Virulence of <i>Aspergillus flavus</i> and relatives using the <i>Galleria mellonella</i> model

<i>Aspergillus</i> section <i>Flavi</i> encompasses multiple species, with <i>A. flavus</i> being significant for human health because of its dual role as a major aflatoxin producer and opportunist. However, the mechanisms underlying its virulence remain incompletely understood. This study evaluates the pathogenic potential of <i>A. flavus</i> and its relatives using the <i>Galleria mellonella</i> infection model. Twenty-six <i>A. flavus</i> isolates (clinical and environmental) and 17 relatives/domesticated species were tested in <i>G. mellonella</i>, with larval survival monitored over 7 d. Histology, direct microscopy, and culture were used to validate the infection. Growth kinetics and spore sizes were measured to evaluate correlations with pathogenicity. All <i>A. flavus</i> isolates demonstrated high virulence, causing 90%, and 100% mortality of <i>G. mellonella</i> larvae within 3 and 7 d, respectively, with no significant differences between sources. Aflatoxin-producers exhibited higher virulence, resulting in 100% mortality of <i>Galleria</i> larvae within 5 d (<i>p</i> < 0.05). Related species exhibited lower virulence; larval mortalities ranging from 20% to 70% within 3 d, ranked as <i>A. flavus</i> > <i>A. pseudonomiae</i> > <i>A. parasiticus</i> > <i>A. nomiae</i> > <i>A. tamarii</i> > <i>A. pseudocaelatus</i>. Growth kinetics and spore size were correlated with virulence, as rapid growth and smaller spores were associated with increased pathogenicity. <i>Aspergillus flavus</i> exhibits higher virulence than its relatives, with growth rate, and spore size influencing pathogenicity. The <i>G. mellonella</i> model proves effective for comparative virulence studies. These findings highlight the potential health risks of <i>A. flavus</i>, including its domesticated relatives used in food fermentations, necessitating further investigations into their pathogenic potential.