Researchers from the George Mason University in Virginia have discovered that the vaccine which was used to wipe out smallpox also offers some protection against HIV. They theorise that HIV has flourished now that the smallpox vaccine is no longer used. The researchers also suggest that smallpox vaccination offers cross-protection through long-term alterations in the immune system. This may include the expression of a receptor called CCR5 on the surface of white blood cells, which is recognised by both smallpox and HIV.
The CCR5 gene encodes for a member of the beta chemokine receptor family, which is predicted to be a seven transmembrane protein similar to G protein-coupled receptors. This protein is expressed by T-cells and macrophages, and is known to be an important co-receptor for macrophage-tropic viruses, including HIV, that enables pathogens to enter host cells. Defective alleles of this gene have been associated with HIV infection resistance. Two splice variants have been found for this gene, and the functional and structural characteristics of each splice variant can be analysed with SynaTate™.
SynaTate is a sequence mining tool which can be used to find putative regions of ‘importance’ or SIGNIFICANCE in a given sequence. This application analyses patterns within sequences. It subsequently associates keywords and annotations to those patterns. Using SynaTate, we are able to see that the two transcripts are coded in different reading frames. Both show a region that has the keyword ‘transmembrane receptor’ highlighting a domain which is involved in pathogen entry into host cells. With this information, researchers could design entry inhibitor drugs that disrupt this region in order to prevent interaction between CCR5 and pathogens such as HIV.