Courses for Kids
Free study material
Free LIVE classes


share icon
share icon
Join Vedantu’s FREE Mastercalss

Introduction to Virology

In the field of microbiology, Virology primarily deals with the study of viruses as well as virus-like particles. The research and observations are based on the characteristics, classifications, and the relationship of the viruses with their hosts. Viruses are unique traits that set them apart from others in the microbiology world.

You know by now that viruses multiply fast and their structure is also quite different from other microscopic particles. Viruses are microscopic parasites that cannot thrive. They are capable of latching on to host cells and getting inside them. Here we will discuss virology meaning and the principles of virology.


What is Virology?

Virology came forward as a science at the end of the 19th century. It relates to the study of microscopic agents responsible for plant and animal infectious diseases. Tobacco mosaic virus, foot and mouth disease virus, and yellow fever virus were among the first viruses discovered. Approximately 30 years later (around the year 1927) there came forward a list of about three dozen diseases that were thought to be caused by viruses.

Viruses were mainly placed together according to their visual symptoms and modes of transmission. It was the first phase of Virology. Then came the electron microscope in the late 1930s. Viruses came to be known as particles. It did not take long to recognise these particles as nucleic acid and proteins. Thus, proteins and nucleic acids were firmly established as components of animal and plant viruses.

Over time, the introduction of cultured cells for in-vitro propagation of viruses accelerated the pace of virus discovery. There arose a need to classify and name groups of viruses. Biology, genetics, and morphology, and physicochemical properties of virus components came into the scene.  Around 2012, the introduction of extremely sensitive and high-sequencing technologies made dramatic changes. The world saw a multitude of novel viruses, most of them known by their genomic (hereditary) formation.

The classification of the virus according to their genome (hereditary) sequence may be in consideration as the ongoing phase of virus taxonomy or classification.


Characteristics of a Virus

As you know viruses are infectious agents with living and nonliving characteristics. A virus can infect animals, plants, and other microorganisms.  Viruses that infect only bacteria are known as bacteriophages.  Viruses that infect fungi are known as mycophages. And, the virus that attacks other viruses is known as virophages.  Characteristics of viruses can be living as well as non - living.

The Living Characteristics of Viruses are:

  • They reproduce at a fast rate, only in living host cells.  

  • They can mutate

The Non - Living Characteristics of Viruses are: 

  • They are not cells, contain no cytoplasm or cellular organelles. 

  • They don’t grow and divide. 

  • New viruses are synthesized and assembled within the infected host cell. 

  • The majority of viruses possess either DNA or RNA, not both.


Types of Virus 

There are only two categories of viruses according to general composition- RNA and DNA.

RNA Virus - it is that type of virus that has RNA as its genetic material. It can be a single-stranded or double-stranded RNA. Diseases caused by the RNA virus include common cold, polio, hepatitis, influenza, measles, and SARS.  Plant virus is an example of an RNA virus.

DNA Virus - It is a type of virus that has DNA as its genetic material. They depend on the DNA and replicate using the DNA polymerase. They are sometimes double-stranded. In some cases, they can be single-stranded. Most of the animal viruses, bacteriophages, cyanophages, and animal viruses are examples of DNA viruses.

Based on genetic material, and type of host, we can say that there are three types of viruses - Animal virus, Plant virus, and Bacteriophages.


Molecular Virology

Molecular virology refers to the study of viruses at the molecular level. It involves the analysis of genes and gene products. It refers to the study of the interaction with the host- human, plant or animal- cellular proteins. Teams working in the lab think about molecular testing as the trend in the future. Molecular diagnostics have become the new normal. The introduction of automated systems provides the tools necessary to report accurate and sensitive results to clinicians – it can improve patient care and outcomes by correct and fast diagnosis.



The principles of virology state that a virus is made up of genetic material, known as either DNA or RNA. It is essential to understand that infections are of medical and veterinary significance. Virology has become one of the most important sub-disciplines of microbiology. It has allowed researchers to discover treatments and cures for the diseases that they cause.  Besides, virology is in use for pharmaceutical purposes also. Get the study materials from the Vedantu website.

Last updated date: 26th Sep 2023
Total views: 359.1k
Views today: 4.59k
Want to read offline? download full PDF here
Download full PDF
Is this page helpful?

FAQs on Virology

1. Can a Virus Cause Infection?

Viruses cause infections. They are very tiny microscopic germs made of genetic material and can cause common infectious diseases such as common cold, flu, and warts. They can even cause severe illnesses such as HIV/AIDS, smallpox, Ebola, and the novel coronavirus or COVID19. What viruses do is enter normal living cells, and use those cells to multiply and produce other viruses like themselves. This accumulation can make you sick, damage or change the cellular structure and make you sick. Different viruses attack cells in the body such as the liver, respiratory system, and blood. Your immune system fights the virus. Vaccines help, but antibiotics don’t work.

2. What is the Interaction Between Virus, RNA and DNA?

RNA is ribonucleic acid and DNA is deoxyribonucleic acid or proteins. For most of the part, the cells of living organisms have DNA in their nucleus. The nucleus carries genetic material. Viruses either carry DNA or RNA with the genes that are responsible for the encoding of specific proteins. Note that a virus is nothing but dead protein cells. The DNA or RNA between different types of viruses is also different. This difference allows the identification of viruses. Poxviruses and herpes have enveloped double-stranded DNA. The double-stranded DNA of Polyomaviruses does not have an enveloped presence.

3. In what ways is a Virus different from other organisms?

An analysis of their characteristics 

  • It can normally be identified and differentiated by the electron microscope, NMR spectroscopy or X-ray crystallography because it is a tiny complex infectious particle that cannot be seen with ordinary microscopes.

  • The virus can grow only on natural media. It can always filter and pass through natural or biological filters. 

  • This planet is a very diverse place and viruses can be found everywhere, in bacteria, plants, animals, and humans as well.

  •  Viruses are strictly intracellular parasites, which makes them the most important of all viruses. 

  • Its metabolism depends only on the metabolic machinery of its host cell and has no metabolic properties of its own.

  • Viral infections are resistant to antibiotics: Viruses are immune to antibiotics.

4. How can Viruses Affect Humans?

Viruses that affect humans are

  • There are five types of poxviruses: Pox, Parvo, Herpes, Paramyxo, Orthomyxo, and Popova.

  • Diseases caused by these viruses are listed below. 

  • Virus transmission through the respiratory tract (droplet infection), smallpox, chickenpox (pox virus). 

  • The vaccine for German measles is rubella (toga). Rubeola (paramyxo) causes measles. The disease is transmitted through the respiratory tract. 

  • Human papillomaviruses (HPVs) cause warts, epithelial growth, and skin lesions (gestational and plantar warts).

  • Poliomyelitis is caused by the poliovirus. Transmission through faecal and contaminated water

5. How do Viruses get Sequenced?

In virology, sequencing is one of the main tools to identify and study viruses, since most viruses are too small to be seen with a light microscope. Sequencing of viruses in basic and clinical research, molecular epidemiology of viral pathogens, and drug resistance testing using conventional Sanger sequencing and next-generation sequencing (NGS) are all performed using these methods. The GenBank database contains more than 2.3 million unique viral sequences. Non-directed genome sequencing has recently gained popularity over traditional Sanger sequencing as the primary method for generating viral genomes. Download the free pdf study notes from

Competitive Exams after 12th Science