Are bacteria and viruses animals or plants?

Bacteria are single-cell organisms without the cell nucleus. Viruses are only nucleic acid molecules in a protein coat. They belong neither to the animals, which are multicellular organisms, nor to the plants, which always have a cell nucleus. While most viruses make humans, animals, and plants sick, many bacteria are good for humans. For example, bacteria in the gastrointestinal tract help in digestion, whereas others like salmonella cause diseases.