How do virus cause disease

Viruses make us sick by killing cells or disrupting cell function. Our bodies often respond with fever (heat inactivates many viruses), the secretion of a chemical called interferon (which blocks viruses from reproducing), or by marshaling the immune system's antibodies and other cells to target the invader.

Viruses are like hijackers. They invade living, normal cells and use those cells to multiply and produce other viruses like themselves. This can kill, damage, or change the cells and make you sick. Different viruses attack certain cells in your body such as your liver, respiratory system, or blood.

Viruses infect a host by introducing their genetic material into the cells and hijacking the cell's internal machinery to make more virus particles. With an active viral infection, a virus makes copies of itself and bursts the host cell (killing it) to set the newly-formed virus particles free.

Explanation:

Every virus-host relationship is different. In most cases, viruses do not cause any disease, and many are beneficial. For example, in mice a herpes virus prevents infection from the plague bacteria.

Although many viruses or bacteria are extremely helpful and we wouldn't be here without them, some live in our bodies and help us process and digest different foods, and without them we wouldn't be able to do that, we call these beneficial or symbiotic bacteria and viruses.

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