REPORT FOR THE PFIZER FOUNDATION  

  • Name: Edgar Musie
  • Dates of training fellowship at UVa : April 2006- ?April 2008
  • Home Institution: University of Venda, Thohoyandou, Limpopo Province, South Africa
  • Position there before coming to UVa: Lecturer in the Department of Microbiology, University of Venda

Summary of training at UVa

Mr. Musie is conducting his research project under the mentorship of Dr W. Michael Scheld. Dr. Scheld's lab research interests include molecular mechanisms of bacterial pathogenesis, sepsis and septic shock, adenosine receptors, inflammation, innate immunity, anthrax, antimicrobial resistance, appropriate use of antimicrobial agents, HIV/AIDS and vaccines. Mr. Musie is studying how immunomodulation of inflammation affects the progression of pneumococcal infection.

Meetings, conferences, workshops, courses attended

  • Microbes and Mucosal Immunity, June 28th -July 1st, 2006, University of Virginia, Charlottesville, Virginia
  • IDSA 44th Annual Meeting, October 12-15, 2006, Toronto, Canada.
  • MARCE meeting, October 17 - 18, 2006, University of Virginia, Charlottesville, Virginia

Presentations

  • Musie EM, Mhlongo AT,Hoosen AA, de Villiers BT, Obi CL. Characterization of Streptococcus pneumoniae isolates prevalent at Ga-Rankuwa Hospital, South Africa. ASTMH 55th Annual meeting, November 12-16, Atlanta, Georgia

 

Mentoring

Working in UVa's labs has afforded me the opportunity to collaborate with international scientists from many different countries, including Brazil, the Philippines, Japan and the United States. It has also given me the chance to learn more advanced scientific research techniques and share ideas to improve the health of the global community. Above all, I've benefited from the mentorship of Dr. Scheld and Dr. Richard Guerrant, two highly rated and internationally recognized scientists who are having a huge impact on global health. I will take the knowledge I acquire from this training back home to South Africa where I will share it with the students at the University of Venda.

Research activities

S. pneumoniae, one of the most important human pathogens  is today an even more serious menace because of its increasing resistance to penicillin, often a first-choice antibiotic. Despite the constant advances in the treatment of infectious diseases, the mortality rate associated with respiratory tract infections (pneumococcal pneumonia) has increased during the last two decades. Bacteremia and sepsis are the major causes of death. Studies into pathogenesis and pathophysiology of the bacterial infections have provided strong evidence that damage results from activation of the host inflammatory cascade rather than damaging effects of the pathogen itself. Thus modulation of the host response by adjuvant anti-inflammatory therapy might ameliorate bacterial infections outcome.

During inflammation, cells release inflammatory mediators that give rise to the symptoms of inflammation. The aim of my project is to determine how immunomodulation of inflammation affects the progression of pneumococcal infections in a sepsis animal model.

To achieve these objectives,

  • Optimization of culture conditions tending to prevent acidification and autolysis to obtain the appropriate viable log-phased cells to inoculate animals was established. The virulence of pneumococci varies between different mouse strains. Different mouse strains and different infection routes were tested to obtain reproducible animal models of pneumococcal infection (bacteremia/sepsis).
  • Preliminary experiments indicate S. pneumoniae seroyype 6B is less virulent and clearance of bacteria was evident in infection. No mouse died after 48 hours after intravenous/intranasal challenge. S. pneumoniae serotype 2 caused lethal systemic diseases after intranasal/intravenous challenge. Mice were unable to clear infection and died of septicemia. Balb/c mice were more susceptible to serotype 6B but more resistant to serotype 2 than C57bl/6. A sepsis animal model was established (C57bl/6 challenged with 1E6 CFU S. pneumoniae type 2)
  • Mice were treated with antibiotics at different times after challenged with bacteria to determine survival benefits of antibiotics at different times. The aim of the experiment was to study the effects of anti-inflammatory agents as adjuvant on the survival of mice challenged with bacteria.
  • Suppression of excessive proinflammatory mediator production is a characteristic of tolerance, an adaptive innate immune response to LPS. To investigate the affect of TLR4 agonist reLPS, on stimulating the immune response before acute S. pneumoniae infection in animal models, and determine the importance of TLR4 in modulating the response to S. pneumoniae. C57BL/6, C3HeJ and Balb/c mice were intravenously inoculated with a lethal dose of S. pneumoniae 48hrs after treatment with a nonlethal dose 10ug reLPS (dose every 12 hours). Pretreatment with reLPS induced a protective immune response through TLR4 (100% survival in C57BL/6, 50% Survival in Balb/c, as demonstrated by no survival benefits (0% Survival) in TLR4 complex -deficient C3HeJ mice. Our study suggests that stimulating this receptor before infection significantly enhances the immune response of immunocompetent mice to clear infection.

Future Plans

Investigate the microbial and inflammatory events that characterize survival or death after intravenous inoculation of mice with a lethal dose of S. pneumoniae, antibiotics, and adjuvant

  • Determine the presence of bacteria from blood, inflammatory cells/mediators from the serum.
  • Introduce therapeutic amounts of anti-inflammatories (ATL 313, Eternacept, PDTC, Perfinodone) and test for survival benefits in a lethal model +/- antibiotics.

If  survival enhancement is observed, Take time course cytokine profile to ascertain pathways from the knowledge of cytokines

  • Construct a pneumolysin vaccine - immunize against pneumolysin using filtered supernatant of 24h bacterial culture.