Lytic and lysogenic cycles are the means of virus reproduction. The relatively more common lytic cycle is the process of viral replication in which the virus invades the host cell. To multiply, it consumes the host’s body and completely destroys the host’s cells.
The lysogenic cycle, not the conventional mode of viral replication, depends largely on the lytic cycle. In this process, the virus combines its genetic information with that of the host and sleeps, continuing its normal activity and allowing the host to reproduce Although sometimes similar, it is important to understand the difference between the genes (lytic cycle) and the lysogenic cycle. .
What is Lytic Cycle?
The lytic cycle begins with a toxic phage infecting a host cell, initiating the production of new phage particles, and finally destroying the cell The T phase can be considered a good example of how the phase of the lytic cycle is maintained.
The first step is attachment when the phage interacts with bacterial surface receptors containing a single protein lipopolysaccharide and OmpC on the host surface.
Most phages have a narrow host range and can infect a single bacterial species or strain. This insight can then be used to treat targeted bacterial infections with phage therapy.
The second stage of the lytic cycle is penetration or penetration. This is done by contracting the tail, which acts as a membrane needle, injecting the viral genome through the cell wall and membrane while the phage head and other remaining components remain outside bacteria.
The third step of infection is the secretion of viral components. This happens after the phage enters the viral compartment and viral endonucleases destroy the bacterial chromosome. It hijacks the host and copies, transcribes and translates all the parts of the virus to assemble a new virus.
The fourth stage is maturation in which new virions are produced followed by the final secreted stage. A fully grown virus bursts out of the host cell in a process called lysis and the nascent virus infects new cells.
What is Lysogenic Cycle?
During the lysogenic cycle, the phage genome enters the host cell through attachment and entry.
A good example of such a life cycle stage is the lambda stage.
During the lysogenic cycle, instead of killing the host, a phage genome called a prophage fuses with the bacterial chromosome and becomes part of the host.
As bacteria reproduce their chromosomes, phage DNA is also copied and passed to new daughter cells during bacterial reproduction The presence of phages can change bacterial phenotype such that phage toxins can induce additional genes (eg toxins that can promote virulence of bacteria) Lysogenic transformation or called. phase transformation. There are some bacteria including Vibrio cholerae and Clostridium botulinum that are less virulent without a prophage.
During the lysogenic cycle, the prophage remains on the host chromosome until induction, allowing the extraction of the viral genome from the host chromosome After insertion, the temperate phage can undergo a lytic cycle and then lysogenize on the newly captured cell.
Difference Between Lytic and Lysogenic Cycle
|Lytic Cycle||Lysogenic Cycle|
|The DNA of the virus doesn’t integrate into the host DNA||The DNA of the virus integrates into the host DNA|
|Host DNA hydrolyzed||Host DNA not hydrolyzed|
|Absence of prophage stage||Presence of prophage stage|
|DNA replication of virus takes place independently from the host DNA replication||DNA replication of the virus takes place along with the host DNA replication|
|Occurs within a short period of time||Takes time|
|Symptoms of viral replication are evident||Symptoms of viral replication not evident|
|Genetic recombination in the host bacterium not allowed||Genetic recombination in the host bacterium allowed|
|The cellular mechanism of the host cell is totally undertaken by the viral genome||The cellular mechanism of the host cell is somewhat disturbed by the viral genome|