The primary focus of the Lingappa lab is on understanding viral host interactions involved in assembly of human immunodeficiency virus (HIV). Their group previously identified a pathway for HIV capsid assembly that utilizes a cellular protein. Currently, they are studying the subcellular localization of these assembly intermediates, defining other cellular proteins present in these assembly intermediates, and determining how cellular proteins act during the membrane targeting step of HIV assembly. The Lingappa group also studies viral-host interactions important for the assembly of hepatitis C virus (HCV). They established a cell-free system that reconstitutes assembly of HCV capsids. This system has now been successfully used as a screen to identify anti-viral compounds that inhibit production of all flaviviruses, alphaviruses, and HCV. A third focus of the lab is on understanding regulation of the antiviral cellular protein Apobec 3G. This protein, which is present endogenously in human T cells, can function as a cytidine deaminase and hypermutate HIV DNA thereby blocking HIV infection. Using a high throughput assay developed by their lab for determining A3G deaminase activity, they demonstrated that enzymatic activity of endogenous A3G in human T cells is inhibited by a novel mechanism that they are now investigating.