Virus:
……….. is a small, simple infectious agent.
It can be defined as a non-cellular, infectious entity made up of genetic material and protein that can invade and reproduce only within the living cells of bacteria, plants and animals. The nucleic acid of viruses, which serves as genetic material, is either DNA or RNA(a small piece of genetic information ,DNA or RNA) inside a protective protein coating called capsid. Viral infections are any illness you get from virus and this virus uses the cells of living organisms to reproduce or
make copies of themselves in a process called replication. Since human cells have the
machinery needed to make more cells and virus do not, they have to break into cells of living
organisms to be able to replicate and have higher load which makes its carrier sick. The Low
risk viruses go away on their own, while the high risk viruses cause life-threatening or chronic
illness. Viruses usually enter the body of its host through the mucous membranes(inner linings ) of organs such as eyes, nose, mouth, stomach, penis, vagina and anus. Some viruses also get in
through a break or a cut on the skin or from a bite from a mosquito or tick and other virus
transmitting vectors. Viruses can cause several illness such as respiratory illnesses, sexually
transmitted infections (STIs), skin conditions and many other kinds of illnesses. Some commonly known viral infections include: Common cold, The flu (influenza), COVID-19, Respiratory
syncytial virus infection, Chickenpox, Measles, HIV/AIDS, Human Papillomavirus Virus(Warts on the body, genital etc), Herpes simplex (Herpes Simplex Virus), Poliomyelitis, Rabies, Mpox, Zika virus infection, Hepatitis etc.
Characteristics of Virus.
Virus is a sub-microscopic particle that lives by infecting the cells of a living organism. When
compared with prokaryotic these are smaller in size and range from 20-300 nm. Individual virus
is known as a Virion. Viruses do not have specialised machinery such as cell membranes,
nucleus, mitochondria, endoplasmic reticulum, and many other cell organelles required for
growth, reproduction, energy production, maintaining homeostasis etc. Viruses can replicate only by infecting a host cell. Viruses cannot be classified either a living organism or non-living
organism. This is due to the fact that they possess certain defining characteristic features of
living organisms and non-living entities. Viruses are significantly smaller than bacteria. They
exist outside of the living cell as active particles surrounded by a protein coat.
Virus can replicate in plant, animal as well as bacteria cells etc. It enters and attaches itself to a
specific host cell and injects its genetic material and reproduces by using the host genetic
material and finally the host cell splits open, releasing the new viruses.
CLASSIFICATIONT OF VIRUS
Viruses are classified based on their different criteria;
