This content delves into the complex structures of viruses, highlighting the role of capsids in disease causation and the diversity of viral genomes. It examines the structural features of HIV and influenza, their replication strategies, and the importance of structural proteins throughout the viral life cycle. Additionally, it discusses virus classification based on structural characteristics, which is crucial for understanding their pathogenicity and interaction with host cells.
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The viral capsid is made up of protein units called capsomeres and can have various shapes, playing a crucial role in the virus's ability to infect and evade the host's immune defenses
Protection and Packaging of Genetic Material
The capsid serves as a protective shell for the viral genome and is involved in efficiently packaging the genetic material
Interaction with Host Cells
The capsid proteins can interact with host cell receptors to facilitate viral entry and can determine the virus's ability to escape immune surveillance
The helical capsid of the Tobacco Mosaic Virus is crucial for its infectivity in plants, while the conical capsid and reverse transcriptase of HIV are essential for its replication and integration into the host's genome
Viral genomes can come in various forms and are highly efficient in maximizing functionality with minimal genetic content
Retroviruses, like HIV, use reverse transcriptase to synthesize DNA from their RNA template and integrate it into the host's genome for replication
The segmented RNA genome of the influenza virus allows for rapid antigenic shifts and drifts, contributing to its epidemic and pandemic potential
The viral envelope, derived from the host cell membrane, is studded with glycoproteins that mediate attachment and fusion with target cells, playing a crucial role in the virus's life cycle
The spike protein of SARS-CoV-2 is a structural protein that facilitates the virus's entry into human cells and has been a primary target in vaccine development
Enveloped viruses have a lipid bilayer that aids in entry into host cells and can help the virus evade immune detection
Non-enveloped viruses rely on a rigid capsid for protection and often exit the host cell by causing cell lysis
Complex viruses, like bacteriophages, have elaborate structures with additional components, such as tail fibers, for injecting their DNA into host bacteria
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Virus composition excluding capsid
Genetic material (DNA or RNA) and, in some cases, an outer lipid envelope from host cell membrane.
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Capsomere function in virus structure
Protein units that assemble into the capsid, determining its shape: icosahedral, helical, or complex.
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Virus interaction with host cells
Viruses attach to host cells, penetrate them, initiate infection, and evade immune defenses.
