The Stobart Lab studies the role of environmental conditions on RNA virus infectivity and replication. Our ongoing studies with RSV, MHV, and other RNA viruses will provide new insights into mechanisms of virus stabilization and infectivity.
Stobart Research Lab
Butler University Department of Biological Sciences
Respiratory syncytial virus (RSV) is a human upper and lower respiratory pathogen and a leading cause of early infant hospitalizations and mortality worldwide. Yet, there remains no vaccine available for RSV.
Mouse hepatitis virus (MHV) is a murine virus associated high mortality in mice and is a common model of a study for coronavirus (CoV) biology. Human coronaviruses include SARS-CoV and MERS-CoV and several CoV are associated with the common cold.
ABOUT THE LAB
RSV
MHV Coronavirus
Significance and Systems
Overview
Dr. Stobart's research at Butler focuses on understanding the specific viral determinants of stability and replication of RNA viruses. Infants are hosts to a wide range of infectious agents due to their immature immune systems and lack of pre-existing immunity to circulating pathogens. Identifying environmental conditions or viral molecular determinants, which impair or alter viral stability or replication, may inform design of new vaccines, therapeutics, and contamination containment practices in common areas occupied by young children. Dr. Stobart's lab utilizes two different RNA virus systems : respiratory syncytial virus (RSV) and mouse hepatitis virus (MHV).
RSV
RSV is a negative-strand RNA virus (-ssRNA). Work on RSV in the Stobart lab is focused on evaluating the stability of circulating RSV strains and identifying specific molecular determinants which govern strain-specific differences. The identification of specific amino acids which confer increased stability may inform design of better stabilized vaccine preparations and/or highlight specific sensitive molecular targets for RSV therapeutics.
MHV Coronavirus
MHV is a positive-strand RNA virus (+ssRNA) and is a common model for study of coronavirus biology. Work on MHV in the Stobart lab focuses on understanding the relationship of structure and function of the main protease, nsp5 (or 3CLpro). Upon translation of the first viral open reading frame, nsp5 is responsible for catalyzing up to 11 proteolytic cleavage events. We aim to identify new critical residues and regions of nsp5 which may be targeted for inhibitor design.
Our lab is comprised entirely of a team of amazing Butler undergraduate students that volunteer their time to gain experience with and understanding of the scientific method through work with viral pathogens.
There are currently 8 undergraduates conducting research in the Stobart lab exploring 3 main research project areas.
Quick Stats on the Lab
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11 students have been published as authors on at least one scientific paper (2 students have multiple publications)
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10 students have presented our work at national meetings in Maryland, Minnesota, Wisconsin, and Oklahoma
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Students have been selected for summer research positions at Harvard University, University of Pittsburgh, and Emory University
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Post-graduation, lab members have been accepted into graduate (Ph.D.), medical (M.D. and D.O.), dental, optometry, and physician assistant (PA) programs
Current Research Projects
Understanding the Structure and Function of Coronavirus Protease nsp5
Coronaviruses are a significant cause of the common cold and have the potential to cause severe disease as evidenced by the recent emergence of SARS-CoV, MERS-CoV, and pandemic SARS-CoV-2 (COVID-19). The coronavirus protease nsp5 is essential for virus replication and is comprised of 3 distinct functional domains. Two of these domains are linked by a long interdomain loop of unclear function. Using site-directed mutagenesis and assays for replication and temperature-sensitivity, we are currently evaluating the role of several different structural and functional regions of the protease, including the inter-domain loop. These studies may define a new regulatory region of the nsp5 protease and provide a novel critical target for current inhibitor design efforts.
The Role of Environmental Factors on RSV Stability
Antimicrobial peptides (AMPs) are small chains of amino acids which are secreted by cells to provide innate immune defense against the establishment or proliferation of potentially pathogenic microbes such as bacteria and viruses. In the respiratory mucosa, a wide range of AMPs have been identified. However, the efficacy of these AMPs towards many human viral pathogens remains unclear. Studies evaluating susceptibility of RSV to AMP activity have been limited a single laboratory strain. Using a panel of recombinant RSV strains that differ in their expression of clinical surface proteins, F and G, we are investigating how differences in antigenic surface expression affect the activity of known antiviral AMPs. This work will provide new insight into the mechanisms of AMP inactivation of RSV and may provide renewed guidance on treatments for specific strains of the virus.
RSV Differences in Susceptibility to Antimicrobial Peptide Activity
Upon release from an infected cell, RSV virions must "survive" variations in temperature and pH both inside the respiratory mucosa and outside of the body in order to successfully transmit between individuals. Several papers have been published which demonstrate strain-specific differences with regards to the stability of RSV in differing temperatures. Recently, specific amino acids were identified in the viral fusion (F) which appear to play a partially conserved role in regulating RSV thermal stability. In addition, changes in pH are known to play a key role in both the stability and replication of a wide range of human viruses. The pH of human mucus and saliva can vary considerably. However, very little remains known regarding how pH differences affect RSV stability and biology. Using a panel of recombinant RSV strains that differ in their expression of clinical surface proteins, F and G, we are investigating how variations in temperature and pH affect RSV stability and biology. These studies will provide new insight into how environmental factors inactivate RSV and more specifically, the molecular mechanisms by which RSV maintains stability. Furthermore, identified differences in stability are being used to identify putative regulatory determinants through site-directed mutagenesis that may used to inform design of better stabilized or de-stabilized vaccine preparations.
Christopher C. Stobart, Ph.D.
Gallahue Hall Room 043
Department of Biological Sciences
Butler University
4600 Sunset Avenue
Indianapolis, IN 46208
Contact Dr. Stobart
Interested in finding out more and how you might get involved with our research, feel free to send an email using the link below or contact me with the information provided.
