02.10 Viral Reproduction

Today we’re going to be talking about Viral reproduction.

In this lesson on viral reproduction we will cover the lytic cycle, the lysogenic cycle and discuss some common human viruses.

 

Viral Reproduction- viruses rely on host cell's machinery to accomplish replication.

Viral life cycle tends to have two paths. The Lytic Cycle-(virulent infection) is the pathway where the virus upon entering host cell uses it's machinery to manufacture viral load in high volumes that cause the cell to lyse, releasing new viral load that in turn infects more cells and repeats the process.

The other path that the virus can switch into is called the Lysogenic Cycle. This is considered a stage of non-virulent infection that uses the host cell as a place of refuge and lies in a dormant state and does not kill the host cell. Integrates its genome into host genome and is passed on when the host cell divides. Transition from lysogenic to lytic- Certain stressors (UV light, chemicals, nutrient levels) can trigger induction= when a virus switches from lysogenic to the lytic phase

 

So this image shows some common human viruses. YOu will noticed multiple shapes and sizes. Common viruses

Herpes virus, rabies virus (the most deadliest of all viruses) ,  Measles, SARS, Ebola, Rotovirus- stomach flu,  Human Papilloma Virus- HPV (associated with cervical cancer), Human Immunodeficiency Virus- HIV, Epstein-Barr Virus- Mononucleosis.

So in review, viruses have two different life cycles, the active, virulent stage called the lytic cycle where the virus is actively making virus particles, assembling them and lysing the host cell to infect more cells. Or if conditions change it can shift into the lysogenic stage where is embeds its nucleic acids into the host genome and thus remains a part of each new cell as it replicates and divides. And finally viruses that infect humans come in various shapes and sizes, some for which we have vaccines and others are yet to be discovered.