Answer:
cells
Step-by-step explanation:
Viruses are not composed of cells (unlike bacteria). They are acellular organisms formed only by a protein capsule and a nucleic acid, DNA or RNA. For this reason, scientists have wondered for many years whether viruses could be considered living beings or not.
Despite being formed by cells, viruses need cells for their multiplication, for this reason they are considered obligatory parasites, since they appropriate the cells of a host.