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Virology is the study of viruses and virus-like entities, covering taxonomy, disease-causing qualities, cultivation, and genetics, among other things. Viruses have characteristics that distinguish them from other microorganisms. Viruses reproduce quickly, and their structure differs significantly from that of other tiny particles. Virology has grown to be one of the most important sub-disciplines of microbiology, and it is frequently lumped in with microbiology and pathology. Martinus Beijerinck is often called the Father of Virology.
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Key Takeaways: Virology, Virus, Microbiology, Viral diseases, Infections
What is Virology?
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Virology is the branch of microbiology that mainly deals with the study of various types of viruses, and virus-like agents. It mainly focuses on aspects such as their immunity, the ability to destroy or infect the host cells, their evolution, classification, structure, composition, several ways of infecting, different ways of culturing them, their use in the laboratory, various methods to isolate them and their physiology. The first viruses found were the tobacco mosaic virus, foot and mouth disease virus, and yellow fever virus.
Characteristics of a Virus
Viruses are infectious agents that have both living and nonliving features. Viruses have diverse chemical compositions depending on which virus family they belong to. The virion is made up of viral structural proteins and nucleic acid in the simplest of viruses; however, when dealing with enveloped viruses, the situation becomes more complicated. The latter types of viruses mature by budding through various cellular membranes that have been altered by viral protein insertion.
- They multiply quickly and only in the presence of live host cells.
- They can mutate.
- They don't have cytoplasm or cellular organelles, and they're not cells.
- They don't multiply or divide.
- Within the infected host cell, new viruses are produced and assembled.
- The majority of viruses only have one of the two genetic components, DNA or RNA.
- All viruses are obligate intracellular molecular parasites.
- A second inviolate characteristic of viruses is that they do not reproduce through binary fission, which is an asexual reproduction technique in which pre-existing cells split into two identical daughter cells.
Virus
Types of Viruses
Based on the general composition (nucleic acid) – RNA and DNA, the viruses are classified into two categories.
RNA Virus
The RNA virus contains RNA as its genetic material include either single-stranded or double-stranded RNAs. Colds, hepatitis, polio, etc. are some of the diseases produced by the RNA virus in humans. The RNA virus includes all plant viruses and has a greater mutation rate.
The double-stranded RNA virus is made up of several different viruses that change greatly depending on the host-virus (fungi, bacteria, genome, virion, and organization)
A single-stranded RNA is classified according to whether it has positive or negative senses.
DNA Virus
DNA virus is a type of virus that has DNA as its genetic material. They are DNA-dependent and need DNA polymerase to replicate. They are normally double-stranded DNA, although they can also be single-stranded DNA in some situations.
Bacteriophages, cyanophages, and the majority of animal viruses are DNA viruses. Depending on the host and genetic material. Viruses are divided into three categories.
Animal viruses - Animal viruses are viruses that infect and survive inside animal cells, including humans.
Plant viruses – These viruses infect plants and are hence known as plant viruses.
Bacteriophage - Bacteriophages are viruses that infiltrate and infect bacterial cells.
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Viral Diseases
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Viral diseases are infections caused by microbes called viruses. Viruses can be found in a number of shapes and sizes that can lead to a wide range of diseases. The common cold which is caused by viruses is the most common type of viral disease which affects the upper respiratory tract. Other viral infections that are common include:
- Chickenpox
- The flu is a contagious illness (influenza)
- Herpes
- HIV/AIDS
- HPV
- Mononucleosis contagious
- Mumps, measles, and rubella are all contagious diseases.
A virus tends to multiply when it enters a human body and becomes infectious and spreads from person to person. Viruses can spread from person to person in a variety of ways, including:
- Inhaling virus-infected airborne droplets
- Eating virus-infected food or drinking virus-infected water
- Having sexual contact with someone who has a sexually transmitted virus.
- A virus host, such as a mosquito, tick, or field mouse, transmits the virus from person to person in an indirect manner.
- Contacting virus-infected surfaces or bodily fluids
Molecular Virology, Clinical Virology and Veterinary Virology
Molecular Virology
The study of viruses at the molecular level is referred to as molecular virology. It's the study of how cellular proteins interact with their hosts, whether they're human, plant, or animal. Molecular testing is being considered by lab teams as the next trend. The use of molecular diagnostics has become the new standard. Automated systems give doctors the tools they need to deliver accurate and sensitive results, which can enhance patient care and outcomes by allowing for faster diagnosis.
Clinical and Veterinary Virology
Clinical virology is the study of viruses that cause human pathologies in the science of virology. Veterinary virology is a branch of virology concerned with the prevention and treatment of animal viruses, viral agents, and other viral illnesses. For example, prion disorders, artery virus, Pesti virus, and other viruses. In clinical virology, veterinary virology is also essential.
