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The history of coronaviruses is an account of the discovery of the diseases caused by coronaviruses and the diseases they cause. It starts with the first report of a new type of upper-respiratory tract disease among chickens in North Dakota, U.S., in 1931.
The transmission of COVID-19 is the passing of coronavirus disease 2019 from person to person. COVID-19 is mainly transmitted when people breathe in air contaminated by droplets/aerosols and small airborne particles containing the virus. Infected people exhale those particles as they breathe, talk, cough, sneeze, or sing.
The first demonstration of phagocytosis as a property of leukocytes, the immune cells, was from the German zoologist Ernst Haeckel. [14] [15] In 1846, English physician Thomas Wharton Jones had discovered that a group of leucocytes, which he called "granule-cell" (later renamed and identified as eosinophil [16]), could change shape, the phenomenon later called amoeboid movement.
After tobacco mosaic was recognized as a virus disease, virus infections of many other plants were discovered. [34] The importance of tobacco mosaic virus in the history of viruses cannot be overstated. It was the first virus to be discovered, and the first to be crystallised and its structure shown in detail.
Infectious bronchitis virus (IBV), a type of coronavirus, causes avian infectious bronchitis. [131] The virus is of concern to the poultry industry because of the high mortality from infection, its rapid spread, and its effect on production. [127] The virus affects both meat production and egg production and causes substantial economic loss. [132]
Engulfment of material is facilitated by the actin-myosin contractile system. The phagosome is the organelle formed by phagocytosis of material. It then moves toward the centrosome of the phagocyte and is fused with lysosomes, forming a phagolysosome and leading to degradation. Progressively, the phagolysosome is acidified, activating ...
In the experiments, macaques infected with the virus developed the same symptoms as human SARS patients. [11] A virus very similar to SARS was discovered in late 2019. This virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the causative pathogen of COVID-19, the propagation of which started the COVID-19 pandemic. [12]
Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells. It is most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria.