researcher in labInfluenza’s ribonucleoproteins (RNPs) contain the virus’s genetic material, plus the special enzyme that the virus needs to make copies of itself, according to scientists at The Scripps Research Institute (TSRI).

Images obtained used cutting-edge molecular biology and electron-microscopy techniques allowed researchers to “see” one of influenza’s essential protein complexes in unprecedented detail. The images show flu virus proteins in the act of self-replication, highlighting the virus’s vulnerabilities, something sure to be of interest to drug developers.

At the core of any influenza virus lie eight RNPs, tiny molecular machines that are vital to the virus’s ability to survive and spread in its hosts. Each RNP contains a segment of the RNA-based viral genome, which is coated with protective viral nucleoproteins and has a structure resembling a twisted loop of chain. The free ends of the “chain” are held by a flu-virus polymerase enzyme, which is responsible for making new viral genomic RNA and making the RNA gene-transcripts that will become new viral proteins.

Aside from its importance in ordinary infections, the flu polymerase contains some of the key “species barriers” that keep, for example, avian flu viruses from infecting mammals. Mutations at key points on the enzyme have enabled the virus to infect new species in the past. Thus, researchers are eager to know the precise details of how the flu polymerase and the rest of the RNP interact.

“Structural studies in this area had stalled because of the technical obstacles involved, and so this is a welcome advance,” said Ian A. Wilson, Hansen Professor of Structural Biology at TSRI and senior author of the report with TSRI Professors of Cell Biology Bridget Carragher and Clint Potter. “The data from this study give us a much clearer picture of the flu virus replication machinery.”