Publications by authors named "B Montgomery Pettitt"

202 Publications

A norovirus uses bile salts to escape antibody recognition while enhancing receptor binding.

J Virol 2021 Apr 7. Epub 2021 Apr 7.

University of Texas Medical Branch at Galveston, Department of Biochemistry and Molecular Biology, Galveston, Texas, USA.

Noroviruses, members of the family, are the major cause of epidemic gastroenteritis in humans, causing ∼20 million cases annually. These plus-strand RNA viruses have T=3 icosahedral protein capsids with 90 pronounced protruding (P) domain dimers to which antibodies and cellular receptors bind. In the case of mouse norovirus (MNV), bile salts have been shown to enhance receptor (CD300lf) binding to the P domain. We previously demonstrated that the P domains of several genotypes are markedly flexible and 'float' over the shell, but the role of this flexibility was unclear. Recently, we demonstrated that bile causes a 90° rotation and collapse of the P domain on to the shell surface. Since bile binds distal to the P/shell interface, it was not at all clear how it could cause such dramatic changes. Here we present the near-atomic resolution cryo-EM structure of the protruding MNV complexed with a neutralizing Fab. Combined with previous results, we show here that bile salts cause allosteric conformational changes in the P domain that block antibody recognition to the top of the P domain. In addition, bile also causes a major rearrangement of the P domain dimers that are likely responsible for the bile-induced collapse of the P domain onto the shell. In the contracted shell conformation, antibodies to the P1 and shell domains are not expected to bind. Therefore, at the site of infection in the gut, the host's own bile allows the virus to escape antibody-mediated neutralization while enhancing cell attachment.The major feature of the Calicivirus capsids are the 90 protruding domains (P domains) that are the site of cell receptor(s) attachment and antibody epitopes. We previously demonstrated that these P domains are highly mobile and that bile causes these 'floating' P domains in mouse norovirus (MNV) to contract onto the shell surface. Here, we present the near atomic cryo-EM structure of the isolated MNV P domain complexed with a neutralizing Fab fragment. Together, the data shows that bile causes two sets of changes. First, bile causes allosteric conformational changes in the epitopes at the top of the P domain that block antibody binding. Second, bile causes the P domain dimer subunits to rotate relative to each other, causing contraction of the P domain that buries epitopes at the base of the P and shell domains. Collectively, MNV uses the host's own metabolites to enhance cell receptor binding while simultaneously blocking antibody recognition.
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http://dx.doi.org/10.1128/JVI.00176-21DOI Listing
April 2021

An Online Plastic Surgery Nonclinical Elective: Virtual Surgical Education in the Era of Coronavirus Disease of 2019.

Plast Reconstr Surg 2021 04;147(4):726e-727e

Division of Plastic Surgery, Emory University School of Medicine, Atlanta, Ga.

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http://dx.doi.org/10.1097/PRS.0000000000007725DOI Listing
April 2021

Reply.

J Vasc Surg 2021 Mar;73(3):1112-1113

Department of Surgery, Emory University School of Medicine, Atlanta, Ga.

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http://dx.doi.org/10.1016/j.jvs.2020.10.034DOI Listing
March 2021

Implementation and evaluation of eight virtual surgical electives for medical students during the COVID-19 pandemic.

Am J Surg 2021 Feb 4. Epub 2021 Feb 4.

School of Medicine, Department of Surgery, Emory University, USA. Electronic address:

Background: Eight novel virtual surgery electives (VSEs) were developed and implemented in April-May 2020 for medical students forced to continue their education remotely due to COVID-19.

Methods: Each VSE was 1-2 weeks long, contained specialty-specific course objectives, and included a variety of teaching modalities. Students completed a post-course survey to assess changes in their interest and understanding of the specialty. Quantitative methods were employed to analyze the results.

Results: Eighty-three students participated in the electives and 67 (80.7%) completed the post-course survey. Forty-six (68.7%) respondents reported "increased" or "greatly increased" interest in the course specialty completed. Survey respondents' post-course understanding of each specialty increased by a statistically significant amount (p-value = <0.0001).

Conclusion: This initial effort demonstrated that VSEs can be an effective tool for increasing medical students' interest in and understanding of surgical specialties. They should be studied further with more rigorous methods in a larger population.
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http://dx.doi.org/10.1016/j.amjsurg.2021.01.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857999PMC
February 2021

A Strategy for Undergraduate Medical Education in Urology During the COVID-19 Pandemic.

J Surg Educ 2021 May-Jun;78(3):746-750. Epub 2020 Sep 14.

Department of Urology, Emory University School of Medicine, Atlanta, Georgia. Electronic address:

Objective: To provide a framework for a virtual curriculum during the COVID-19 pandemic for medical student educators that introduces and teaches clinical concepts important in urology and surgical specialties in general.

Methods: We created a 1-week virtual urology course utilizing interactive lectures, case-based exercises, and faculty-proctored surgical video reviews. Students were assigned self-study modules and participated in case-based discussions and presentations on a topic of their choice. Students' perceptions of urology as a specialty and the utility of the course was evaluated through pre- and postcourse surveys. Understanding of urologic content was evaluated with a multiple-choice exam.

Results: A total of nine students were enrolled in the course. All students reported increased understanding of the common urologic diagnoses and of urology as a specialty by an average of 2.5 points on a 10-point Likert scale (Cohen's measure of effect size: 3.2). Additionally, 56% of students reported increased interest, 22% reported no change and 22% reported a decreased interest in pursuing urology as a specialty following the course. Students self-reported increased knowledge of a variety of urologic topics on a 10-point Likert scale. The average exam score on the multiple-choice exam improved from 50% before the course to 89% after the course.

Conclusions: Various teaching techniques can be employed through a virtual platform to introduce medical students to the specialty of urology and increase clinical knowledge surrounding common urologic conditions. As the longevity of the COVID-19 pandemic becomes increasingly apparent and virtual teaching is normalized, these techniques can have far-reaching utility within the traditional medical student surgical curriculum.
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http://dx.doi.org/10.1016/j.jsurg.2020.09.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7490000PMC
September 2020