Compare and contrast the ways in which animal, plant, and bacterial viruses gain entry into their host cells

Question

What will be an ideal response?

Answer 1

Because cells have different types of barriers against the outside world, viruses have evolved different ways of breaching these barriers. For example, viruses cannot easily invade cells that have rigid, protective cell walls (such as plant and bacterial cells). Viruses that infect these cells gain entry by direct injection (as observed in bacteriophage T4), by taking advantage of damage to the cell wall (as with some plant viruses), or by enlisting the aid of insects that are themselves parasites (as with some other plant viruses). In contrast, animal cells have no cell wall; therefore, animal viruses employ three basic strategies to enter through the flexible cytoplasmic membrane. Some animal viruses directly penetrate this membrane (either the entire virus or just its genome), whereas other viruses take advantage of natural cellular processes such as phagocytosis to gain entry into the cell. Enveloped animal viruses also can use the process of membrane fusion to get inside an animal cell.