By itself, the WNV-Cp protein can cause inflammation. Weiner and his colleagues found that WNV-Cp drives apoptosis in cell cultures through what is called the mitochondrial pathway. The protein begins the process of cell suicide by somehow disrupting the membrane potential of the cell's mitochondria, which then leads to the activation of proteins such as caspase-9 and caspase-3 that start a cascade of reactions to subsequently cause the cell to digest itself.
Since the protein enters the nucleus of the cell, it is possible that WNV-Cp changes the host cell's transcriptional machinery, resulting in an over production of certain proteins related to an apoptotic program, which consequently feed back to the mitochondria.
Alternatively, as WNV-Cp moves from the cytoplasm to the nucleus, it may inactivate an important part of the cell's natural control system that keeps apoptosis in check overpowering the guard as it were thus inducing the cell suicide.
"Overall, our data suggest that WNV-Cp may interact with host cell proteins to induce apoptosis in the host cell," said Weiner, "Identifying these proteins will likely give more insight into the biology of West Nile."
The proteins pathogenic properties extend outside of the tissue culture. WNV-Cp also directly caused apoptosis and inflammation in mouse muscle cells. More importantly, the WNV-Cp protein caused inflammation and apoptosis in mouse brain in a manner similar to what is observed in natural infections.