One way the body fights invaders is by increasing the body temperature, or running a fever. give a brief explanation as to why that defensive technique works against some viruses or bacteria.
writing assignment

An increased body temperature made changes to the T-cell membrane to fight certain temperature sensitive viruses or bacteria.

Explanation:

According to medical science, having fever or an increased  body temperature helps the human body to fight certain temperature sensitive bacteria or viruses.

An experiment performed by the Chinese scientist, Jian Feng Chen of Shanghai Institute of Biochemistry on mice showed that the injected high temperature in the body of the mice stimulated the T-cell membrane which started secreting heat-shock protein or Hsps, which fights stress.  

This study showed that the raised temperature triggers the body immune system to fight a virus or bacteria caused infection.

it is definitely false.