PhD Dissertation Topic:
Elucidating the mechamism(s) of Mycoplasma pneumoniae Vaccine-induced Disease Exacerbation
Mycoplasma pneumoniae is a highly contagious human respiratory pathogen that causes the majority of cases of primary atypical pneumonia worldwide. Significant morbidity due to M. pneumoniae infection in school aged children and young adults, coupled with growing antibiotic resistance and mortality in certain elderly patients make M. pneumoniae a significant threat to public health, and a strong candidate for vaccine development. Unfortunately, previous attempts at developing vaccines against M. pneumoniae have ended in frustration as no candidates have been able to provide sufficient protection, and some have even exacerbated disease in some individuals. The aim of my PhD project is to elucidate the mechanisms by which M. pneumoniae vaccines result in enhanced disease in individuals that are subsequently exposed to virulent M. pneumoniae. The elucidation of these mechanisms will hopefully serve to guide future vaccine development and will be a critical first step in resurrecting researchers’ interest in M. pneumoniae vaccine design. The work I completed during this project identified the lipid moieties of M. pneumoniae lipoproteins as the maladaptive factors that result in disease exacerbation. This work was published in the Nature Partner Journal – Vaccines, and you can access it by clicking here. I am currently in the process of wrapping up the experiments that identify the immunological phenomena that result in M. pneumoniae Vaccine-induced Exacerbation.
Side Projects I am leading:
Mycoplasma gallisepticum Vaccine Development
Mycoplasma gallisepticum is majorly known as a significant respiratory pathogen of poultry, and more recently as the etiologic agent conjuctivitis in house finches. While mortality due to M. gallisepticum infections is relatively low in poultry, the pathogen does cause significant morbidity in affected flocks. M. gallisepticum is commonly involved in the polymicrobial “chronic respiratory disease” in broiler chickensl, leading to increased condemnations in the processing plant. Infection in layers and breeders is typically subclinical, but causes a significant reduction in the number of eggs laid. Altogether, these amount to a significant economic loss in the industry, making M. gallisepticum an attractive target for veterinary vaccine development. While there are a number of vaccines in the market, many are live-attenuated strains and can sometimes cause disease in in younger birds. One of these vaccines, the F-strain, is attenuated in chickens but is fully virulent in turkeys. Designing a safe and efficacious vaccine against M. gallisepticum is therefore of paramount importance. I am currently working on developing a sub-unit vaccine against this significant poultry pathogen.
Assessing the role of Mycoplasma pneumoniae infection in the exacerbation of asthma/allergic airway disease
In addition to accounting for roughly 20-50% of all cases of community acquired pneumonia, M. pneumoniae has also been implicated with the exacerbation of other respiratory conditions such as asthma. Studies utilizing a recombinant M. pneumoniae Community-acquired respiratory distress syndrome (CARDS) toxin have linked this novel ADP-ribosylating and vacuolating cytotoxin to the pulmonary eosinophilic inflammation that characterizes allergic airway disease in mice. It is unclear however, if the CARDS toxin is the only factor of M. pneumoniae infection that results in the exacerbation of allergic airway disease, as no studies have been conducted with a CARDS deficient strain of M. pneumoniae. As part of this project, I have mentored two outstanding undergraduate students. The first student, Janet Olivas, was a visiting scholar from the University of Texas at El Paso that spent a summer in our lab as part of the NIH funded BUILDing SCHOLARS program. During this visit, Janet learned about random transposon mutagenesis and developed a haystack PCR screen in order to identify a putative CARDS toxin mutant from a M. pneumoniae pool of 1856 mutants. She was able to identify a mutant with a transposon insertion in Domain 2 of the CARDS toxin and presented her findings at the 3rd Annual BUILDing SCHOLARS Symposium and Consortium Meeting and at the 2018 Annual Biomedical Research Conference for Minority Students (ABRCMS). The second student, Nikaash Pasnoori, was an UConn OUR funded honors undergraduate student that assessed the in vivo virulence of the CARDS mutant identified by Janet. I am currently working on finishing up the remainder of the experiments for this project.
Assessing the therapeutic potential of monoclonal antibody targeting the primary adhesin of M. pneumoniae
Cytadherence is a critical step in bacterial pathogenesis as it mediates colonization of the host. M. pneumoniae adheres to host cells through a complex “attachment organelle”. Multiple proteins are involved in the organization of this attachment organelle, although the primary protein responsible for adherence is the P1 adhesin. Our lab has previously developed monoclonal antibodies for the specific detection of the M. pneumoniae P1 adhesin, and we are currently assessing the thereapeutic potential of this antibody. As part of this project I have had the privilege of mentoring Morgan Hunte, an outstanding undergraduate student. Morgan is now a Laboratory Technician at Sanofi Protein Sciences.
Mycoplasma pneumoniae Vaccine Development
Inspired by the findings from my main PhD project, I am also working on the development of M. pneumoniae vaccine candidates. This work is unfortunately confidential at this point but you can read more about it in our provisional patent application that you can access by clicking here. As part of this work I also serve as a mentor to an IDEA grant funded undergraduate student, Meagan Goodridge that aims to identify M. pneumoniae protective antigens through various proteomic approaches.
Mycoplasma gallisepticum: Avian Influenza Co-infection
The subject of co-infection is increasingly recognized as a complex process that breaks down the one-pathogen/one-disease paradigm, altering pathologic and immunologic effects in the host, severity and duration of disease, and transmission of disease in ways that are different, and often greater, than would be expected from single infections. Co-infection of M. gallisepticum and LPAIV in poultry is found where both pathogens are circulating. Notably, LPAIV has been directly shown to exacerbate M. gallisepticum respiratory disease in chickens, and recent work from our lab has shown that M. gallisepticum co-infection can enhance influenza fitness and pathogenesis. We are currently investigating the mechanisms responsible for this synergistic effect.
Projects I have helped/am helping others with:
Assessing the in vivo role of a Vibrio parahemolyticus T3SS2 effector protein
Vibrio parahaemolyticus is a bacterium that lives in brackish saltwater and causes gastrointestinal illness in humans. V. parahaemolyticus naturally inhabits coastal waters in the United States and Canada and is present in higher concentrations during summer. When ingested, V. parahaemolyticus causes watery diarrhea often with abdominal cramping, nausea, vomiting, fever and chills. V. parahaemolyticus can also cause an infection of the skin when an open wound is exposed to warm seawater, and has been shown to experimentally cause pulmonary disease in mice. V. parahaemolyticus utilizes type III secretion systems to inject effectors that disrupt signal transduction in eukaryotic hosts during infection. Recent studies have shown that the V. parahaemolytics T3SS1 system plays a role in the induction of pulmonary disease in rodents, while T3SS2 systems seem to be required for colonization of the GI tract. As part of this project I will help assess the role of a V. parahaemolyticus T3SS2 effector protein in the colonization of the GI tract by providing assistance with animal models of infection.
I have also provided assistance with animal handling, vaccinations, infections, and necropsies for various projects such as assessing differential antibody responses to mice vaccinated with M. pneumoniae LAMPs or dLAMPs, assessing the in vivo efficacy of a micro-needle delivered Prevnar vaccine, assessing the thermostability of Prevnar, assessing the in vivo efficacy of a proprietary nanoparticle utilized as a therapeutic against House-Dust Mite induced allergic airway disease, and assessing differential pneumococcal vaccine efficacy in wild type mice and mice with sickle cell disease (SCD).