3. aspergillum, which resembled the genus-characteristic
conidia-forming structure of these fungi. Aspergillus is an
extremely diverse and widely distributed genus of filamentous
ascomycete fungi. It includes over 200 species of mostly
asexual fungi found ubiquitously In soil as well as in forage
products, food, dust, organic debris, and decomposing
vegetation. Being supreme opportunists, the aspergilli have
adapted to various chemical, physical, and biological
stresses and have repeatedly changed their lifestyle and
reproductive mode in the course of evolution. While most of
them are thought to be saprophytes.
The Aspergillin number of species are able to infect wounded
plants and animals. The advent of immunosuppressive
agents and other medical advances created a new biological
niche for aspergilli, the immunocompromised human host.
4. A. nidulans – may be amphotericin B resistant
The genus Aspergillus – ~180 species,
38 have caused disease (able to grow at 37C)
Common in the environment
A. nigerA. terreus – resistant to AmBA. flavus -sometimes amphotericin B resistant
www.aspergillus.org.uk
A. fumigatus low frequency of azole resistance
Aspergillus
fumigatus
conidial head
5. Aspergillus fumigatus is a fungus of the genus Aspergillus, and
is one of the most common Aspergillus species to cause
disease in individuals with an immunodeficiency.
A. fumigatus, a saprotroph widespread in
nature, is typically found in soil and decaying
organic matter, where it plays an essential
role in carbon and nitrogen recycling.
A. fumigatus is a well-known pathogenic fungus
that is responsible for more than 80% of aspergillosis,
especially in immunocompromised patients.
A. fumigatus has 23 allergenic proteins.
hermotolerance – Ability to thrive at ≥ 37 C.
Ability to sense and utilize nutrients in different forms and from
difference sources.
6. Sputum Cultures for Fungus
Bacteriological media inferior to
fungal media – 32% higher
yield on fungal media
A four day A. fumigatus
culture on malt extract
agar (above). Light
microscopy pictures are
taken at 1000x, stained
with lacto-phenol cotton
blue.
7. Structure of A. fumigatus
. On the surface of the expanded apical region are a
series of spore-bearing cells called phialides. Repeated
mitotic division in the phialide nucleus yields a chain of
asexual spores usually called conidiospores or conidia.
The conidiospore varies in shape from spherical to
elongate and may be smooth or echinulate. Conidia are
extremely hydrophobic and are easily dispersed by air.
Modern taxonomic works also rely on characteristics of
the whole colony (color, size, presence or absence of
scle- rotia and pigments) when strains are grown under
standardized culture conditions (Klich 2002; Samson,
Hong et al. 2006). Figure 1.1 is an example of typical
Aspergillus conidia and a conidiophore.
10. Aspergillosis
Aspergillosis is a spectrum of diseases in humans and animals caused
by members of the genus Aspergillus.
Aspergillus is a fungus whose spores are present in the air we breathe,
but does not normally cause illness.
usually occurs in people with lung diseases or weakened immune
systems. The spectrum of illness includes allergic reactions, lung
infections, and infections in other organs.
(1) Mycotoxicosis due to ingestion of contaminated foods
(2) Allergy and sequelae to the presence of conidia or transient
growth of the organism in body orifices
(3) Colonization without extension in preformed cavities and
debilitated tissues
(4) Invasive, inflammatory, granulomatous, necrotizing disease of
lungs, and other organs
(5) Systemic and fatal disseminated disease.
11. CLASSIFICATION OF ASPERGILLOSIS
Persistence without
disease - colonisation
of the airways or
nose/sinuses
Airways/nasal
exposure to
airborne
Aspergillus
Invasive aspergillosis
• Acute (<1 month course)
• Subacute/chronic necrotising (1-3 months)
Chronic aspergillosis (>3 months)
• Chronic cavitary pulmonary
• Aspergilloma of lung
• Chronic fibrosing pulmonary
• Chronic invasive sinusitis
• Maxillary (sinus) aspergilloma
Allergic
• Allergic bronchopulmonary (ABPA)
• Extrinsic allergic (broncho)alveolitis (EAA)
• Asthma with fungal sensitisation
• Allergic Aspergillus sinusitis (eosinophilic
fungal rhinosinusitis)
14. Aspergillus Secondary
Metabolites
aflatoxin
as a cause of human liver cancers. Acute human afl
atoxin poisoning, however, is rare and usu- ally only
occurs when starvation forces people to subsist on
moldy foods.
