Mechanisms in virus latency

Mechanisms in virus latency

THIS WILL NOT BE ON THE FINAL EXAM!

THIS WILL NOT BE ON THE FINAL EXAM!

Why is every viral infection not productive?

Why is every viral infection not productive?

Bacteriophages - - When infects a bacterial cell, there are two possible outcomes a lytic infection in which new viruses are made, or lysogeny in which the bacteriophage integrates its DNA

genome into the host cell DNA and new viruses are not made. What benefit does lysogeny provide for the virus?

To exchange a chancy existence for one in which reproduction of progeny is assured.

As long as the bacteria keep reproducing, the virus, in the form of the viral genome, will also be reproduced.

Does lysogeny provide any benefit to the host? It may carry a selective value for the host and confer new

characteristics to the host.

Bacteriophages - - When infects a bacterial cell, there are two possible outcomes a lytic infection in which new viruses are made, or lysogeny in which the bacteriophage integrates its DNA

genome into the host cell DNA and new viruses are not made. What benefit does lysogeny provide for the virus?

To exchange a chancy existence for one in which reproduction of progeny is assured.

As long as the bacteria keep reproducing, the virus, in the form of the viral genome, will also be reproduced.

Does lysogeny provide any benefit to the host? It may carry a selective value for the host and confer new

characteristics to the host.

Do animal viruses undergo lysogeny?

Do animal viruses undergo lysogeny?

Animal viruses Animal viruses don’t undergo “lysogeny”, but some

do cause latent infections. Latent infections in animal viruses are similar to

lysogeny in bacteriophages in that: During a latent infection, the virus is quiescent with no

progeny being produced. The virus co-exists with the host and survives as long as

the host survives Latent infections in animal viruses differ from

lysogeny in bacteriophages in several ways: With the exception of HIV, which is a retrovirus, the virus

does not integrate its DNA, into the host cell DNA, but remains as a episome.

Animal viruses Animal viruses don’t undergo “lysogeny”, but some

do cause latent infections. Latent infections in animal viruses are similar to

lysogeny in bacteriophages in that: During a latent infection, the virus is quiescent with no

progeny being produced. The virus co-exists with the host and survives as long as

the host survives Latent infections in animal viruses differ from

lysogeny in bacteriophages in several ways: With the exception of HIV, which is a retrovirus, the virus

does not integrate its DNA, into the host cell DNA, but remains as a episome.

Latent infectionsLatent infections The latent infection begins with a productive infection

and then the virus becomes latent. The productive infection may occur in one cell type while

the latent infection is found in a different cell type. Latent infections can reactivate to cause a

productive infection, and the new virus particles can infect a new susceptible host. The original host still retains a latent infection. Reactivation may be due to a breakdown of the immune

system or the patient may be experiencing some sort of stress.

The reactivation disease may be different from the original productive infection (chicken pox versus shingles in varicella-zoster infections).

The latent infection begins with a productive infection and then the virus becomes latent.

The productive infection may occur in one cell type while the latent infection is found in a different cell type.

Latent infections can reactivate to cause a productive infection, and the new virus particles can infect a new susceptible host. The original host still retains a latent infection. Reactivation may be due to a breakdown of the immune

system or the patient may be experiencing some sort of stress.

The reactivation disease may be different from the original productive infection (chicken pox versus shingles in varicella-zoster infections).

What animal viruses cause latent infections?

What animal viruses cause latent infections?

All Herpesvirus infections HSV I and II EBV VZV CMV Human herpes viruses 6, 7, and 8

HIV

All Herpesvirus infections HSV I and II EBV VZV CMV Human herpes viruses 6, 7, and 8

HIV

HSV-I HSV-I

The initial productive infection takes place in epithelial cells of the oral cavity.

HSV is neurotropic and it establishes a latent infection by entering a sensoty nerveaxon ner the infection site.

The virus then moves to the neuron’s nucleus in the trigeminal nerve ganglion

The initial productive infection takes place in epithelial cells of the oral cavity.

HSV is neurotropic and it establishes a latent infection by entering a sensoty nerveaxon ner the infection site.

The virus then moves to the neuron’s nucleus in the trigeminal nerve ganglion

HSV-I acute versus latent infection

HSV-I acute versus latent infection

HSV I and IIHSV I and II