Question

Gemini viruses are:

• A. Circulative type
• B. Non-circulative type
• C. Persistent type
• D. Non-persistent type

Hint:

Geminiviruses (Begomoviruses) are circulative/persistent viruses. The virus must pass through the vector's gut wall into the hemolymph and reach the salivary glands before it can be transmitted.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Vector-mediated viral transmission is classified based on the pathway the virus takes inside the insect's body.
In non-circulative transmission, the virus remains on the surface of the vector's mouthparts or foregut.
In circulative (persistent) transmission, the virus is ingested, crosses the gut wall into the hemolymph, circulates through the body, and enters the salivary glands to be discharged during feeding.

Step 2: Detailed Explanation:
Geminiviruses (family Geminiviridae, which includes Begomoviruses) are characterized by their twinned (geminate) icosahedral capsids containing single-stranded DNA.
These viruses are transmitted primarily by whiteflies (Bemisia tabaci) or leafhoppers.
The relationship between Geminiviruses and their vectors is persistent and circulative.
The insect must feed on the phloem of an infected plant for an extended period (acquisition access period) to ingest the virus.
The ingested virus particles then follow a circular path through the insect's digestive and circulatory systems:
\[ \text{Gut} \rightarrow \text{Hemolymph} \rightarrow \text{Salivary Glands} \]
This internal passage requires a latent period during which the insect cannot yet transmit the virus.
Once the virus reaches the salivary glands, the vector remains infective for a long period (often for the rest of its life), transmitting the virus during feeding.
Therefore, Geminiviruses are classified as circulative (persistent) viruses.

Step 3: Final Answer
Geminiviruses are transmitted in a circulative manner.