Lovastatin
While Aspergillus infections and toxins detract from the
quality of human life, some of the products of
Aspergillus metabolism have made positive
contributions to the human health as drugs.
15. Aspergillus fumigatus is exceptional among microorganisms in being both a
primary and oppor- tunistic pathogen as well as a major allergen. Its conidia
production is prolifi c, and so human respiratory tract exposure is almost
constant. A. fumigatus is isolated from human habitats and vegetable c
ompost heaps. In immunocompromised individuals, the incidence of invasive
infection can be as high as 50% and the mortality rate is often about 50%.
The interaction of A. fumigatus and other a irborne fungi with the immune
system is increasingly linked to severe asthma and sinusitis (Nierman, Pain
et al. 2005). British physician John Hughes Bennett is credited with the fi rst
published description of an Aspergillus infection, an aspergilloma (“fungus
ball”) in 1842. Subsequently, it has been learned that most asper- gillomas
are caused by A. fumigatus, which is a thermotolerant species often resident
in compost heaps. (Brakhage and Langfelder 2002). It is one of the most
common airborne fungi, and humans and other animals regularly inhale
numerous conidia. In healthy organisms, the respiratory tract eliminates
these spores. For decades A. fumigatus was c onsidered a weak pathogen,
associated mostly with allergic condi- tions such as “farmer’s lung” and
bronchopulmonary aspergillosis (Latge 1999). The fi rst case of inva- sive
human aspergillosis, in an immunocompromised patient, was made in 1953.
16. Allergic bronchopulmonary aspergillosis usually is
found associated with asthma and cystic fi brosis.
Some patients experience little permanent loss of
respiratory function while others develop irreversible,
obstructive lung diseases.
Allergic bronchopulmonary aspergillosis usually is
found associated with asthma and cystic fi brosis.
Some patients experience little permanent loss of
respiratory function while others develop irreversible,
obstructive lung diseases.
17. he species is only known to reproduce by asexual means, but there has been
accumulating evidence for recombination and gene flow from population genetic
studies, genome analysis, the presence of mating-type genes and expression of
sex-related genes in the fungus.
Here we show that A. fumigatus possesses a fully functional sexual reproductive
cycle that leads to the production of cleistothecia and ascospores, and the
teleomorph Neosartorya fumigata is described. The species has a heterothallic
breeding system; isolates of complementary mating types are required for sex to
occur.
We demonstrate increased genotypic variation resulting from recombination
between mating type and DNA fingerprint markers in ascospore progeny from an
Irish environmental subpopulation. The ability of A. fumigatus to engage in sexual
reproduction is highly significant in understanding the biology and evolution of
the species.
The presence of a sexual cycle provides an invaluable tool for classical genetic
analyses and will facilitate research into the genetic basis of pathogenicity and
fungicide resistance in A. fumigatus, with the aim of improving methods for the
control of aspergillosis. These results also yield insights into the potential for
sexual reproduction in other supposedly ‘asexual’ fungi.
18.
19. The first known human exploitation of Aspergillus
for beneficial purposes was for the
transformation of rice, soybeans, and other plant
foods to improve their palatability and to make
them available for further fermentation by yeasts
and bacteria. The domestication of Aspergillus
for food production is thought to have originated
in China close to 2000 years ago. Subsequently,
similar food fermentations were adopted in
Indonesia, Japan, Korea, and other parts of Asia.
Koji is the Japanese name for mold- fermented
grains and/or soybeans.
Beneficial of A. fumigatus
The genus Aspergillus was named by P. A. Micheli in 1729 after a holy water sprinkler.
Hypothesis and ObjectivesObjective 1: Determine if the allergen potency (IgE binding capacity)of A. fumigatus spores is a function of temperature.HYPOTHESIS: Allergen potency is a function of the environment inwhich a spore is produced.Conclusions● Environmental conditions during sporulation influencethe allergenicity “IgE binding capacity” and allergenproduction in A. fumigatus spores.Human IgE binding Total and allergenic Protein Microarray and qPCR gene expression● Culturability and qPCR can underestimate (5 to 50 times) the allergenicity of A. fumigatus spores that wereproduced at lower temperature.