Viral Replication Process

Viral Replication

• Viruses are made of only proteins and one type of nucleic acid, and have no organelles to make copies of themselves, so they need to get inside other cells to use their ATP and organelles to replicate.
• There are three ways for viruses to get inside a cell:
  • Bacterial phages inject their genetic material directly into the cell
  • Non-enveloped viruses trick the cell's receptors into letting them in
  • Enveloped viruses can either trick the cell's receptors or directly fuse with the membrane

Lytic Cycle

• The impatient virus takes over the cell's machinery, using ATP, ribosomes, nucleic acids, and amino acids to make copies of its genetic material and proteins.
• The viral proteins self-assemble to form fully functional viruses.
• The cell eventually breaks open (lyses), releasing the new viruses into the environment, where they can infect other nearby cells.
• This method is ideal when there are many hosts available and the goal is to create a large army quickly.

Lysogenic Cycle

• The virus decides to "hitch a ride" and sneak into the cell, combining its genetic material with the host's genetic information to remain dormant.
• The virus is repressed, not expressed or transcribed, and is called a provirus or prophage.
• This is referred to as a dormant or latent phase, where the host cell continues to replicate and the virus is replicated along with it.
• In rare cases, the virus can become active if the host cell is weakened or exposed to certain stimuli, leading to the virus making copies of itself and eventually lysing the cell.

Key Terms

• Lytic cycle: the method where the virus takes over the cell's machinery to replicate itself quickly.
• Lysogenic cycle: the method where the virus remains dormant and replicates along with the host cell.
• Proviruses or prophages: the dormant or latent form of the virus.
• Repressor genes: genes on the virus that keep it dormant and inactive.

Learn about the steps involved in viral replication, including how viruses enter host cells and use their ATP and organelles to make copies of themselves. Review the three ways of viral entry and get familiar with the process of viral replication.