The coronavirus is — like any other virus — not much more than a shell around genetic material and a few proteins. To replicate, it needs a host in the form of a living cell. Once infected, this cell does what the virus commands it to do: copy information, assemble it, release it.
But this does not go unnoticed. Within a few minutes, the body's immune defense system intervenes with its innate response: Granulocytes, scavenger cells and killer cells from the blood and lymphatic system stream in to fight the virus. They are supported by numerous plasma proteins that either act as messengers or help to destroy the virus.
For many viruses and bacteria, this initial activity of the immune system is already sufficient to fight an intruder. It often happens very quickly and efficiently. We often notice only small signs that the system is working: We have a cold, a fever.
any virus infection in vertebrates would results in two forms of immune response ,at first innate response which involve the production of interferons and stimulation of natural killer (lymphocyte),when the infection proceeds the adaptive immmune response have been triggered which itself has to types the humoralproduction of antibodies) and cell mediated response (synthesis of specific cytotoxic t lymphocyte that kill the infected cells).