Animal Viruses: 1. Attachment to the Host Cell: Videos & Practice Problems

Animal viruses initiate infection by attaching to host cells, a process similar to bacteriophage attachment. This crucial step involves spike proteins on the virus that bind to specific host cell receptors, facilitating entry into the cell. Non-enveloped viruses have spike proteins on their surface, while enveloped viruses feature these proteins protruding from a lipid envelope. Understanding this attachment mechanism is essential for grasping the subsequent stages of viral infection and pathogenesis.

Animal Viruses: 1. Attachment to the Host Cell

Animal viruses initiate infection through a critical first step known as attachment to the host cell. This process is remarkably similar to that of bacteriophages, relying heavily on protein interactions. Specifically, animal viruses utilize spike proteins located on their surface to recognize and bind to specific receptors on the host cell. This binding is essential as it facilitates the virus's entry into the host cell, marking the transition to the next phase of infection.

To illustrate this process, consider two types of viruses: non-enveloped and enveloped. Non-enveloped viruses have spike proteins directly on their protein coat, which interact with receptor proteins on the host cell's surface. This interaction signifies the attachment stage. In contrast, enveloped viruses possess an outer lipid layer that encases their protein coat. The spike proteins protrude through this lipid envelope, allowing them to engage with host cell receptors similarly. This interaction is crucial for the attachment necessary for subsequent entry into the host cell.

Understanding the attachment mechanism is vital for comprehending how animal viruses establish infections. The spike proteins' role in binding to host cell receptors is a fundamental aspect of viral pathogenesis, setting the stage for further exploration of animal virus infections in future studies.

The first step of a viral infection is virus ______________, when the spike proteins of the virus attach to the ___________ of the host cell.

• A. Entry; plasma membrane.
• B. Attachment; surface receptors.
• C. Uncoating; DNA.
• D. Assembly; receptor proteins.

Answer: (B)

An antiviral drug specifically modifies viral receptors on a eukaryotic host cell. How might this affect the viral reproductive cycle?

• A. It would stop the virus from attaching to the host cell.
• B. It would facilitate the process of entry via endocytosis.
• C. It would result in the uncoating of the viral DNA.
• D. It would increase the production of viral proteins by the host cell.

Answer: (A)

Here’s what students ask on this topic:

What is the first step in an animal virus infection?

The first step in an animal virus infection is the attachment to the host cell. This process involves spike proteins on the surface of the virus recognizing and binding to specific receptors on the host cell. This binding is crucial as it allows the virus to attach firmly to the host cell, facilitating its entry into the cell, which is the subsequent step in the infection process. Understanding this initial attachment is essential for comprehending how viruses invade host cells and initiate infection.

How do spike proteins function in the attachment of animal viruses to host cells?

Spike proteins on the surface of animal viruses play a critical role in the attachment to host cells. These proteins specifically recognize and bind to receptor proteins on the host cell's surface. This interaction is highly specific, ensuring that the virus attaches to the correct host cell type. The binding of spike proteins to host cell receptors is the first step in the viral infection process, enabling the virus to enter the host cell and begin replication.

What is the difference between enveloped and non-enveloped viruses in terms of attachment?

Enveloped and non-enveloped viruses differ in their structure and attachment mechanisms. Non-enveloped viruses have spike proteins directly on their protein coat, which interact with host cell receptors. In contrast, enveloped viruses have an outer lipid envelope surrounding their protein coat, with spike proteins protruding through this lipid layer. Despite these structural differences, both types of viruses use their spike proteins to bind to specific receptors on the host cell, facilitating attachment and subsequent entry.

Why is the attachment step crucial for viral infection?

The attachment step is crucial for viral infection because it determines the virus's ability to enter the host cell. Without successful attachment, the virus cannot penetrate the host cell membrane and initiate the infection process. The specific interaction between viral spike proteins and host cell receptors ensures that the virus attaches to the correct cell type, which is essential for the virus to replicate and propagate within the host organism. This step is a key target for antiviral strategies aiming to block infection.

How do host cell receptors influence the specificity of viral attachment?

Host cell receptors play a significant role in the specificity of viral attachment. These receptors are specific proteins or molecules on the surface of host cells that the viral spike proteins recognize and bind to. The compatibility between the viral spike proteins and the host cell receptors determines which cells a virus can infect. This specificity ensures that viruses attach only to suitable host cells, facilitating efficient entry and infection. Understanding these interactions is crucial for developing targeted antiviral therapies.