Aspergillus fumigatus

Humans inhale hundreds of Aspergillus fumigatus conidia daily. Conidia germinate and produce hyphae or mycelia that eventually form a colony. The recognition of A. fumigatus pathogen-associated molecular patterns (PAMPs) by the pattern-recognition receptors (PRRs) of innate immune cells induces the phagocytosis and killing of the fungus and cytokine signaling that regulates the activation of adaptive immune responses and epithelial host defense. Severe asthma with fungal sensitization (SAFS), allergic bronchial pulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis (CPA), invasive pulmonary aspergillosis (IPA), and invasive bronchial aspergillosis (IBA) are some of the human diseases caused by Aspergillus species. A. fumigatus is able to evade the host’s innate immune system through the production of conidial hydrophobin (that can mask PAMPs on the cell wall) and melanin (which blocks the acidification of the phagosome and inhibits the NADPH oxidase complex responsible for the production of antifungal reactive oxygen species).