Salivary mycobiome diversity at different stages of human immunodeficiency virus infection.

Background: The oral cavity is a common site for fungal infections in people living with HIV/AIDS (PLWHA), yet reports on oral mycobiome alterations remain limited. This study aimed to analyze differences in mycobiome diversity and community composition in the saliva of PLWHA at different infection stages.

Methods: Non-stimulated whole saliva samples were collected from 63 HIV-infected/AIDS patients, who were divided into four groups based on the CDC staging criteria (stage 0, n = 10; stage 1, n = 13; stage 2, n = 24; stage 3, n = 16), as well as from 24 HIV-negative individuals. Internal Transcribed Spacer (ITS) sequencing was employed to analyze species diversity and community composition differences, and correlations at the genus level with CD4⁺ T cell counts and HIV blood viral load (BVL) were evaluated.

Results: At the operational taxonomic unit (OTU) level, the alpha diversity of the mycobiome community in the HIV-positive groups exhibited a gradual decline as the disease progressed, with the lowest Shannon index in HIV stage 3 (p < 0.05 vs. other groups). At the phylum level, all groups were predominantly composed of Ascomycota, followed by Basidiomycota. At the genus level, Candida was the predominant genus in all groups, with its abundance increasing to varying degrees in HIV stages 1, 2, and 3 compared to the HIV-negative control group (HIV_neg), showing significant differences in stage 1 (p = 0.006 vs. HIV_neg), stage 2 (p < 0.05 vs. HIV_neg), and stage 3 (p < 0.001 vs. HIV_neg). The most pronounced increase was observed in stage 3, while non-dominant species were relatively reduced. Correlation analysis showed that Debaryomyces and Talaromyces were positively associated with CD4⁺ T cell counts. These genera may play a role in immune regulation during HIV progression and warrant further functional analysis. Whereas Penicillium showed a significant negative correlation with BVL, indicating its abundance may decrease with higher viral loads.

Conclusion: The oral fungal microecology undergoes dynamic changes with HIV progression. In stage 3, there appears to be a noticeable increase in Candida, accompanied by a relative decrease in other normally present non-dominant fungal species, potentially resulting in opportunistic fungal infections.