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Jan 28
The replication cycle of HIV virus can be divided into six stages:
1. Attachment: The first stage of the replication cycle is attachment. The HIV virus attaches itself to the surface of a host cell by binding to specific receptors on the cell membrane. The primary receptor used by HIV is the CD4 receptor, which is found on the surface of immune cells called T-helper cells.
2. Fusion: After attachment, the HIV virus fuses with the host cell membrane, allowing the viral genetic material to enter the cell. This fusion is facilitated by the viral protein gp41, which undergoes a conformational change to bring the viral and cellular membranes close together.
3. Reverse Transcription: Once inside the host cell, the HIV virus uses its own enzyme called reverse transcriptase to convert its single-stranded RNA genome into double-stranded DNA. This process is known as reverse transcription and is a unique characteristic of retroviruses like HIV.
4. Integration: The newly synthesized viral DNA is then transported into the nucleus of the host cell, where it is integrated into the host cell's DNA. This integration is mediated by the viral enzyme integrase, which inserts the viral DNA into a specific site within the host cell's genome.
5. Transcription and Translation: Once integrated, the viral DNA is transcribed by the host cell's machinery into messenger RNA (mRNA). This mRNA is then translated by the host cell's ribosomes to produce viral proteins, including the structural proteins (capsid, matrix, and envelope proteins) and the enzymes (protease, reverse transcriptase, and integrase) necessary for viral replication.
6. Assembly and Release: The final stage of the replication cycle involves the assembly and release of new viral particles. The viral proteins and RNA are assembled into immature viral particles, which then bud from the host cell membrane, acquiring an envelope derived from the host cell. The newly formed viruses are then released into the extracellular space, ready to infect other host cells and continue the replication cycle.
1. Attachment: The first stage of the replication cycle is attachment. The HIV virus attaches itself to the surface of a host cell by binding to specific receptors on the cell membrane. The primary receptor used by HIV is the CD4 receptor, which is found on the surface of immune cells called T-helper cells.
2. Fusion: After attachment, the HIV virus fuses with the host cell membrane, allowing the viral genetic material to enter the cell. This fusion is facilitated by the viral protein gp41, which undergoes a conformational change to bring the viral and cellular membranes close together.
3. Reverse Transcription: Once inside the host cell, the HIV virus uses its own enzyme called reverse transcriptase to convert its single-stranded RNA genome into double-stranded DNA. This process is known as reverse transcription and is a unique characteristic of retroviruses like HIV.
4. Integration: The newly synthesized viral DNA is then transported into the nucleus of the host cell, where it is integrated into the host cell's DNA. This integration is mediated by the viral enzyme integrase, which inserts the viral DNA into a specific site within the host cell's genome.
5. Transcription and Translation: Once integrated, the viral DNA is transcribed by the host cell's machinery into messenger RNA (mRNA). This mRNA is then translated by the host cell's ribosomes to produce viral proteins, including the structural proteins (capsid, matrix, and envelope proteins) and the enzymes (protease, reverse transcriptase, and integrase) necessary for viral replication.
6. Assembly and Release: The final stage of the replication cycle involves the assembly and release of new viral particles. The viral proteins and RNA are assembled into immature viral particles, which then bud from the host cell membrane, acquiring an envelope derived from the host cell. The newly formed viruses are then released into the extracellular space, ready to infect other host cells and continue the replication cycle.
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