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Investigators from the Consejo Superior de Investigaciones Científicas (CSIC) have recreated in the laboratory that uses the molecular machinery of the influenza virus to replicate and express its genetic material, one of the key aspects of their life cycle and, Consequently, the success of their infection. The work provides a new tool for scientists to conduct structural studies and to better understand the processes of gene expression and replication of the virus.

The research, published in PLoS Pathogens, has been led by researchers at the CSIC Juan Ortín and Jaime Martín-Benito, National Center for Biotechnology (CSIC) in Madrid. The authors have used biochemical techniques to create this reproduction, which can observe the machinery of virus replication with electron microscopy and, in turn, deepen the understanding of the virus. So far, the replication machinery could not be observed by electron microscopy because of its flexibility.

The model developed in the laboratory, says Martin-Benito, can be used for the analysis of all types and variants of influenza virus, including the new flu virus H1N1 or bird flu virus H5N1.

Why is it so complicated analysis of the flu virus? This pathogen has a spherical or slightly elongated, with a diameter of about 100 millionths of a millimeter. Its genetic material is composed of eight segments of RNA, housed in the heart of the virus nucleocapsid. To replicate, each of these fragments is associated with four different proteins, which results in a complex called ribonucleoproteína (RNP, in its English acronym), generating a closed structures that resemble the shape of a collar and have great flexibility. It is this flexibility which has so far prevented detailed structural studies.

This complex structure, as confirmed by research, molecular machinery functions as an automated, capable of doubling itself when it is inside the cell is infected by the virus. Its function is other than to produce a new generation of viruses that leave the cell ready to spread to other hosts.

The way that replicates the virus differs from other models, such as that used by the herpes virus, which usurp the replication machinery of the cell to infect it in order to multiply. "The way replication, however, does not condition the ability of infection or the virulence of the virus," says researcher CSIC.

In this study, teams of Ortín and Martín-Benito better understand the processes by which genetic information is copied from the virus and its proteins are expressed. "To know in depth the two processes can contribute to the development of potential inhibitors or activators of proteins that are part possibly treatment," explains the researcher.

To this end, the team has developed in a laboratory molecular machine with the same biochemical properties as the original virus. Its development has been complex: the authors took a virus RNP and biochemical techniques, and was cut again linked the RNA to form a mini-RNP in the laboratory. This mini-RNP has exactly the same biological activity of the virus RNP but is a more rigid structure and therefore could be used in structural studies. Determining the final structure has required the taking of thousands of images with a transmission electron microscope and their subsequent computer processing.