Economic Importance of Viruses

Virus is an infectious agent with microscopic size that needs living cells of plants, animals or bacteria to multiply. The name virus is derived from Latin word meaning “poison” or “slimy liquid”.  

They are not animals, plants or bacteria and they can`t do metabolic process without a host cells. The body of virus contains nucleic acid (DNA or RNA) and protein. Hence, there are two types of viruses such as DNA virus and RNA virus.

Image of DNA Viruses

Classification of DNA Virus

image of RNA viruses

Classification of RNA Virus

Virus influence the global biogeochemical cycles and they can transfer their genetic material into a host cell when they attach with host cell.

They produce diseases in an organism using their different mechanisms. Some viruses produce chronic infections to the hosts such as hepatitis B virus and hepatitis C virus infections.

If people chronically infected then they serve as reservoirs of infectious virus and they are known as carriers. In this case, the disease is called endemic if the population with a high proportion of carriers.

Importance of Viruses

Viruses have both harmful and beneficial roles in human life. Actually no virus directly involves in human welfare, in most cases scientists use them as beneficiary agents in different fields.

Harmful Effects of Viruses

A vast number of viruses cause human and animal diseases. Some viruses are epidemic which spreads rapidly to many people and some viruses are pandemic which spread diseases worldwide. COVID-19 (corona virus disease) is very life threatening disease that already has taken the lives of nearly few lakhs people worldwide. In 2003, the severe acute respiratory syndrome (SARS) also took the lives of nearly 800 people worldwide.

Besides, a vast number of viruses cause plant diseases as rice tungro baciliform virus (RTBV), tobacco mosaic virus (TMV), tomato/papaya ring spot virus, tomato leaf curl, potato leaf roll virus, etc.

The following table shows the various virus diseases in man, animals and plants:


Name of diseases


Influenza virus



Herpes virus








Variola virus

Small pox


Rubeola virus



Polio virus



Rabies virus



Yellow fever virus

Yellow fever


Flavi virus



Vaccinia virus

Cow pox


Foot and mouth virus

Foot and mouth disease


Papaya ring spot virus

Papaya ring spot disease


Tobacco mosaic virus

Tobacco mosaic disease


Bean mosaic virus

Bean mosaic disease


Tungro virus

Tungro disease of rice


Bushystant virus

Bushystant disease of tomato


Bancy top virus

Bancy top disease of banana


Some morphological and pathogenic characteristics of the major hepatitis viruses:


Virus Name

Hepatitis A virus (HAV)

Hepatitis B virus (HBV)

Hepatitis C virus (HCV)


27 nm

42 nm


Nucleic acid





Endemic and epidemic



Incubation period

2-7 weeks

1-6 months

2-8 weeks


Fever, Gastro-intestinal tract disorders

Fever, rash, arthritis

Fever, rash, arthritis


1 in 10




Acute, short

Gradual, chronic

Acute to chronic



Chronic active hepatitis, hepatic cancer

Chronic inflammation, cirrhosis

Poultry birds are also severely infected by viruses. The avian influenza H5N1 (hemagglutinin type 5 and Neuraminidase type1) produces birds flu and the poultry sector.

The grasseric disease of silkworm (Bombyx mori) is caused by a nuclear polyhedrosis virus (NPV), sometime which is the only reason of declination of silk industry.

Besides these, bacteriophases attack the nitrogen fixing bacteria of the soil and are responsible for reducing fertility of the soil.

Viruses are also used as biological warfare and weapons in many countries. Viruses are tiny but they have the ability to produce diseases which can cause death and damage to huge populations in epidemics and pandemics.

Beneficial Effect of Viruses

There are many industrial uses of viruses. Viruses are used in preparation of sera and vaccines to be used against diseases like rabeis, polio, hepatitis B, papillomavirus, etc. The multiplication of viruses in bactereial cells is also utilized in the production of antibodies.  It is used in various pharmaceutical products such as proteins, vaccine, antigens and antibodies.

Viruses are also used in biological studies. They have gained a prominent position in world because of their value as biological research tools.

They are broadly used in research in the field of genetic engineering, molecular biology and medicine due to their capacity to fast reproduction and plainness structure.

Viruses are used in bacteriophage therapy. Bacteriophages have been researched for their use in therapy.

There are many uses of viruses in medicine. In this case, it is being used as vectors or carriers that take the required material for treatment of a disease to various target cells.

In the life science, it plays an important role to understand the basic mechanisms of molecular genetics. It is also used in genetic engineering for the production of cloning.

It is used for gene therapy. In this case, viral genes are replaced by the human gene.

Viruses are used in biological control by human in eradicating pests like insects (by NPV) and in controlling the population of organisms such as rabbits by inducing viral infection.

The viruses also played a central role in the early evolution, before the diversification of bacterial, archaea and eukaryotes, at the time of the last universal common ancestor of life on earth. Viruses are still one of the largest reservoirs of unexplored genetic diversity on earth.

Viruses are also used in aquatic environment to recycling carbon. About one million of viruses are found in one teaspoon of seawater. Among them, majority are bacteriophages. They are not harmful to animals and plants and they play an important role to regulate the freshwater and saltwater ecosystem by destroying bacteria and recycling carbon in the aquatic ecosystem.

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