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lysogeny

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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lysogeny

Postby lara » Fri Oct 07, 2005 7:43 am

1.is defined as the dormant state of virus,rite?then how cum they cause botulism,diphtheria etc.?
2.y r these diseases still called bacterial??
3.how does bact. benefit out of this process?
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Postby victor » Fri Oct 07, 2005 12:33 pm

Lysogeny is used for determine virus' life cycle. Let me explain it a little (it's my favourite).. :lol:
Viruses know 2 life cycle which are Lytic phase and Lysogenic phase.
In Lytic phase:
virus injects it's genetic material into the host and after that the whole virion is destructed by host's immune system. Inside the host, the genetic material will act in 2 ways (in RNA +sense virus) which are acting like another genetic material for the newly replicated provirus or act like mRNA to translate proteins for the capsid.

You see that when this genetic material synthetizing the protein that they want, the whole cell's protein synthetize is stopped, no regulation.

When this happen, the whole virions is completely replicated and they're already active. the Lysis of the host is because of the "budding" of those virions to the host's membrane. Virions use the host's membrane as the envelope for the whole virions..

In Lysogenic phase:
It's the same as Lytic phase, but the difference is in Lysogenic, the host's regulation is maintained and when it's time for reproduce daugther host, the virus still remain and keep replicating..they only need one "trigger" protein signal to attract them out from the host (By lysis) all together.

from both of them, we can see that in Lytic phase, virus usually more virulent (while not all of them) and do a fast epidemy. While in Lysogenic phase, virus is more dangerous because they keep replicate and when it's time for 'trigger', you know how many viruses will attack suddenly to your system... :lol:

2.for the botulism and diphteria, they're called bacterial disseases because they're cause by bacteria.
Botulism = Clostridium botulinum
Diphteria = I forgot

3. bacterias take benefits by retaking the protein synthesis from the host for their own purpose.

Sorry if all these thing are too complicated... :lol:
Hope this pot helps you.
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Postby canalon » Fri Oct 07, 2005 1:21 pm

Well a few more details:

1- Victor answer is correct except for the entry part: The virus first enter the host then inject it's genetic material inside one of the host's cell were it can start its life either as lysogenic or lytic virus.

About causing diseases, I did not check if its true for botulism and diphteria, but I take your word for it, its easy. The virus genetic material is not only carrying instruction for replicating itself, it also takes as hitchhikers some bacterial genes that codes for toxin production. Once in the lysogenic stage those toxin are expressed in the bacteria and cause the ilnesses symptoms.

2- Should be clear reading the paragraph above: The toxins are carried by virus targeting bacteria (bacteriophages) and expressed only by the bacteria carrying the lysogenic form of the phage. When those bacteria infect a suitable/sensitive host (a human being for example) they will cause the disease.
By the way diphteria is caused by Corynebacterium diphteriae

3- Aside from the benefits of parasitic lifestyle of pathogenic bacteria (Victor's answer, but considering the first question, he was answering to the wrong question 8) ) How do bacteria benefits from lysogenic phages? Now you should have figured out by yourself that they are benefiting from those extra genes that gives them a better chance of survival into a host by increasing their virulence.

HTH

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Postby victor » Sun Oct 09, 2005 12:31 pm

Um, I've heard about it also...but still cloudy in my mind...it's about endotoxin and exotoxin which is programmed by viruses...

Oh, more addition, in Lysogeny phase, virus also combine their gene with the host's gene...and when it's time for the host to do mitosis or binnary fission, the host will replicate the copy of the combined DNA..so, virus's gene also get replicated..smart eh?? :lol:

For the entry part, yup, I guess I explained it too raw..well, this is the detailed one about the entry..
the first thing is for the host (receptor) and the virus (anti-receptor or virus attachment binding-VAB). Virus can attach to certain part of the host specific receptors and make it attached. After that, virus leak a little bit of the host's membrane by secreting a little esterase and then, it injects it's genetic material to the host's cytoplasm. After injecting it's genetic material, the whole virion (now without it's genetic material) will be destructed by host's immune system or host's activity.
Because of this period (destruction of the 'empty' virions), there're some amounts of time where the activity of the virus seems gone..this is called by Eclipse period.

By the way Sir Patrick...is this correct??
HTH = Hope This Helps
:D
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Postby canalon » Sun Oct 09, 2005 10:35 pm

victor wrote:For the entry part, yup, I guess I explained it too raw..well, this is the detailed one about the entry..
the first thing is for the host (receptor) and the virus (anti-receptor or virus attachment binding-VAB). Virus can attach to certain part of the host specific receptors and make it attached. After that, virus leak a little bit of the host's membrane by secreting a little esterase and then, it injects it's genetic material to the host's cytoplasm. After injecting it's genetic material, the whole virion (now without it's genetic material) will be destructed by host's immune system or host's activity.
Because of this period (destruction of the 'empty' virions), there're some amounts of time where the activity of the virus seems gone..this is called by Eclipse period.

By the way Sir Patrick...is this correct??


Well except that for bacteriophage the part after the injection do not make sense since there is no one to destroy empty virion, and no eclipse either.
It would have been correct though if we had been talking about viral infection of a whole organism :wink:

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Postby victor » Mon Oct 10, 2005 11:43 am

:D Ow...I don't get so clear about phage since I only study for animal viruses and lesions...
Viral infection is classified as the unique, smart and the modern one..it's so challenging and attracting lerning those.. :lol:
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Postby victor » Thu Oct 13, 2005 11:17 am

Canalon wrote:Well except that for bacteriophage the part after the injection do not make sense since there is no one to destroy empty virion, and no eclipse either.
It would have been correct though if we had been talking about viral infection of a whole organism :wink:

Patrick


Hey, sir Patrick, I found these writing in my virology book.
"Virus is the only infectious agent that got destructed after inject it's genetic material" The word 'virus' here is the general one right? or is there any exception?
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lysogeny

Postby lara » Thu Oct 13, 2005 11:23 am

the time period b/w the injection of the viral dna in2 the host till the appearance of a viable progeny-is this not the eclipse period?y the fuss about destroyin' the empty coat??
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Postby victor » Thu Oct 13, 2005 12:31 pm

Eclipse period is the period where there seems no viral activity [even the sign that the virus is replicating itself were gone]. Maybe eclipse period occurs when the virus' genetic material try to reach the host's nucleus. But some complex viruses I think don't have this period, like Poxviridae and Herpesviridae which already equiped with some polymerase enzymes carried by them...
For the second question, it's still a mistery...
Oh, next time please don't use any uncommon short words...I nearly can't read them.. :oops:
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lysogeny

Postby lara » Sat Oct 15, 2005 10:52 am

sorry :) a habit i am trying to get over.
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Postby victor » Mon Oct 17, 2005 12:08 pm

It's okay, we're here all to study and discussing bio, not like a teacher and a student.. :D
Oh, a little bit addition, for the eclipse period, some viruses also have their eclipse period until they synthesize their genetic material...so, your post before is right.... :D ..sorry for the mistake.. :oops:
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