Recombination of Viral Genomes | HHMI BioInteractive Video

Summary

In this video, the process of genetic recombination in influenza viruses is explained. Two different strains of influenza infect the same host cell, where their RNA genomes mix, leading to the creation of new recombinant virus particles. These particles contain genetic material from both parent strains and are assembled and released from the host cell. The recombination occurs through the swapping of whole viral genomes, not by traditional crossing over. The new recombinant strains that are most suited to survival will propagate, contributing to the emergence of new variants in nature.

Takeaways

• 😀 Influenza virus strains can recombine at the single-cell level, generating new human hemagglutinin types.
• 😀 Two influenza strains, represented by red and blue genomic segments, are used to demonstrate viral recombination.
• 😀 Recombination occurs when two different influenza strains infect the same host cell simultaneously.
• 😀 Viral particles bind to the cell surface receptors, fuse with the plasma membrane, and release their genetic material into the cell.
• 😀 After entering the cytoplasm, the viral genomes disassemble and begin replicating.
• 😀 The replication process involves RNA-dependent RNA replication, leading to the generation of numerous viral RNA copies.
• 😀 Because two different viral strains infect the same cell, their RNA segments can mix, facilitating genetic recombination.
• 😀 As viral genomes are packaged into new virus particles, some may include a combination of genetic material from both strains.
• 😀 This genetic exchange, called recombination, results from the mixing of viral subunits, not from crossover events.
• 😀 New recombinant virus particles are created with a mixture of subunits from both strains, leading to a diverse set of viral variants.
• 😀 Recombinant viruses are released from the cell and circulate, with those that perform best in nature surviving and propagating.

Q & A

What is the main process illustrated in the video?

The video illustrates the genetic recombination process between two influenza virus strains when they infect the same human cell.

How are the influenza strains identified in the video?

The influenza strains are identified by their genomic segments, one labeled with red and the other with blue.

What happens when two different strains of the influenza virus infect the same cell?

When two different strains infect the same cell, their RNA subunits mix, leading to the creation of recombinant viruses with mixed genetic material from both strains.

How do the influenza viruses enter the human cell?

The influenza viruses bind to the surface receptors of the cell, fuse with the plasma membrane, and release their genomic material into the cytoplasm.

What happens after the influenza virus releases its RNA into the cytoplasm?

Once the viral RNA is released, it is transcribed and translated to generate viral proteins, and RNA-dependent RNA replication occurs to produce more copies of the viral genome.

What is the significance of RNA subunit mixing in this process?

The mixing of RNA subunits from different viral strains is crucial for recombination, as it leads to the formation of new viral variants with mixed genetic components.

What are recombinant viruses, and how do they form?

Recombinant viruses are new viral strains formed when RNA subunits from two different influenza strains mix during replication and are packaged together in a single virus particle.

How are the recombinant influenza viruses assembled?

The recombinant viruses are assembled by combining the newly replicated RNA subunits with viral proteins to form progeny virus particles.

What happens to the recombinant viruses after they are assembled?

After assembly, the recombinant viruses acquire their viral envelopes and are released from the cell, where they can go on to infect new cells.

Why do new recombinant influenza strains emerge in nature?

New recombinant influenza strains emerge due to genetic mixing during co-infection, and those variants that are more successful in nature (e.g., better adapted to survival) will thrive.