Figure 1.

SV40 structure and entry pathway. (A) Diagram of the SV40 structure. (B) To begin the entry process, SV40 binds to a host cell receptor at the plasma membrane called ganglioside GM1 (step 1). This event initiates receptor-mediated endocytosis that targets the virus to the endosomes. From the endosomes, SV40 is targeted to the ER (step 2) from where it breaches the ER membrane to escape into the cytosol (step 3). Upon reaching the cytosol, the virus is further mobilized into the nucleus (step 4) where its genome is released. Transcription and replication of the viral genome then lead to lytic infection or cellular transformation.