HIV life cycle: How HIV infects a cell and replicates itself using reverse transcriptase

Summary

The video explains the lifecycle of HIV, detailing how the virus infects T helper cells. It describes the process of viral entry, where HIV uses CD4 and CCR5 receptors to fuse with the host cell membrane, allowing its RNA and enzymes to enter the cell. Reverse transcriptase converts the viral RNA into DNA, which integrates into the host genome via integrase, establishing a lifelong infection. The viral components are then produced, transported, and assembled at the cell surface. Finally, protease processes the polyprotein chains, resulting in mature virions that can infect other cells, perpetuating the cycle of infection.

Takeaways

• 🦠 HIV is a retrovirus characterized by an outer envelope and two RNA copies, along with reverse transcriptase, an enzyme that converts RNA to DNA.
• 🔬 The virus infects T helper cells by binding to the CD4 receptor and using the co-receptor CCR5 to facilitate entry.
• ⚙️ Upon binding, the viral envelope fuses with the host cell membrane, injecting the viral genetic material into the cell.
• 🧬 Once inside, the viral RNA is reverse transcribed into single-stranded DNA and then into double-stranded DNA by reverse transcriptase.
• 📥 The integrase enzyme allows the viral DNA to integrate into the host's chromosome, establishing lifelong infection.
• 📄 Messenger RNA is produced from the integrated viral DNA, encoding various viral proteins needed for replication.
• 🏭 Viral proteins are synthesized in the rough endoplasmic reticulum and transported to the cell surface to form new virions.
• 🌐 The RNA, enzymes, and proteins coalesce at the cell surface to begin the budding process, forming new viral particles.
• 🔄 A key enzyme, protease, cleaves the polyprotein chains to produce mature viral components necessary for infectivity.
• 🚀 Mature virions are released from the host cell, allowing the infection cycle to continue as they seek to infect new cells.

Q & A

What type of virus is HIV?

HIV is a typical retrovirus, characterized by an outer envelope and two copies of RNA in its center.

What is the role of reverse transcriptase in the HIV lifecycle?

Reverse transcriptase converts the viral RNA into DNA, a crucial step for HIV to replicate within host cells.

How does HIV infect T helper cells?

HIV infects T helper cells by binding to the CD4 receptor and a co-receptor called CCR5, leading to the fusion of the viral and host cell membranes.

What happens to the HIV envelope protein during infection?

The HIV envelope protein remains at the surface of the host cell after injecting the viral genetic material into the cell.

What is the significance of integrase in the HIV lifecycle?

Integrase allows the double-stranded viral DNA to integrate into the host chromosome, establishing a lifelong infection.

What process does RNA polymerase facilitate in HIV-infected cells?

RNA polymerase synthesizes messenger RNA (mRNA) from the integrated viral DNA, which encodes various viral proteins.

How are envelope proteins processed in the infected cell?

Envelope proteins are produced in the rough endoplasmic reticulum and embedded into the cell membrane before clustering on the surface.

What role does protease play in the maturation of HIV?

Protease breaks down polyprotein chains into their component parts, allowing the formation of mature viral structures.

What is a mature virion, and why is it important?

A mature virion is an infectious particle that can go on to infect other cells, perpetuating the HIV lifecycle.

What ultimately happens to the infected host cell after HIV replication?

The infected host cell produces a large number of viruses, which continues the infection process.