
How was Bovine Spongiform Encephalopathy a problem in Europe ?
when animals were slaughtered, the bones and nervous tissue that were left over were ground up and was put into cattle feed to be fed back to cows
- you could have started with 1 infected cow and then you ground the leftovers and feed it to hundreds other cows and the infected numbers grow
What is Chronic Wasting Disease (CWD) ?
impacts brain tissue of deer
- people would track deer in one part of the country and them trap them and enclose them in another part of the country where it wasn’t introduced yet
- then it infects the wildlife and other deer
What are some prions in humans ?
- Creutzfeldt Jakob Disease (CJD)
- Variant Creutzfeldt Jakob Disease (vCJD)
- Gertmann Straussler Scheinker Syndrome
- Fatal Familial Insomnia
- Kuru
What is Creutzfeldt-Jakob Disease (CJD) ?
a disease caused by abnormal proteins that are not killed by standard methods for sterilizing surgical equipment
- as the brain slowly shrinks and the tissue fills with holes until it resembles a sponge
What are some consequences of CJD ?
those affected lose the ability to think and move properly and suffer from memory loss
- is always fatal, usually within 1 yr of onset of illness
What are some characteristics of Sporadic/Classical CJD ?
cause is unknown
- affects mainly over 50s
- S&S: dementia, spongiform changes, rarely plaques, short course, ataxia (loss of control of body movements)
What are some characteristics of Familial/Infectious CJD ?
caused by inherited mutation in the PrP gene
- younger age of onset than sCJD, longer course
- similar to sCJD,
What are some characteristics of Iatrogenic CJD ?
caused by contamination during brain surgery, corneal transplant, dura mater grafts
- age dependent on the exposure source
- clinical and pathologic symptoms indistinguishable from sCJD ?
What are some characteristics of Variant CJD ?
caused by exposure to Bovine Spongiform Encephalopathy (BSE)
- younger age of onset, longer duration of symptoms
- distinctive daisy plaques seen. psychiatric signs present
What is Kuru ?
a prion that was identified through research done by Robert and Louise Glasse in the 1950’s in New Guinea
- mostly women and children were affect; few adult males
- 1% of Fore tribe was afflicted
- evidence led the Glasses to suggest that endocannibalism was associated with disease
- the hypothesis was not well accepted among medical community
What are some symptoms of Kuru ?
- HA
- joint pain
- then 6-12 weeks later
- difficulty walking then death usually within 12 months, always within 2 years
What is the life span of someone who has Kuru ?
death usually within 12 months
- always within 2 yrs
Why were women and children primarily affected by Kuru ?
in the Fore tribe as a part of the funeral services they would eat their loved ones after they died
- women and children tended to get the nervous tissue and adult men mostly didn’t eat the nervous tissue
What are virioids ?
only made up of genetic material (SS RNA)
- no protein coat
- only a little larger then prions
- mainly in plants
- spread through contact between plants
