Fig. 1.

IAV replication blocks in mouse and human macrophages. Various experimental models have been used to describe multiple blocks to productive IAV replication in mouse (a) and human (b) macrophages. The IAV replication cycle is depicted with the points at which macrophages restrict virus replication indicated by a red ‘X’. (a) In mouse macrophages, four blocks have been shown to exist. (1) Inefficient attachment and internalization. (2) An inability to successfully escape from the cellular endosome mediated by the acid stability of the viral HA protein. (3) Translation of late viral proteins. (4) Defective assembly and budding of infectious virions following protein translation. (b) In human macrophages only the late blocks have been described. (1) Dysfunctional nucleocytoplasmic trafficking of viral proteins. (2) Defective assembly and budding of infectious virions.