Virus lacking hemagglutinin and neuraminidase but having membrane fusion protein is ?
**Core Concept**
The question is testing the student's knowledge of viral structure and replication, specifically the characteristics of different viral families and their surface proteins. Hemagglutinin and neuraminidase are surface glycoproteins found on influenza viruses, which facilitate infection by binding to and releasing from host cells. Membrane fusion proteins, on the other hand, are responsible for fusing the viral envelope with the host cell membrane, allowing the virus to release its genetic material into the host cell.
**Why the Correct Answer is Right**
The correct virus lacking hemagglutinin and neuraminidase but having a membrane fusion protein is the HIV (Human Immunodeficiency Virus) virus. HIV is a member of the Retroviridae family, which uses a membrane fusion protein called gp41 to fuse with the host cell membrane. This fusion is mediated by the binding of gp41 to the host cell's CD4 receptor and a co-receptor, allowing the virus to release its reverse transcriptase enzyme and integrate its genetic material into the host cell's DNA.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a virus that lacks hemagglutinin and neuraminidase but has a membrane fusion protein. While some viruses may have similar characteristics, this option is too vague to be correct.
**Option B:** This option is incorrect because it does not accurately describe a virus that lacks hemagglutinin and neuraminidase but has a membrane fusion protein. Influenza viruses, for example, have hemagglutinin and neuraminidase but do not have a membrane fusion protein.
**Option C:** This option is incorrect because it does not specify a virus that lacks hemagglutinin and neuraminidase but has a membrane fusion protein. While some viruses may have similar characteristics, this option is too vague to be correct.
**Option D:** This option is incorrect because it does not accurately describe a virus that lacks hemagglutinin and neuraminidase but has a membrane fusion protein. Some viruses may have similar characteristics, but this option is not specific enough to be correct.
**Clinical Pearl / High-Yield Fact**
It's worth noting that the Retroviridae family, which includes HIV, is a large and diverse group of viruses that can cause a range of diseases, including AIDS. Understanding the characteristics of these viruses is crucial for developing effective treatments and prevention strategies.
**Correct Answer: C. HIV**