in mammals produce significantly less P78 proteins. The P78 protein is much more efficiently produced in RVFV in mosquito cells as it is required for viral spread in mosquitos. Overall, the cell line is heavily dependent on HS in RVFV entry. A computational study provided evidence that phlebovirus Gc proteins might be class II membrane fusion proteins. Final proof for this theory was given by the elucidation of the ectodomain's structure of RVFV Gc in its pre-fusion status. Gc has three domains with characteristics that resembled other class II proteins. An internal fusion loop was discovered, which is a critical aspect of all class II proteins. The location of a histidine in Gc resembled a pH sensing feature, which matches class II characteristics. Although there were many similarities within the structure of the RVFV Gc and class II proteins, the interface between domains I and II in RVFV Gc is more rigid and bigger than other class II proteins. Additionally, RVFV Gc has more disulfide bridges centralized in different locations than the other compared proteins. However, its overall structure and functionality is most closely resembling a class II membrane fusion protein compared to any other class. The pH sensing feature in the Gc protein is of note. The membrane fusion activity of the phlebovirus Gc proteins is very dependent on pH, as a low pH triggers the transport of virions into endolysosomes. Elevating intravesicular pH inhibits phlebovirus entry. However, it is still unclear whether Gc proteins must bind to a receptor before being triggered by pH or not. After the viral and endosomal membranes have been fused together, the L,M, and S genomic segments (associated with viral polymerase) are released into the cytoplasm. This initiates the transcription to genomic RNA into mRNA. Viral proteins begin undergoing translation before the transcription of mRNA has finished. The Gn and Gc phlebovirus proteins are encoded on the M-segment and undergo synthesis. The precursor Gn/Gc protein cannot be detected in a cell already infected with phlebovirus. It only is visible after the expression of the M-segment. If microsomal membranes are present, the precursor is cleaved, indicating cleaving by a host factor during the synthesis of the viral protein. The signal peptidase complex in the ER membrane is responsible for the cleaving of the precursor. This precursor is then translocated into the ER lumen, in which two hydrophobic domains are inserted with a third, cleaved