<unk>  is the range of cells and<unk> s of a host that support growth of a particular virus or bacterium. Some bacteria and viruses have a broad<unk>  and can infect many types of cells and<unk> s. Other viruses may infect primarily a single<unk> . For example, rabies virus affects primarily neuronal<unk> .
Tissue tropism
Histocompatibility
Antigenicity
Thermostability
Antimicrobial spectrum
Immunity 
Social immunity
Drug resistance