Ch 21: Viral Replication

how can HHV2 affect babies?

*remember HHV2 is genital herpes..* -so, it can make a baby blind when it comes out of the vagina... cold sores infect the eyes and make blind.. -can infect their brain also.

what happens when the virus stays in permanent lysogen?

- -remember that in lysogenic phase.. the virus's DNA is incorporated in the bacteria's genome.. -eventually the bacteria no se da cuenta que es DNA de virus entonces it uses it. -bacteria uses DNA genes and may accidentally help the bacteria. -the virus doesnt mind this bc they want the bacteria to be happy/ more fit to survive/more toxic. *this happens bc the virus wants the bacteria to be happy and healthy bc if bacteria is more stable= will wake up and go into lytic cycle* - a lot of bacteria are deadly bc it has a toxic virus inside that makes it more strong.

transduction

- a way in how a virus can shape bacterial evolution. -it moves DNA form one bacteria to another.

what is Transformative ?

- when the virus causes cancer

what are the lytic cycle's 7 steps?

-Attachment -Entry -Uncoating -Gene Expression -Genome Replication -Assembly -Egress -Maturation (maybe.. not all viruses do this)

nothing happens in latency cycle.. but one mRNA is actually transcribed.. which one is it? what mRNA is transcribed in latency?

-LAT -it is a mRNA that keeps the virus asleep byu preventing the virus from doing anything.. inhibits gene expression, etc. -it also keeps the cell alive (by stopping it from killing itself.) while it still sleeps/chills.

how does Lysogenic cycle come about?

-So, example (look at picture): -A bacteriophage infects a bacteria by inserting its DNA (in red) inside the bacteria. After the DNA is inserted, there are two options: 1. virus can go into lytic cycle (and makes more viruses) OR 2. Can go into lysogenic infection (so, doesnt make new viruses) -during in lysogenic infection, the virus' DNA is inserted into the bacteria's genome. ------------------- -eventually it will go back into the lytic cycle. OR can stay in permanent lysogenic cycle and permanent inactive.

HHV3 latency

-after the rash is gone, the virus travels into nerves around the skin... it travels into the nerve and into the spinal column -it stays there the rest of your life. -may be dormant or can wake up

how do you prevent HHV1 in the first place?

-avoid contact w/ infected ppl. -the bad thing is that you are considered contageous at least a day before you get the cold sore so, they may contagir ppl without knowing it at first.

how can you prevent HHV2?

-avoid ppl who are infected -condoms -C-sections for babies (for them not to go blind)

HHV8

-causes Kaposi's sarcoma -it causes dark bumpy lesions (dark bumps) -disease most common in HIV patients. -one of the indications that someone has HIV (it was the stigma) -causes cancer -not as common

what happens when chicken pox is "woken up"

-chicken pox that wakes up from latent stage evolves to SHINGLES. -if it wakes up in the spine, it picks a nerve (any nerve in the spine).. travel up to the skin and cause infection only where that nerve connects. -it is highly concentrated in an area because it travels to the skin via a nerve! (not like the blood like chicken pox)

HHV2/HSV2

-cold sores in the genitals. --same as HHV1 just in another part of the body. -it is transmitted through: sexual contact, skin to skin contact w/ infection -lifelong infection! once u have it, u have it... but goes latent.

HHV5

-doesnt cause disease in healthy people -it affects pregnant women or HIV

latency

-dormant phase (not replicating)

how is chicken pox correlated with age?

-if you get chix pox for the first time and youre older... it may be worse for you! -the younger you get it at first, the better.

shingles

-it always starts with chicken pox!!! -the virus is highly concentrated in an area because it travels to the skin via a nerve! (not like the blood like chicken pox) symptoms: skin itches, hurts.. pain so bad you may not be able to put clothes on -this may last for weeks. -the reactivation has to do with stress/ immunocompromised. -shingles is contagious.. you have to get the virus into nose/eyes... not respiratory like chicken pox.

mono

-it is a lifelong virus.. it will have a latent state in the B cells of the body.

lysogenic cycle

-it is a type of latency but it is not fully "frozen" -while in latent phase, it integrates part of its genome into host cells.

when is Lysogenic cycle common?

-it is common in bacteriophage (viruses that infect bacteria) -in HIV patients.

what happens after the lysogenic cycle?

-it will pop itself back out and into the lytic cycle and produce new viruses. **remember that lytic cyce is the cycle where the new viruses are made.

What are the three types of replication of viruses?

-lytic: all viruses do.. they make new viruses. -lysogenic: dormant phase...dont make new viruses -latent: *remember lysogenic and latent are dormancy phases.

Lytic cycle aka productive cycle

-only cycle that actually produces new viruses. -has 7 steps

how do ppl get infected by chicken pox?

-rare now a days -its a itchy rash that goes away in some days. -transmission: through respiratory root. (makes it very contagious.)

how can you prevent sores from occurring again/reactivating?

-reduce your stress.

explain how chix pox is transmitted.

-someone coughs it out. -another person gets it in their eye, mouth or nose. -the virus travels into the throat.. infects the throat. -the infected person sneezes and infects another person. *when sneezes it out.. the virus is still in the infected person's body..* -goes through the blood stream..liver.. skin and creates rash. **it is contagious during throat.. aka before the rash is present*

what is the difference between generalized and specialized transduction?

-specialized transduction has lysogeny involved!

what happens if the bacteria reproduces through binary fission and it has the virus in lysogenic cycle inside?

