Simplify the following text for a Grade 11 native English-speaking person.
Original: Some viruses can `` hide '' within another cell , either to evade the host cell defenses or immune system , or simply because it is not in the best interest of the virus to continually replicate .
Simplified: Some viruses can `` hide '' inside another cell , either to defend itself against the host cell defenses or immune system , or because it is not in the best interest of the virus to make more copies at the time .