Engineering Immunogens to Focus the Immune Response on Broadly-Neutralizing Dengue Epitopes
Dengue virus causes hundreds of millions of human infections each year. There are four co-circulating dengue serotypes; primary infection by a single serotype results in febrile illness and subsequent lifelong immunity to that serotype, while secondary infections by heterotypic serotypes can lead to severe disease and even death. Severe dengue disease is likely caused by cross-reactive antibodies elicited during primary infection that can bind multiple serotypes but not neutralize them, instead facilitating viral entry into Fcγ receptor positive cells and thereby yielding “antibody-dependent enhancement“ (ADE) of infection. We propose to use structure-guided protein engineering to develop novel immunogens that focus the immune response so as to elicit broadly protective antibody responses avoiding ADE. In particular, we target two critical epitopes, the E glycoprotein domain III (DIII) and the E dimer interface (EDE), which are sites of binding by broadly neutralizing antibodies (bNAbs).
Target Validation Against Bacterial Pathogens
Many bacterial pathogens of humans have cbb3 oxidases terminal oxidases with high affinities for O2 that enable microbes to compete for O2 in the host, particularly in the microoxic settings associated with infections. In Pseudomonas aueroginosa (Pa), cbb3 oxidases are essential for fitness of the biofilm communities, and they are highly expressed by bacteria during chronic infections in cystic fibrosis. Because cbb3 oxidases, and the proteins that they interact with, are unique to bacteria and have several distinct features from those of mammalian oxidases, these enzymes are attractive drug targets for potential antibacterial therapies. Development of such drugs requires mechanistic understanding of these enzymes. We have identified two critical elements of the Pa cbb3-dependent respiratory pathway: the delivery of O2 under microoxic conditions by the O2 carrier hemerythrin (Hr) and the delivery of electrons for cbb3 catalysis by the electron carrier cytochrome c4 (cyt c4). The goals of this pilot project are to get key preliminary data on the mechanisms by which Hr and cyt c4 interact with cbb3 oxidases and to explore the possibility of targeting them in drug design.
Identification of the Biological Target and Mechanism of the Nuphar Alkaloids
PI: Jimmy Wu, PhD
6-hydroxythiobinupharidine, a member of the dimeric nuphar alkaloids, induces apoptosis in human leukemia cells faster than any known small molecule. Despite this, there exist only three published papers that attempt to elucidate how these molecules work. Yoshikawa et al. provides some evidence that the nuphars operate via the extrinsic pathway of apoptosis, while Gopas determined that the nuphars may inhibit NFkB. Unfortunately, both Yoshikawa and Gopas failed to carry out critical experiments to rule out alternative interpretations of their data. In contrast, our own preliminary investigations suggests that the nuphars operate via the intrinsic pathway of apoptosis and may, in fact, not inhibit NFkB. Our data, along with the unprecedented rate of cell death, may be indicative of a new biological target and/or mechanism of apoptosis. Therefore, there is a clear need to determine the target and mechanism of action of the nuphar alkaloids. Our long-term goal is to create and characterize novel compositions of matter that have the capacity to perturb previously undescribed protein targets and/or mechanisms of apoptosis.