Integration of transcriptomics, proteomics, and metabolomics data for the detection of the human pathogenic Prototheca wickerhamii from a One Health perspective

Prototheca species are the only microalgae known to cause opportunistic infections in vertebrates and humans. Most cases of protothecosis in humans are caused by Prototheca wickerhamii, but knowledge of the pathogenicity and biology of Prototheca is limited. Globally, the diagnostic rate of Prototheca species infection is much lower than the actual rate of P. wickerhamii. The precise mechanisms underlying the pathogenesis of Prototheca infections remain unclear. In this study, we identified a strain of P. wickerhamii with atypical colony morphology. To reveal the morphological differences between P. wickerhamii S1 (mucous) and the molecular basis of its pathogenicity, the transcriptomics, proteomics, and metabolomics of two pathogenic P. wickerhamii strains and one environmental strain were analysed. Interestingly, mannan endo-1,4-beta-mannosidase was significantly downregulated in P. wickerhamii S1, which contributes to a thinner cell wall in S1 compared to strains with typical colony morphology, and the toxicity of macrophages is reduced. Metabolite analysis revealed that the mucoid appearance of P. wickerhamii S1 may have been caused by an increase in linoleic acid, glycerol, and other metabolites. There is still a need to better understand the ecology, aetiology, and pathogenesis of P. wickerhamii, and in particular, its transmission between humans, animals, and the environment, from a One Health perspective.

Automated summary

In this study, a mucous-like strain of P. wickerhamii with atypical colony morphology was identified. The transcriptomics, proteomics, and metabolomics of this strain and two other P. wickerhamii strains were analyzed to reveal the morphological differences and molecular basis of pathogenicity. Mannan endo-1,4-beta-mannosidase was found to be significantly downregulated in the mucous-like strain, resulting in a thinner cell wall and reduced toxicity to macrophages. Metabolite analysis suggested that the mucoid appearance may be caused by increased levels of linoleic acid, glycerol, and other metabolites. Further study is needed to understand the ecology, aetiology, and pathogenesis of P. wickerhamii, particularly its transmission between humans, animals, and the environment, from a One Health perspective.