Which virus cannot be cultivated?

Ans. is 'c' i.e., Molluscum contagiosum (Ref: Ananthanarayan, 9th/e, p. 465 and 8th/e, p. 465)* Humans are the only susceptible host. This disease is caused by molluscum contagiosum belongs to poxvirus. It is an enveloped, dsDNA - containing virus with complex symmetry. This is a noncultivable virus.* The infection is sexually transmitted and manifests as umbilicated fleshy lesions. The infection is diagnosed by demonstrating intracytoplasmic inclusions called as molluscum bodies or Henderson - Peterson bodies.* Cell cultures can be used for virus isolation, though culture of variola virus is only attempted in Biosafety Level 4 facilities. The ortho poxviruses grow well in cultured cells; para poxviruses and tana poxvirus grow less well, and molluscum contagiosum virus cannot be cultured.