For which of the following reasons are most animal poxviruses unable to infect humans?
a. Affected animals are not in frequent contact with humans.
b. The human immune system makes it impossible for the foreign viral particles to
reproduce effectively.
c. Attachment to human cells is unlikely.
d. Human cells lack the necessary enzymes for infection.

검증된 단계별 안내

Understand that viral infection begins with the virus attaching to specific receptors on the host cell surface. This attachment is highly specific and determines host range.

Recognize that poxviruses have evolved to bind to receptors present on their usual animal hosts' cells, which may differ from those on human cells.

Consider that if the virus cannot attach effectively to human cell receptors, it cannot enter the cells to initiate infection.

Evaluate the other options: while immune response and enzyme availability are important, the primary barrier for cross-species infection is often the inability to attach to host cells.

Conclude that the most critical reason most animal poxviruses cannot infect humans is due to the unlikelihood of attachment to human cells.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Virus-Host Specificity and Attachment

Viruses infect hosts by attaching to specific receptors on the host cell surface. This attachment is highly specific, meaning that if a virus cannot bind to receptors on human cells, it cannot initiate infection. Poxviruses often have evolved to recognize receptors unique to their animal hosts, limiting cross-species infection.

Host Immune Response to Viral Infection

The human immune system can recognize and neutralize foreign viruses, preventing their replication. However, immune defense usually acts after viral entry, so inability to infect is more often due to initial attachment failure rather than immune clearance. Immune response is crucial but not the primary barrier for many zoonotic viruses.

Viral Replication Requirements in Host Cells

Viruses rely on host cell machinery and enzymes to replicate. If human cells lack specific enzymes or factors required by an animal virus, replication cannot proceed. However, many poxviruses carry their own replication enzymes, making this less commonly the limiting factor for infection in humans.