Question

Can viroids infect humans?

Answer 1

Hint: Viroids are the smallest infectious agents that may sometimes be similar to the viruses and infects mainly higher plants. Viroids can be transmitted by aphids, mechanical damage to parts of the plant, and by leaf-to-leaf contact.

Complete answer:
Viroids are the smallest pathogens known to humans that infect only the higher plant and cause several diseases in them. They are not found to be infectious in humans or animals. The genetic material found in them is single-stranded without the protein coat. Thus, the coding for protein is absent but they are capable of replication when transferred to the host cell.
Viroids are small in size and have single-stranded circular RNA present in them. They have a small sequence of RNA which have less than a thousand base pairs. They have RNA which does not code for any protein substances. They depend on the plant viruses for their replication and encapsidation. Theodor Otto Diener, a plant pathologist who was the one to discover the viroids. In the year 1971, the name and their discovery were made by T.O.Diener. Potato spindle tuber viroid (PSTVD) was the first viroid that was discovered. They tend to replicate with the help of an enzyme called RNA polymerase II. The viroids differ from viruses in structure as they lack protein coat. The mature viroids only infect the plants but do not infect humans and thus do not cause any disease in them. It leads to an economic loss of the plant they cause disease in. The viroid’s when infecting a plant they utilize proteins of the host plant for their basic biological functions like replication, processing, transport, and pathogenesis.

Note:
D.J. Iwanowski is known as the father of virology and is credited with discovering the Tobacco Mosaic Virus. The virus that causes Hepatitis D in the case of humans is found to be almost similar to a viroid. The viroids have mainly two families named, Pospiviroidae and Avsunviroidae.