Session TOC. There are 3 abstracts in this session.

Session: Infectious Diseases, time: 10:15 - 10:40 am

Identifying ways that viruses manipulate the cellular proteome 

Matthew Weitzman1, 2
1UPenn Perelman School of Medicine, Philadelphia, PA; 2Children's Hospital of Philadelphia, Phildelphia, PA

Viruses are obligate intracellular parasites that manipulate cellular environments to achieve efficient viral gene expression, DNA replication and packaging of viral genomes. Viral DNA genomes replicating in the nucleus of infected cells encounter a myriad of host factors that can facilitate or hinder viral replication. The battle between virus and host generates a genomic conflict as the host attempts to limit viral infection and protect its genome. Viral proteins expressed early during infection modulate cellular proteins interacting with viral genomes, recruiting factors to promote viral replication while limiting access to antiviral repressors. We have employed a number of proteomic approaches to study virus-host interactions and identify the cellular factors that are harnessed or inactivated as viruses hijack cellular machinery. We have identified viral tactics deployed to eliminate, evade or exploit intrinsic cellular defense. Many of these involve changes to post-translational modifications, such as harnessing the cellular ubiquitin machinery to degrade or modify function of host proteins.  Studying the dynamic interactions on viral and host genomes has revealed insights into viral replication, and has identified intrinsic cellular defenses against viral infection. Proteomic approaches provide a global view of viral and host proteomes during infection, helping to explain how viruses takeover cellular processes and also suggest targets for antiviral therapies.

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Session: Infectious Diseases, time: 10:40 - 10:55 am

Inhibition of HIV Maturation via Selective Unfolding and Crosslinking of Gag Polyprotein by a Mercaptobenzamide Acetylator

Lisa M. Jenkins1; Elliott L. Paine1; Lalit Deshmukh2; Herman Nikolayevskiy2; Gaelyn C. Lyons1; Michael T. Scerba2; Kara George Rosenker2; John M. Louis2; Elena Chertova3; Rob Gorelick3; David E. Ott3; G. Marius Clore2; Daniel H. Appella2
1National Cancer Institute, NIH, Bethesda, MD; 2NIDDK, NIH, Bethesda, MD; 3Frederick National Lab for Cancer Research, Frederick, MD

Although antiretroviral therapy has advanced, there remains a critical need for new therapeutics, especially those targeted at resistant strains of HIV. The Gag polyprotein, and in particular its constituent nucleocapsid protein, NC, represents a prime target for antiretroviral inhibition. NC is composed of two highly conserved zinc-binding domains and plays multiple roles throughout the virus replication cycle. We have developed a class of small molecule inhibitors of NC, based upon an S-acyl-2-mercaptobenzamide thioester (SAMT) scaffold, that covalently modify the zinc-binding domains of NCp7 in vitro  and in cells. These compounds display potent antiviral activity without evidence of cytotoxicity in cell models, ex vivo cervical explants, and in animal models. We investigated the mechanism of viral inactivation of the Gag polyprotein both in vitro and in virions released from cells. Mass spectrometry experiments identified multiple sites of covalent modification throughout the Gag polyprotein due to SAMT reaction. The earliest reaction occur within matrix and NC, with additional sites observed at later times. These covalent reactions inhibit maturation and prevent formation of infectious viral particles. Targeting multiple residues in HIV Gag and Gag-Pol greatly limits the potential of the emergence of virus escape mutations, making mercaptobenzamide antiviral compounds a strong starting point for developing a new therapeutic agent against HIV.

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Session: Infectious Diseases, time: 10:55 - 11:10 am

Blood protein biomarkers that diagnose and classify individuals with Lyme disease

Yong Zhou1; Shizhen Qin1; Mingjuan Sun1, 2; Li Tang1; Xiaowei Yan1; Taek-Kyun Kim1; Juan Caballero3; Gustavo Glusman1; Mary E. Brunkow1; Mark J. Soloski4; Alison W. Rebman4; Gilbert Omenn1, 5; Robert L. Moritz1; John N. Aucott4; Leroy Hood1
1Institute for Systems Biology, Seattle, WA; 2Second Military Medical University, Shanghai, China; 3Molecular and Developmental Complexity Lab, Langeb, Irapuato, Guanajuato, Mexico; 4Johns Hopkins University School of Medicine, Baltimore, MD; 5University of Michigan, Ann Arbor, MI

BACKGROUND: Lyme disease, a tick-borne illness caused by the spirochete Borrelia burgdorferi, is the most popular and widely spread infectious disease in USA, with an CDC estimated ~300K new cases annually. Current laboratory diagnosis of Lyme disease suffers with low sensitivity, ineffective for early detection of infection and no predictive value for the risk of post-treatment Lyme disease syndrome, in ~20-30% of patients. Here we adapted an alternative approach to target proteins that may signal an exposure to B. burgdorferi in humans by investigating blood proteins that are expressed predominantly in human organs affected by the infection, e.g., brain, heart, liver and skin, as well as acute phase and innate immune response proteins. The main aim of this study is to discover surrogate biomarkers that support early diagnosis of Lyme disease and/or that predict a patient’s risk of progression to PTLDS after the acute phase.

METHODS: In this study, depleted serum samples from a longitudinal cohort were investigated by selected reaction monitoring, which includes 40 Lyme disease patients and 20 matched controls, with samples collected from time of diagnosis to 4-6 years post antibiotic treatment.

RESULTS: We identified 16 proteins—mainly acute phase / innate immune system response proteins and proteins highly enriched in B. burgdorferi affected organs—that may serve as biomarkers for early diagnosis of Lyme disease. Five of these 16 proteins may possess predictive value to distinguish patients who later developed PTLDS from those who returned to health after treatment. 

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