Quick Question about viruses!

[040111333]

Do all viruses undergo replication through either the lytic or lysogenic cycle? Or is this specific to bacteriophages? I'm confused by this because HIV virus also enters the lysogenic cycle, but this is not a bacteriophage…however, TPR says that the lytic and lysogenic cycles are specifically bacteriophage life cycles I'm confused.

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[iRonDevil91]

It is true that viruses can be lytic or lysogenic depending on how they evolved. This is most commonly dictated by how their genome is encoded. RNA based viruses can propogate themselves lytically or lysogenically, while DNA viruses tend to be more commonly lysogenic. There are exceptions to both rules. I like to think of it this way: if a virus is RNA-based, then it can proceed lytically because the cell will replicate its genome in the cytosol and never needs to become incorporated. DNA viruses however, have to enter the nucleus for transcription, and commonly, integrate in the process.

HIV is an RNA virus, but it is one of the exceptions to the above rule since it is a retrovirus, which is special in nature in that it is encoded by an RNA genome, but undergoes reverse transcription to generate a DNA that can become incorporated into the host genome. I think knowing this is sufficient for the MCAT

 

[Brill4]

Nice detail, but you didn't answer OP's question.
OP, for animal viruses, they first need to bind to the surface receptor on the plasma membrane and from there many animal viruses enter the cell through endocytosis. After the genome is uncoated within the cell (or viruses can sometimes fuse to the plasma membrane) it can then go through 3 paths: lytic, lysogenic or productive cycle. The productive cycle is similar to lytic except that it doesn't destroy the host cell.

So animal viruses need a few extra steps before the lytic and lysogenic cycle, and they also have an additional one called the productive cycle. Also it might be important to know that in the animal virus lysogenic cyce, the dormant form of the viral genome is called a provirus rather than prophage in bacteriophages.