Potential pathogenicity of sexual Aspergillus fumigatus spores in embryonated chicken eggs

Ref ID: 19434

Author:

S. Seyedmousavi,1 A. J. M. M. Rijs,2 A. Inacio,3 J. van den
Bersselaar-Ypelaar,4 H. van der Lee,2 J. W. Mouton,2
W. J. G. Melchers2 and P. E. Verweij2

Author address:

1Radboud University Medical Centre, the Netherlands;
2Department of Medical Microbiology, Radboud University
Nijmegen Medical Centre, the Netherlands; 3Central Animal
Laboratory, Radboud University Nijmegen Medical Centre, the
Netherlands and 4QM

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objectives Aspergillus fumigatus is an ubiquitous saprotrophic fungus
available in the atmosphere, which is known to reproduce through
both asexual and sexual means. The experimental sexual crossing
studies showed that the mutated antifungal resistance genes will be
subsequently transferred to its offspring.Gaining insights into poential
virulence of sexual crossing and its subsequent progeny may help to
further explore more in details the required approaches responible for
the antifungal reistance and the natural peristence of A.fumigatus. In
the present study, we therefore evaluated the virulence potential of
A.fumigatus ascospores comparing to the asexual spores in an embry-
onated chicken eggs, as an alternative infection model.
Methods Two A.fumigatus strains (V 108-20 and V 108-21) were
used for this study. The mating type of each strain was first deter-
mined and then crossed to eachother on the oatmeal agar plates.
The crosses were assessed weekly until cleistothecia were developed.
The ascospores then were harvested from surface of plates and
heated for one hour at 70°C, in order to prevent the germination of
asexual spores. The aliquots of the asexual and corresponding sexual
spores were then used to determine their potential of pathogenicity
in an embryonated chicken egg model. The fertilized chicken eggs
were incubated at 37°C and 50 to 60% humidity in a specialized
incubator. On day 10 of incubation, the eggs were infected through
injection of a 0.1 ml inoculum to chorioallantoic membrane (CAM)
using a sterile 1 ml syringe. The holes were sealed with paraffin and
vitality (survival) was monitored daily by candling for up to
7 days.Each experiment was performed in two separate replicates.
Results All embryos infected with 103 to 106 asexual spores died
within 3 to 7 days post challenge. However, the infection with heat-
killed asexual spores was resulted to 100% survival. Chicken
embryos infected with the heated ascospores suspensions, were killed in a dose dependent manner, in which all the embryos infected with
106 ascospores died within 7 days post infection, but Killing was
delayed at lower dose (103 ascospores) showing the mortality up to
50%. The morphological and histopathological examinations of CAM
in dead embryos were revealed fungal growth and destruction of
blood vessels.
Conclusion In the present study, the mortality of the chicken
embryos was dependent on the viability and the heat-killed asexual
A.fumigatus spores were inactivated for reproduction and virulence.
Notably, our results revealed a link between sexual reproduction and
virulence potential of A.fumigatus, indicating that adaptations to
pathogenicity may occures in both sexual and asexual reporoduction
means. This may suggests a real concern for the disease manage-
ment of A. fumigatus due to the genetic variation,since sexual cross-
ing might produce offspring with increased virulence or resistant to
antifungal agents. Further molecular investigations are warranted to
explore the putative virulence genes of ascospore and its posible roles
related to antifungal resistance or persitence of A.fumigatus in the environment.

Abstract Number: p285

Conference Year: 2013

Link to conference website: NULL

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