What is the Difference Between Virulent and Temperate Phage?

The main difference between virulent and temperate phages lies in their mode of replication and interaction with their host bacteria. Here are the key differences between the two:

Virulent Phages:

• Replicate solely via the lytic cycle, which involves the production of many progeny as soon as the phage's DNA is injected into the host cell.
• Kill bacteria during the lytic cycle.
• Cannot integrate their viral genome into the bacterial chromosome.
• Show generalised transduction.

Temperate Phages:

• Replicate via both lytic and lysogenic cycles.
• Can integrate their viral genome into the bacterial chromosome, which is referred to as a prophage.
• Do not immediately kill the host bacterium after the infection.
• Show specialised transduction.

During the lysogenic cycle, temperate phages do not kill the host cell; instead, they integrate into their chromosomes and become part of the host cell. When the bacterial host cell contains a prophage, it is called a Lysogen. In contrast, virulent phages reproduce via the lytic cycle, which results in the lysis of the host cell.

Comparative Table: Virulent vs Temperate Phage

Virulent and temperate phages are two types of bacteriophages that differ in their life cycles and interactions with their host bacteria. Here is a table summarizing the differences between them:

• Lytic Cycle: Virulent phages have a lytic cycle, where they hijack the host cell machinery to produce new phage particles and eventually lyse the host cell. Temperate phages, on the other hand, do not have a lytic cycle.

• Lysogenic Cycle: Virulent phages do not have a lysogenic cycle, while temperate phages do. In the lysogenic cycle, the phage integrates its genome into the host bacterial chromosomes as a prophage.

• Host Lysis: Virulent phages cause host lysis, releasing their viral progeny, whereas temperate phages do not cause host lysis.

• Integrase Enzyme: Virulent phages do not have an integrase enzyme, which is responsible for integrating the phage genome into the host genome. Temperate phages have an integrase enzyme.

• Prophage Integration: Virulent phages do not integrate their genomes into the host genome, while temperate phages do.

• Mutually Beneficial Relationship: Virulent phages do not have a mutually beneficial relationship with their host, as they eventually lyse the host cell. Temperate phages, however, have a mutually beneficial relationship with their host, as they do not cause host lysis and can provide advantages to the host, such as increased resistance to other phages or improved survival in certain environments.

• Adaptive Attenuates: Virulent phages do not have adaptive attenuates, which are mechanisms that allow temperate phages to switch between lytic and lysogenic cycles in response to environmental changes.