Induction of membrane proliferation by poliovirus proteins 2C and 2BC

Poliovirus infection leads to the appearance of a number of cytoplasmic vacuoles involved in the replication of virus genomes. To characterize the viral proteins involved in membrane proliferation different poliovirus proteins have been expressed in HeLa cells. Two recombinant vaccinia viruses have been obtained that express poliovirus protein 2C, one under the 5' untranslated (UTR) sequence of poliovirus and another under the leader region of EMC virus. Expression of 2C was very efficient in both cases, although better results were obtained when poliovirus 2C was expressed under the 5'UTR sequence of EMC virus. Transient expression of poliovirus proteins 2B, 2C or 2BC placed under a T7 promoter was analyzed using a recombinant vaccinia virus that contains the bacteriophage T7 RNA polymerase. The expression of 2C, or 2BC, contrary to 2B, was able to induce the proliferation of vacuoles morphologically similar to those found during poliovirus infection. These findings indicate that poliovirus protein 2C, in addition to its NTPase and RNA binding activities, is also endowed with the capacity to induce the formation of cytoplasmic vacuoles.