Which pox virus won’t grow in egg, animal cells –
**Core Concept**
The question tests the understanding of the growth characteristics of different pox viruses, specifically their ability to replicate in various cell cultures such as egg and animal cells. Pox viruses are a family of large, complex viruses that include the viruses causing smallpox, cowpox, and molluscum contagiosum. The ability of a virus to grow in a particular cell type depends on the presence of specific receptors and the viral replication machinery.
**Why the Correct Answer is Right**
Molluscum contagiosum virus is known for its strict tropism for human epithelial cells and its inability to replicate in common laboratory cell lines, including those derived from eggs (e.g., chick embryo cells) and most animal cells. This characteristic makes it unique among pox viruses and poses a challenge for its cultivation and study.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because other pox viruses can grow in egg or animal cells.
**Option B:** Incorrect as some pox viruses can be adapted to grow in certain cell lines.
**Option D:** Incorrect because it does not specify the correct virus.
**Clinical Pearl / High-Yield Fact**
Molluscum contagiosum is a skin infection caused by a poxvirus, characterized by small, pearly, or flesh-colored lesions. The virus's inability to grow in standard cell cultures highlights the need for specific diagnostic approaches, such as clinical diagnosis or PCR.
**Correct Answer:** D. Molluscum contagiosum.