In the 1880s, Louis Pasteur developed a method of weakening viruses. The weakened viruses could be injected into healthy individuals. How is this method effective in fighting viral diseases? * 1.The immune system develops antibodies in response to the weakened viruses.

2.The weakened viruses attach to unaffected viruses in the host and interrupt the viral reproductive cycle.

3.The rate of genetic mutation in the host is decreased due to the introduction of weakened viruses

4.Weakened viruses are unable to enter the host organism.