Sarah E. Hobdey, Ph.D.

[Accepting students at both IVREF and ISU for Summer 2024]

Summary: Research in our laboratory is centered on the development of novel therapies for the treatment of life-threating necrotizing soft tissue infections caused by Gram positive bacteria. Morbidity and mortality from infections caused by Lancefield groups A, C and G streptococcus, Staphylococcus aureus including methicillin-resistant species (MRSA), and multiple clostridial species remains exceedingly high despite modern antibiotic regimens and intensive care measures. Through the production of potent, well-characterized, extracellular toxins, each organism causes rapidly progressive necrotizing infections that destroy skin, subcutaneous tissue, fascia and muscle, often leading to multiple organ failure, toxic shock syndromes and death. Survivors often require surgery, including amputation, necessitating prolonged hospitalization and rehabilitation. The most important factor contributing to poor patient outcomes is a delay in treatment, which permits bacterial proliferation and toxin production to proceed unchecked. To improve survival and reduce morbidity, we are pursuing a passive immunization strategy that can be delivered to the patient immediately upon clinical presentation and will neutralize the damaging toxins as they are secreted by the suspected pathogen(s).

Minimum classes: None

Projects: Our research relies on the isolation of B-cells that produce toxin-specific antibodies, cloning of these antibody genes and generating recombinant forms of these antibodies in vitro. In order to achieve this we must to produce recombinant bacterial toxins as ‘bait’ to isolate the toxin-specific B-cells, Project 1. Once the toxin-specific B-cells have been isolated and cloned, we need reproduce the human monoclonal antibodies in vitro using a mammalian expression system and characterized their ability to neutralize the specific bacterial toxins, in vitro and in vivo, Project 2.

Project 1) Creation of recombinant bacterial toxins used for isolation of toxin-specific B-cells. Techniques may include: bacterial expression, molecular cloning, polymerase chain reaction, protein purification utilizing fast protein liquid chromatography (FPLC), in vitro biochemical protein characterizations, spectrometry, flow-cytometry, polyacrylamide gel electrophoresis (PAGE), western blot.

Project 2) Development and characterization of recombinant anti-toxin antibodies. Techniques may include: cell culture, restriction enzyme-free cloning, transfection, site-directed mutagenesis, protein purification utilizing FPLC, in vitro (toxin reutilization assays), ex vivo (murine cardiomyocyte dysfunction) or in vivo (murine models of necrotizing infection) characterization of recombinant antibodies.