Table 1.
Summary of hit compounds identified from the antiviral library screen demonstrating enhanced antifungal activity in combination with amphotericin B.
Fig 1.
Identification of antiviral compounds with amphotericin B potentiating activity against A. fumigatus.
Screening of the MedChemExpress (MCE) Antiviral Compound Library at a final concentration of 16 µM against A. fumigatus AF293 in the presence of a subinhibitory concentration of AmB (0.25 µg/mL). Fungal growth was assessed after 48 hours by measuring the optical density at 530 nm. Green dots indicate compounds that achieved ≥80% growth inhibition compared to the no-drug control. The chemical structures of the selected hit compounds, cobicistat (COB) and elvitegravir (ELV), are shown above the screening plot.
Table 2.
Interaction between amphotericin B (AmB) with cobicistat (COB) and elvitegravir (ELV) against Aspergillus isolates.
Fig 2.
Effect of antiretrovirals alone and in combination with amphotericin B on the growth kinetics of A. fumigatus AF293.
A. fumigatus AF293 conidia (5 × 10⁴ conidia/mL) were incubated in RPMI-MOPS medium and fungal growth was monitored over a 48-hour period by measuring optical density at 530 nm at regular time intervals. (A) Growth kinetics of untreated control versus monotherapies: AmB at 0.25, 0.5, and 2 µg/mL; COB and ELV at 4 µg/mL. Only AmB at 2 µg/mL resulted in substantial inhibition, while sub-inhibitory doses and antiretrovirals alone had minimal impact. (B) Comparison of COB combinations: AmB 0.25/COB 4, AmB 0.5/COB 2, and AmB 0.5/COB 4 µg/mL. All combinations showed enhanced inhibition versus monotherapies, with the 0.5/4 pairing sustaining growth suppression across 48 hours. (C) Comparison of ELV combinations: AmB 0.25/ELV 4, AmB 0.5/ELV 2, and AmB 0.5/ELV 4 µg/mL. As with COB, the highest dose pairing (0.5/4) achieved the most durable inhibition.
Fig 3.
Inhibition of A. fumigatus hyphal growth by antiretroviral–amphotericin B combinations.
(A) Brightfield microscopy images of A. fumigatus AF293 grown for 16 h in RPMI-1640 medium under the following conditions: untreated control, amphotericin B (AmB, 0.03 µg/mL), cobicistat (COB, 16 µg/mL), elvitegravir (ELV, 16 µg/mL), AmB/COB, and AmB/ELV. Images were acquired at 20 × magnification on a Nikon Eclipse Ti2 microscope, with a 100 µm scale bar shown. (B) Quantification of hyphal lengths under each condition was done using ImageJ software. For each variable, 15 hyphae were measured, and data are presented as mean. Statistical significance was assessed using one-way ANOVA followed by Dunnett’s post hoc test for multiple comparisons. Asterisks indicate significant differences relative to the untreated control, *** (P < 0.005) and **** (P < 0.0001).
Fig 4.
Inhibition of A. fumigatus AF293 biofilm formation by amphotericin B in combination with HIV antiretrovirals.
Biofilms were established by incubating A. fumigatus AF293 (1 × 10⁴ CFU/mL) in RPMI-1640 medium for 24 hours in the presence of cobicistat or elvitegravir (16 µg/mL), either alone or combined with a sub-inhibitory concentration of amphotericin B (0.015 µg/mL; 0.0075 × MIC). Biofilm biomass was quantified using crystal violet staining, followed by solubilization and absorbance measurement at 600 nm. Statistical analysis was performed using one-way ANOVA with Dunnett’s post hoc test. Significant reductions were observed for both AmB/COB and AmB/ELV combinations. Asterisks indicate significant differences relative to the untreated control **** (p < .0001).
Fig 5.
Disruption of pre-formed A. fumigatus biofilms by amphotericin B in combination with cobicistat or elvitegravir.
Mature biofilms of A. fumigatus AF293 were allowed to form over 24 hours prior to treatment with increasing concentrations of AmB/COB and AmB/ELV combinations. Following 24 hours of drug exposure, residual metabolic activity was quantified using the XTT reduction assay. Statistical analysis was performed using one-way ANOVA with Dunnett’s test. Significant reductions in metabolic activity were observed for AmB/COB and AmB/ELV. Asterisks indicate significant differences relative to the untreated control. * (p = 0.0458) and **** (p < 0.0001).