-the DNA is integrated in the bacterial chromosome (bc lysogenic cycle) -if the bacteria divides via binary fission, both daughter cells would contain the virus' genetic info. -the genetic info is passed down to next generation and can persist in genome. -it can reactivate and wake back up and kill the bacteria -or doesnt ever reactivate and are like a normal dna.

HHV1 and HHV2 where are each found.

-the HHV2 prefers being in genitals but can be found in the mouth (use your imagination why) -the HHV1 prefers in mouth but can be found in genitals (use your imagination)

what happens when there is a signal that tells the latent cycle to stop and start lytic cycle?

-the LAT transcript is stopped so, virus wakes back up

are these dormant phases always dormant?

-the dormant phases can be forever but they can wake up and integrate into the lytic cycle and produces new viruses. -if never did this, they would never be contagious and would make more viruses **only contagious when in lytic cycle

HHV2 latency

-the latency is similar to the HHVI but the difference is that it goes latent in the sacral plexus nerves which are in the spine not in the trigiminal ganglia (like HHV1) -lives there the rest of your life -like HHV1, in some ppl they never recur but in some, it comes back due to stress/being compromised in the immune system.

what is the coorelation between age and HHV4?

-the older you get this, the worse you are. -just like HHV3 (chicken pox)

what is the difference between the latency and lysogenic replication cycle?

-they are both dormant cycles -latency: -the virus is in your body but it doesnt make you sick nor it gives you symptoms. -the viruses are not replicating. ------------------- Lysogenic: -these are dormant also. -they are a type of latent virus BUT while they are latent, they integrate their genomes in the host's chromosomes.

what if someone who has never had chicken pox touches an infected shingles person and puts the virus in their eyes?

-they get chicken pox not shingles!!! -bc shingles is the next dormant phase of chicken pox -always starts w/ chicken pox.

how does HHV1 and HHV2 manage to be a lifelong thing? osea what is a characteristic of the infection that makes it lifelong?

-they infect neruons.. so, we cant take out neurons. -=they infect something we can't take out so, impossible to avoid.

Burkitt's lymphoma

-type of cancer that is common in Africa -people who are co-infected with HHV4 and Malaria at the same time get this. -has good rate of remission

what is the latency cycle of HHV1 and HHv2 (the neurons around mouth that have to do in HHV1) like?

-when in latency stage, it is actually not a virus. Doesnt have a capsid, no receptors. It is just a genome (just a piece of DNA). -this genome is what stays in the nucleus of the neurons in your face (HSV-1 and HSV-2). -nothing happens... nothing gets expressed/ no mRNA is made/no proteins are made. -it just sits there in latency and waits until it gets a signal that tells it that its good to get out of it.

what is abortive?

-when the virus is unable to complete life cycle

why are bacteriophages important?

-without phages, the whole world would be covered w/ bacteria -they shaped the evolution of bacteria through process called transduction -they help people who are infected w/ bacteria -good to control bacteria when we make wine, cheese (bc we want bacteria but not too much)

what type of signal does it get that makes it get out of latency and into lytic cycle?

1. stress (physical, emotional, immunological [ex: you got infected by something else.. osea got the flu]) --the stress hormones prevents the LAT of doing its job and the lytic cycle starts 2. immunosuppression

describe how HHV1 come about and their life cycle after.

1. the first infection creates a cold sore. -ppl get cold sores through kissing. -the cold sore goes away after some days. -the virus doesnt dissapear. -the virus gets inside the near near the lip. -travels through the nerve into a cluster of nerves near your temple called the Trigeminial ganglia and stays there the rest of your life. -in some people it stays dormant (latent) there.. in others it wakes up and goes back into the lytic cycle and it makes new virus.. new virus goes into nerves, go back into skin and makes sore again that is contagious.

what cycle does bacteriophages go through?

ALL phages undergo lytic cycle SOME phages called Temperate phages undergo lysogeny **only some go through lysogeny**

what is the vaccine against chicken pox?

Oka vaccine.

what is the name of the vaccine given to elderly to avoid them form getting shingles?

ZOSTAVAX

whitlow

a sore in any place outside of your body that is not in the lip (ex: fingers, arms, etc) -common in densist when gloves were not used. -common in MMA fighters.. ex: they hit someone that has cold sore w/ bear hands and their hands have a small cut.. it gets in their cut.

HHV4 latency

affects B cells of immune system -it goes latent in B cells.

what phages go through lytic cycle?

all of them.

HHV6

causes roseola -a rash 3-5 days of high fevers followed by diffuse macular rash, often has febrile seizures

HHV3

chicken pox/ shingles.

Mono symptoms

fever, sore throat, swollen lymph nodes, tires

HHV1

human herpes virus 1 -Transmission - KISSING!!!, contact, skin-skin, saliva, physical contact. -mostly causes cold sores -this virus can cause also sores in inside of the thoat, brain (happens to people who are immunocompromised)

what makes the virus go form lysogenic to lytic? (if it does)

it depends if the bacteria or host cell is good at reproducing... has good resources... -if not good for reproduction, it will stay in lysogenic cycle.. if good= go into lytic.

HHV4

mono or Burkitt's lymphoma -affects B cells of immune system -this is a lifelong virus that goes latent in B cells.

what are the phages that go through lysogeny?

temperate phages.

t cells

they are dormant but, they wake up when you are sick.

What are bacteriophages?

viruses that infect bacteria -they kill bacteria..

is it possible that someone who has been vaccinated for chicken pox can actually get shingles later in life since the vaccine has weak, live chicken pox?

yes! it is possible but very rare.