What are the various beneficial activities of living and non-living virus?

Beneficial Activities of Virus:

It is a general concept that iron cuts iron. Keeping this view under consideration many harmful insects have been killed by using virus. The mouth disease of rabbit is cured by using Myxonea virus. It kills pests. Similarly, the caterpiller of Lucerne grass can be killed by using polyhedral virus. Kotochalia insect lives on Acacia plants and can be killed with the help of virus. Neodiprivn fly is harmful insect. The larva of this insect can be killed by using the solution of virus by spraying on the plants. The solution of viruses is also used as spray on wooden windows and furnitures.

Nature of Virus:

Several arguments have been put forth by various scientists about the nature of virus. Some scientists regard them as living while others call them non-living and consider them of different nature. Following are properties regarding the nature of virus:

1. Non-living characters of viruses :

(i) They can be obtained in the forms of crystals.

(ii) Outside the host cells they are like inert chemicals.

(iii) Metabolic activities like respiration, photosynthesis are not exhibited by them.

(iv) Absence of protoplasm and enzyme system.

2. Living characters of viruses :

(i) Virus particles actively multiply in the living cells of the host and produce particles of its own type.

(ii) They are stimulated by temperature and chemicals.

(iii) They cause diseases hi plants, animals and bacteria.

(iv) They contain genetic material.

(v) They have RNA or DMA and proteins as their constituents.

(vi) There are some specific viruses which infect specific hosts.

(vii) Viruses exhibit different shapes.

(viii) They exhibit multiplication and mutation.

(ix) Each virus particle has nucleic acid, which is surrounded by a protein sheath.

(x) Sex organs are absent.

(xi) they are regarded as biological atom.

Thus, viruses have both living and non-living characters. They are very tiny in size and can pass through bacteria-proof filters. They reproduce only in living cells. Chemically, they consist of nucleic acid enveloped by protein sheath.

According to virus theory, viruses are intracellular obligate parasites, which multiply only in living hosts. Prior to this theory scientists proposed mycoplasma theory, bacterial, theory, contagium theory, non­living toxin theory, oxidizing enzyme theory and protozoan theory about the nature of viruses, but in recent times. Virus theory has been recognised, which has the following special features:

1. Viruses cannot be seen with ordinary microscope.

2. They cannot be cultured on artificial media.

3. They are so minute that they pass through bacteria-proof filters.

4. They produce specific symptoms in the host.

5. They are affected by temperature, chemicals and humidity.

6. They become inactive due to chemotherapy and thermotherapy.

7. They can produce new strains in nature.

8. They act as living entities in host tissues.

9. They are intracellular and obligate parasites and also called ‘geneparasites’.