Scientists Find Protein That Prevents H1N1 Infection
A team of scientists from several institutions have unexpectedly discovered a family of human proteins that help prevent infection by the H1N1, dengue, and West Nile viruses. The researchers found that the naturally occurring proteins, whose functions were previously unknown, can block the replication of these viruses.
The research effort, which was led by Stephen J. Elledge and his colleague, Abraham Brass, both of Howard Hughes Medical Institute, was a collaborative one and included scientists from Harvard Medical School, Massachusetts General Hospital, Yale Medical School, and the Wellcome Trust Sanger Institute in Cambridge, United Kingdom.
Viruses have few genes of their own, so they typically must seize proteins that are produced by its host (e.g., humans) to enter the host’s cells and reproduce inside them. The scientists in this study were looking for the proteins that the H1N1 virus needs to complete its life cycle and were using a high-speed screening method to process thousands of proteins. During this process, they unexpectedly found genes that could block replication of the virus.
The genes that they found code for three members of a family of proteins called Interferon-Inducible Transmembrane (IFITM): IFITM1, IFITM2, and IFITM3. These proteins are not new: they were first identified in 1984, but scientists had never understood their function. Dr. Elledge and his team found that the H1N1 virus replicated five to ten times better when one of the proteins, IFITM3, was not present. This led them to increase the production of IFITM3 in cells and when they did, the protein completely blocked replication of H1N1. They also found that the proteins also blocked replication of strains of West Nile virus and dengue virus.
Although all three of the proteins demonstrated the ability to block replication of the viruses, IFITM3 had the strongest and most consistent results when overproduced. For now, the researchers are not sure how IFITM3 and its other family members block viruses, but tests thus far indicate that the IFITMs cause molecules brought in through the cell membranes, such as viruses, to be deposited in an area where they are quickly made harmless.
The researchers believe their discovery of the IFITM proteins could lead to the development of more effective drugs against viruses such as H1N1, including preventive drugs that could slow the transmission of influenza. Dr. Elledge also noted that manipulating the protein levels could help in the production of vaccines.
Howard Hughes Medical Institute, news release Dec. 17, 2009