Teddies Talks Biology - Issue 9

Daniela Olinic—LVI

Viruses are microscopic parasites that cannot reproduce by themselves. They are known to cause contagion, such as the COVID - 19 pandemic, the Ebola outbreak from 2014 in West Afri- ca and the H1N1 pandemic. Once a virus infects a cell, it can control the cell machinery and cause it to produce more viruses. They have either DNA or RNA as genetic material. The virus particle, or virion, is made of a nucleic acid and an outer shell protein. Viruses can also be use- ful research tools for scientists as they help better our understanding of cellular processes such as protein synthesis. In case of viral infection, organisms generate a defense by triggering an immune response. There are 3 types of immunity: innate, adaptive, and passive. Innate immunity, also known as natural immunity, is the one anyone is born with, such as the skin as a barrier against germs or other foreign invaders. The adaptive, or active immune system develops through immuniza- tions or being exposed to disease during our lives. Passive immunity is a short - time source of immunity, like the antibodies a baby gets from the mother ’ s breast milk.

Innate immunity is a first line defense against viral infection or replication and is active even before the infection begins. The innate immune system responds very quickly, within minutes or hours after infection. Its main ability is to recognize viruses as foreign. This is done through

pattern recognition receptors that distin- guish the viral proteins and nucleic acids. These proteins are present either in the cell cytoplasm or on cell membranes, where they are recognized by the invaded cells. The presence of cytokines is also an early indication of viral infection within the host cell. Cytokines are secreted by the infected cells. They function by binding with other cells locally, but also by engaging neighbor- ing cells. These cells produce cellular pro- teins which have antiviral activities. When cytokines enter circulation, they cause typi- cal symptoms of viral infections, such as fever, lethargy, and loss of appetite.

Teddies Talks Biology I Issue 9 I June 2021

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