Mutations in the nuclear export protein and a certain enzyme of avian influenza virus H5N1 are required for replication in human cells in culture reports a study in Nature Communications this week. These findings further enhance our understanding of how the avian various can replicate in human cells.
Mutations in the polymerase and nuclear export genes of H5N1 are found in isolates from humans but whether these mutations contribute to the ability of the virus to replicate in human cells is unknown. Martin Schwemmle and colleagues used the sequence of a human isolate of H5N1 and removed mutations that seemed to have arisen due to adaptation in the human host. They found that this virus could replicate in avian cells but not in human cells in culture. When they added the mutation found in the polymerase gene back into the virus this partially compensated for the lack of replication of viral RNA in human cells. However the team reports that adding in the mutation in the nuclear export protein as well further enhanced the replication of the viral RNA in human cells in culture. The authors conclude that the mutation in the nuclear export protein enhances the activity of the avian polymerase in human cells in culture.
These findings contribute to our understanding of how avian virus adapts to be able to replicate in mammalian cells in culture.