Figure 1.

Mechanisms of introduction of positive-sense viral RNA into cells. (A) Depicts infection of a host cell with a natural EEEV particle. The virus entry protein, E2, binds to a host receptor (1) that allows for entry into the host cell via endocytosis (2). Within the endosome, the pH decreases, allowing for conformational changes of the entry and fusion proteins, enabling the fusion protein, E1, to create a pore within the endosome, resulting in the release of the viral capsid into the cytosol (3). The capsid is then disassembled by the host ribosome, and viral genomic RNA is released, transcribed, and translated into viral proteins (4). Structural proteins and genomic RNA then assemble and bud at the peripheral membrane to form progeny virions. (B) Depicts intentional introduction of the viral genomic RNA via electroporation for comparison. (1) Electroporation creates pores in the peripheral membrane, (2) allowing artificially introduced EEEV genomic RNA to enter the cell without the viral structural proteins typically needed for entry and fusion steps. (3) Replication, transcription, and translation then occur in the same manner as natural virus infection, (4) producing progeny virions that can infect and replicate in the same manner as 1A.