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Things to Remember
- Virology is the study of viruses and virus-like entities, covering taxonomy, disease-causing qualities, cultivation, and genetics, among other things.
- Viruses are small non-cellular entities made up of genetic material and proteins that can infect live cells. They are members of the viridae family of the genus virus.
- They lack a nucleus and a well-organized cell structure.
- They usually include one or two strands of DNA or RNA and are protected by a protein coat known as the capsid.
- Based on nucleic acid, they are classified into two types, RNA and DNA virus.
Sample Questions
Ques. Name any four common viral diseases? (4 marks)
Ans: The four common viral diseases are
AIDS (acquired immunodeficiency syndrome) is one of the four most frequent viral infections. The human immunodeficiency virus (HIV) causes this disease.
Herpes- The herpes simplex virus causes herpes, which is a viral ailment.
Smallpox- Smallpox is an infectious disease caused by the variola virus. Previously it was contagious, but it is no longer contagious.
The common cold, often known as a cold, is a contagious illness that affects people of all ages. It is a viral infection that affects the respiratory tract, particularly the nasal area and throat.
Ques. Give a brief overview of viruses, including their structure and genetic material. (4 marks)
Ans: Viruses are non-cellular organisms that have a tiny infectious agent and are distinguished by their inert crystalline structure. In viruses, the genetic material is either DNA or RNA. AIDS, mumps, smallpox, herpes, and other viral infections are widespread. Viruses do not qualify as 'living' because they lack a cell structure. When they enter a living cell, they take over the host cell's machinery and begin multiplying and destroying the host. The viruses include genetic material in the form of DNA or RNA. A virus cannot contain both DNA and RNA. It's a nucleoprotein with infectious genetic material.
The following components make up the entire virus:
Core- It is a nucleic acid that can be either DNA or RNA, but not both at the same time. Capsid- It is a protein-based outer covering for the genetic material. It is made up of numerous identical subunits called capsomeres.
Envelope- the outermost covering of some viruses, such as HIV, herpes, and others, but it is absent from others.
Ques. Could it be possible for a virus to cause infection? (3 marks)
Ans: Infections are caused by viruses. They're minute germs made of genetic material that can spread infectious diseases including the common cold, flu, and warts. They can even cause serious infections like HIV/AIDS, smallpox, Ebola, and COVID19, a new coronavirus. Viruses infect regular living cells and use them to proliferate and make other viruses like themselves. This buildup can make you sick, harm or modify the structure of your cells, and make you sick. Viruses assault cells in the body, including those in the liver, lungs, and blood. The virus is fought by your immune system. Vaccines are beneficial, but antibiotics are ineffective.
Ques. Could it be possible for a virus to cause infection? (3 marks)
Ans: Infections are caused by viruses. They're minute germs made of genetic material that can spread infectious diseases including the common cold, flu, and warts. Viruses infect regular living cells and use them to proliferate and make other viruses like themselves. This buildup can make you sick, harm or modify the structure of your cells, and make you sick. Viruses assault cells in the body, including those in the liver, lungs, and blood. The virus is fought by your immune system. Vaccines are beneficial, but antibiotics are ineffective.
Ques. Describe the bacteriophage structure. (3 marks)
Ans: Structure of Bacteriophages
A polyhedral head, a shirt collar, and a helical tail make up the bacteriophage.
The head is made up of 2000 capsomeres that contain double-stranded DNA.
The tail is made up of an inner hollow tube that is encased in a contractile sheath that has 24 annular rings. A basal plate with tail fibres at each corner makes up the distal end. With the help of these tail fibres, the bacteriophage adheres to the bacteria.
Ques. What Happens When Viruses, RNA, and DNA Interact? (3 marks)
Ans: Ribonucleic acid is ribonucleic acid, while deoxyribonucleic acid or proteins is deoxyribonucleic acid. Living creatures' cells have DNA in their nuclei for the most part. The genetic material is stored in the nucleus. Viruses carry genes responsible for the encoding of certain proteins in either DNA or RNA. A virus is nothing more than a collection of dead protein cells. The DNA or RNA of different types of viruses differs as well. This distinction allows viruses to be identified. Poxviruses and herpes have double-stranded DNA that is enclosed. Polyomaviruses' double-stranded DNA does not have an enveloped presence.
Ques. What is molecular virology? (3 marks)
Ans. The study of viruses at the molecular level is referred to as molecular virology. It's the study of how cellular proteins interact with their hosts, whether they're human, plant, or animal. Molecular testing is being considered by lab teams as the next trend. The use of molecular diagnostics has become the new standard. Automated systems give doctors the tools they need to deliver accurate and sensitive results, which can enhance patient care and outcomes by allowing for faster diagnosis.
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