animal/ bacterial viruses

Bacterial and animal viruses both attach to their target cell through cellular receptors.

Bacterial viruses are called bacteriophages (or phages for short). They attach to the cell membrane and release their content.

Animal viruses enter via many routes, i.e. through respiratory tract, gastrointestinal tract, etc. I wrote a large article on this topic; it can be found on this website:

http://www.ppdictionary.com/viruses.htm

Basically, animal viruses enter host cells by a process called endocytosis. The genetic material of bacteria are injected as opposed to endocytozed. Plant viruses, by contrast, enter through wounds in the cell's outer coverings.