Heath - Virus response to pH changes

The Sindbis virus, or SINV, is the prototype for viruses spread by insects, which cause some of the most devastating and widespread diseases among humans. Exposure to low pH (acidic) conditions causes dramatic changes in the three-dimensional structure of SINV that can help the virus membrane fuse with a cell membrane when the pH returns to normal. Small-angle neutron scattering at Oak Ridge National Laboratory's High Flux Isotope Reactor is improving understanding of how SINV delivers its infectious RNA into host cells by revealing details of these structural changes. When the pH is reduced from 7.2 to 6.4, the RNA in the SINV core changes, and much of the protein associated with the interior liquid bi-layer moves to the exterior of the virus particle. The SANS data, the first to show how the RNA and lipid components interact with the virus proteins as the pH changes, improve understanding of the effects of pH on SINV, which is an excellent model for studies of virus structure and function. - Deborah Counce, 865.574.0644, February 21, 2012