micro final cards p. 2 (food/waterborne bacterial diseases, viruses, and prions)

what type of transmission is food/waterborne illness?

it is vehicle transmission, specifically indirect

what introduces the pathogen in food/waterborne illness?

ingestion

illnesses of food/waterborne disease is caused by what? (2)

intoxication or infection

between intoxication and infection, which has a shorter incubation period?

intoxication

are exo or endotoxins able to be denatured?

exotoxins can be denatured

what does an infection need to do to complete infection and incubate?

the organism needs to get to the target tissue meaning it has to get through the stomach

why do viruses NEED a living host to replicate?

they use the synthesizing machinery in the cell

what classification of parasite is a virus?

obligate intracellular parasite

what microscope is used to view a virus?

electron microscope

how many nucleotides do viruses contain for their small genomes?

10³-10⁵ nucleotides

how is a virus differed from bacteria? (name what bacteria have that virus don’t)

bacteria all have the ability for binary fission, has both DNA and RNA, has ribosomes, and has abx sensitivity

describe the components of a viral genome

either DNA or RNA. either ss, ds, linear, segmented, or circular

what do all viruses have to contain their genome?

a capsid

define capsid composition

made of protein, and has 3 common shapes which are icosahedral (20 equilateral triangles), helical, and complex

what is the name for a repeated capsid unit

capsomere

describe envelope composition for a virus

it is a lipid membrane with glycoproteins (spike proteins)

what do DNA viruses and the host cell both have?

the same genetic material

where do DNA viruses get RNA pol to make more viral mRNA?

from the host cell

since the pox virus doesn’t go into the nucleus, what does it need to carry with it to replicate?

pox viruses need to carry their own RNA pol to replicate

what do ssDNA viruses need to make for viral mRNA synthesis?

they need a second strand of DNA

what is special about retroviruses that other viruses cant do?

they go against the central dogma meaning they can make their RNA into DNA and trick the host cells into making copies of it

why do viruses want to make mRNA? (what translates mRNA)

the host virus translated the mRNA into viral proteins for more viruses

does viral mRNA need to be negative or positive sense before translation?

positive sense RNA

if a virus has neg sense RNA, what does it need to change the negative to pos sense RNA?

it needs an RNA-dependent RNA polymerase

how do RNA viruses go against the central dogma? (include retroviruses)

RNA in RNA viruses will either already resemble mRNA and is immediately translated or it gets transcribed into mRNA or, with retroviruses, gets RT’d into DNA and integrates into the host genome

what is the central dogma?

DNA —(transcription)> RNA —(translation)> protein

do DNA or RNA genomes mutate more? why?

RNA genomes mutate more because they have little to no proofreading measures compared to DNA

order the mutation rate from highest to lowest with ssDNA, RNA, dsDNA, viroids, bacteria, higher euk, and lower euk

1. viroids

2. RNA

3. ssDNA

4. dsDNA

5. bacteria

6. lower euk

7. higher euk

does a bigger or smaller genome mean more mutations?

bigger genome

what is the family name for viruses? genus?

family = -viridae

genus = -virus

do virus have species?

no they dont

what part of a virus determines its host range and specificity?

the virus structure determines it

do viruses have a wide or narrow host range? (humans and others or just humans)

viruses tend to have narrow host ranges

what is the tissue tropism of a virus determined by? (2)

the cell receptor that allows for virus entry and the virality of the virus meaning whether it’s enveloped or not

what does Poliovirus have to help it attach to the cell receptors?

it has capsid proteins to help attach

if the virus has spike/glycoproteins, is it enveloped or non-enveloped?

it is enveloped

how do animal viruses attach to cells?

animal viruses attach to the host plasma membrane via entry proteins on the capsid or spikes on the envelope

for enveloped viruses, how do they enter cells?

through fusion. the spikes on the envelope attack to the membrane and the membrane then fuses with the virus envelope membrane and the capsid can freely move into the cell

does endocytosis allow for only non-enveloped viruses to enter?

no, both type of viruses can enter

describe endocytosis entering

the viral protein has viral proteins outside the capsid which bind to receptors on the host cell membrane. the receptors then tell the cell to “eat” the capsid and once the vesicle is inside, it releases the capsid into the cell

why is RNA dependent, RNA pol so important for both pos and neg sense RNA viruses

pos sense RNA needs it for replication and neg sense RNA need it for both replication and to become pos sense RNA

what are the multiple ways of a virus damaging a host through cytopathic effects?

syncytia, inclusion bodies, cells killed by immune system, apoptosis

what are the inclusion bodies for rabies called?

