Abstract Detail

Poster Session

Ratekin, Angela [1], Taylor, Bernadette [1], Volk, Thomas [2].

SURVIVOR: Human pathogen edition. The virulence factor BAD1 expressed by Blastomyces dermatitidis yeast as a potential modulator of the host immune response by altering the production of neutrophil extracellular traps.

Blastomycosis, a fungal infection of humans and other mammals, presents with a variety of disease states. The causative agent, Blastomyces dermatitidis, a thermally dimorphic fungal pathogen, is capable of infecting host mammals with intact immune systems. The mechanisms by which B. dermatitidis invades the human host and evades the immune response are not clearly understood. Blastomyces ADhesin factor (BAD1) is an essential virulence factor associated with the yeast form (but not the mycelial form) of B. dermatitidis. Neutrophils are the predominant cell population found in an initial immune response. The broad based budding yeast form of B. dermatitidis is large (up to 20µm diameter) making it difficult for the neutrophils and other phagocytic cells of the immune system to successfully phagocytize and eliminate the threat. However, neutrophils have an extracellular mechanism termed as Neutrophil Extracellular Trap (NET) consisting of a DNA backbone embedded with antimicrobial peptides and enzymes that inhibit or contain some pathogens. BAD1 attaches to phagocytic immune response cells resulting in immunomodulation, a change in chemical messaging. This change may result in decreased activation of neutrophils, resulting in decreased NET production. Decreased NET production may allow the yeast form of B. dermatitidis to further establish infection, evade the immune response, and possibly allow the yeast to enter the circulatory system of the host resulting in a systemic presentation of blastomycosis. Here, the production of NETs by human neutrophils in response to B. dermatitidis was observed by fluorescence microscopy and quantified by measuring relaxed chromatin, a component of NETs. A Colony Forming Unit (CFU) assay was used to determine the survival of B. dermatitidis post co-culture with neutrophils capable of NET production. Our hypothesis is that the expression of BAD1 from the yeast form of B. dermatitidis modulates the immune response resulting in reduced activation of neutrophils in the form of NETs. The reduced NET formation may allow yeast expressing BAD1 to evade (survive) host’s immune response.  

1 - Unversity of Wisconsin - La Crosse, Microbiology, 1725 State St, La Crosse, WI, 54601, USA
2 - Unversity of Wisconsin - La Crosse, Biology, 1725 State St, La Crosse, WI, 54601, USA

Keywords:
Medical Mycology
Immunology
Human Pathogen
thermal dimorph
Blastomyces dermatitidis
neutrophil.

Presentation Type: Offered Paper - Poster
Session: P1
Location: Lincoln Room/Kellogg Hotel and Conference Center
Date: Monday, June 9th, 2014
Time: 8:00 PM
Number: P1004
Abstract ID:118
Candidate for Awards:Graduate Student Poster Presentation Award