These virus are very round. Their diameter is 10-250 nm. For example – Polio virus, Dengue virus, Flavi virus, Tomato bushystan virus, Corona virus, HIV, TGV, TIV etc.

Their shape is like a rod. This virus is 300 nm in length and 18 nm in width. For example, tobacco mosaic virus, mumps virus, alfalfa virus etc.

1. Rod virus: Their shape is like a rod. This virus is 300 nm in length and 18 nm in width. For example, tobacco mosaic virus, mumps virus, alfalfa virus etc.
2. Round virus: These virus are very round. Their diameter is 10-250 nm. For example – Polio virus, Dengue virus, Flavi virus, Tomato bushystan virus, Corona virus, HIV, TGV, TIV etc.
3. Cubical virus: All these virus are cubic in appearance. Their size is 100-350 nm. For example, vaccinia virus, herpes virus, wart virus, adenovirus etc. Dr. Siddiq Publications
4. Frog-shaped virus: All these virus have a head and tail like a frog. Their head is 95×65 nm and tail is 110×25 nm. Like- T2,T4,T6,T8 etc.
5. Egg-shaped virus: These virus look like eggs. For example, influenza virus.
6. Thread virus: They look like thin threads. For example – Dwarf virus of wheat, Streak virus of pea. Dr. Siddiq Publications
7. Cylindrical virus: They look like cylinders. For example, Ebola virus, pea streak virus etc.
8. Bullet-like virus: This virus looks like a bullet. For example, rhabdovirus.

Average diameter of virus is 8-300 nm. Typically plant virus are 17-2000 nm and animal virus 20-350 nm. The smallest plant virus is Satellite Tobacco Necrosis Virus, 8-17 nm. The largest plant virus is Citrus tristeza virus, which is 2000×12 nm. The smallest animal virus is the foot and mouth disease virus of cattle, which is 8-12 nm. The largest animal virus is the smallpox virus, which is 350×250×100 nm. Rhinovirus 10 nm, Polio virus 12 nm, Cauliflower mosaic virus 50 nm, Influenza virus 100 nm, Herpes virus 100-150 nm, Mumps virus 150-250 nm, Vaccinia and variola virus 280-300 nm, Bovine distemper virus 300 nm. over nm, tobacco mosaic virus 300×18 nm and potato X virus 500×10nm. Bit yellow virus 1250×40 nm.

Virus live in both living and inanimate environments. Plants, animals, bacteria, cyanobacteria, fungi, actinomycetes etc. are actively present in living organisms. Again, soil, water, air etc. remain passive everywhere. They are found in very cold water from high springs. 1 teaspoon of sea water contains 1 million virus.

The branch of biology that deals with the size, structure, propagation, pathogenesis, etc. of virus is called Virology. W. M. Stanley is called the father of virology. Dr. Siddiq Publications

According to biochemists, virus are inert substances. But according to microbiologists, virus are organisms. The properties of virus clearly prove that virus are neither living nor inanimate. For this reason, scientist A. Lowff commented in 1952 – A virus is a virus. It is neither a living organism nor a non-living chemical, but something in between. That is, a virus is a virus. It is neither living matter nor inert chemical matter. A virus is a type of organism between living and non-living things.
In 1962, scientists Stanley and Valens commented, virus are already like inanimate objects, but the moment they get a chance to attack a cell, the moment life is transmitted.

1. Virus are non-cellular components without protoplasm.
2. Virus are inert outside living cells as chemical particles or non-living crystals.
3. They are not self-reproducing. Cannot multiply outside the cell.
4. They can be aliquoted, centrifuged, spread and suspended.
5. They do not have cell wall, plasma membrane, mitochondria, lysosomes, ribosomes etc.
6. Physical growth of the virus does not occur.
7. They do not respond to any environmental stimuli.
8. Physiological functions- photosynthesis, respiration, movement, growth, osmosis etc. do not take place.
9. They have no metabolic enzymes and no nutritional activity.
10. Antibiotics cannot cause any reaction in the body of the virus.
11. Virus can resist acids, alkalis and salts.
12. They have no energy producing system.
13. They do not increase in size and do not respond to any external stimuli.
14. They cannot be controlled by antibiotics.

Biological characteristics of virus
1. Virus are composed of nucleic acids and proteins.
2. They can multiply inside living cells.
3. Genetic recombination occurs in this.
4. Variations and mutations occur and new strains are created.
5. Virus can cause disease in the host.
6. They are strictly obligate parasites.
7. The new virus created retains the characteristics of the original virus.
8. Their ability to adapt is extraordinary.
9. Their protein coat has antigenic properties.
10. Virus can spawn similar viruses.
11. Virus are capable of maintaining specific lineages.
12. Virus can synthesize proteins.
13. The nucleus or genetic material of the host cell is forcibly used for their multiplication.
14. They act on specific organs or organisms.
15. Virus contain the enzyme lysozyme.

1. In 1576, Charles Encluse was the first to realize the existence of viruses.
2. In 1796, scientist Edward Jenner mentioned the viral spring fever.
3. In 1886, Dutch scientist Adolf Mayer was the first to see tobacco leaf spot mosaic disease.
4. In 1892 Russian scientist Dmitri Ivanovsky proved that tobacco leaf germs can be filtered by antibacterial filters and that the germs are smaller than bacteria. He called it Virum. Hence Ivanovsky is called the discoverer of viruses.
5. In 1898, scientist Martinus Beijerinck named the tobacco leaf pathogen Tobacco Mosaic Virus (TMV).
6. In 1901, scientist Walter Reed first discovered the virus that causes human yellow fever or jaundice.
7. In 1931, German engineers Ernst Ruska and Max Knoll were the first to photograph viruses using an electron microscope.
8. In 1935, American scientist Wendel Meredith Stanley isolated TMV from tobacco. For this he won the Nobel Prize in 1946. Stanley isolated just one teaspoon of virus crystals from a ton of tobacco leaves. Dr. Siddiq Publications
9. In 1936-1937 scientists F. C. Bawden and N. W. Pirie proved that viruses are composed of nucleic acids and proteins.
10. In 1941, Bernal and Funkuchen obtained X-ray diffraction images of chelated viruses. Based on this image, Rosalind Franklin discovered the complete structure of the virus in 1955.
11. In 1951, R. S. Shafferman and M. E. Morris discovered cyanophages that destroy cyanobacteria.
12. In 1952 scientist A. Lwoff said – A virus is a virus. It is neither a living organism nor a non-living chemical, but something in between. That is, a virus is a virus. It is neither living matter nor inert chemical matter. A virus is a type of organism between living and non-living things.
14. In 1965, scientist Howard Temin discovered retroviruses.
15. In 1984, scientist Gallow discovered HIV, the virus that causes the deadly human disease AIDS. Later, successive scientists Gallo, Sinousi and Montanier discovered two types of HIV.
16. In 1989, scientist Hervey J. Alter discovered the silent killer hepatitis C.
17. In late 2019, the Novel Corona Virus or Covid-19 was discovered.
13. In 1963, scientist Baruch Blumberg discovered Hepatitis-B. Dr. Siddiq Publications