Negri bodies

describe syncytia

this is when the virus cause multiple cells to stick together to let the virus move across the cells and dodge the immune system

describe inclusion bodies

these are proteins that act as compartments to both trap immune system proteins and enhance viral replication

how can viruses cause the immune system to attack the host

tissue infected by a virus can cause CD8+ T cells and NK cells to kill too much of the tissue and cause damage. viruses can also causes cytokine storms

describe how apoptosis is a viral CPE

cells can kill themselves to stop the spread of a virus but sometimes too many cells will die and the host is more vulnerable

what is the percentage of virus associated human cancer?

20% of human cancers

what part of the body does cervical cancer refer to?

the cervix

what cancer is most prevalent in women? men?

women is cervical and men is liver cancer

list the causal relationships (4)

sufficient, necessary, sufficient and necessary, contributory

name the example related to smoking for sufficient causality

if smoking were sufficient to cause lung cancer, then everyone who smoked would get lung cancer

name the example related to smoking for necessary causality

if smoking was necessary for lung cancer, only those who smoked would have lung cancer

name the example related to smoking for sufficient and necessary causality

if smoking were sufficient and necessary, everyone who smoked and only those who smoked would get lung cancer

name the example related to smoking for contributory causality

if smoking was contributory, smokers would have higher chances of lung cancer

what 6 viruses contribute to human cancer?

• hepatitis B virus

• hepatitis C virus

• Human Papillomavirus

• Epstein-Barr virus

• Kaposi’s sarcoma-associated herpesvirus

• human T-lymphotropic virus type 1 and 2

what is the causality of HPV?

it is necessary but not sufficient for cervical cancer

how do viruses contribute cancer? (3)

1. the virus has a viral oncogene that pushes the cell through mitosis more

2. the virus can insert into the genome of the cell thus deregulating mitosis from mutations

3. the viral infection can increase tissue inflammation which is a known feature of tumors

regarding viral tissue inflammation and cancer correlation, how does that work with chronic hepatitis C virus?

the liver cells of the patient are damages so mitosis will begin for liver stem cells in the inflammation zone. these cells will then go through respiratory bursts due to _____ which then causes the stimulation of cell growth to grow more

what do antiviral agents target to control viruses?

usually target a component of the viral replication cycle

what do Tamiflu and Relenza inhibit and what is that used for in influenza?

they both inhibit Neuraminidase which is an influenza glycoprotein used to exit the infected cell

why do Tamiflu and Relenza choose to inhibit specifically the Neuraminidase glycoprotein?

Neuraminidase is proprietary to the influenza virus so it is guaranteed to target influenza

what is a prion?

it is a protein-only infectious agent

describe a prion (size, genome [y/n], how it’s transmitted, what does it infect)

it is extremely small, does not have a genome, transmitted via ingestion or iatrogenically, and infects the brain

can prions spontaneously form? why?

yes, they can because they are essentially proteins that can corrupt other normal proteins. some specific proteins in mammals can mutate and misfold into prions

describe the Scrapie prion

this is a disease found in goats and sheep which causes them to rub themselves on things so hard they would scraping themselves. this prion causes spongiform encephalopathy in the CNS

what is spongiform encephalopathy?

this is when there are large empty vacuoles in neurons. threadlike fibers form amyloid plaques. there is no inflammation

what is the mad cow disease?

this is spongiform encephalopathy in cows or bovine spongiform encephalopathy (BSE). it was seen in the UL mainly and was suspected to have been transmitted to cows from feeding ground up infected sheep bone

who discovered BSE was a protein? how?

Stanley Pruisner found this out. He did this by exposing infected cow samples to numerous DNA damaging agents and found that only protein denaturants made the sample non infectious.

what do prions cause?

transmissible spongiform encephalopathies or TSE’s

what is the human infectious version of a TSE?

variant Creutzfeldt-Jakob disease (vCJD)

what is the human inherited version of a TSE?

CJD (no “v”)

what prions convert normal proteins to prions? PrPSc, PrPC, PrPS, PrPiC

PrPSC (Sc like scrapie)