MASS SPECTROMETRY IMAGING UNCOVERS CHEMOTYPIC HETEROGENEITY DURING VIRAL INFECTION OF A BLOOM-FORMING ALGA

Emiliania huxleyi is a unicellular alga that forms massive blooms in the ocean and has a great ecological importance. It is infected by a specific virus, E. huxleyi virus (EhV), thus serving as an important model system for host-pathogen interactions in the ocean. Viral infection induces the production of a myriad of chemicals derived from the rewired primary and specialized metabolism of infected cells. These are potentially secreted or released upon cell lysis and serve as chemical cues (infochemicals) in a signaling system that may modulate the susceptibility of neighboring cells and the population response. Nevertheless, the identity and functional role of these metabolites is thus far unknown.

We apply two complementary mass spectrometry imaging (MSI) techniques, matrix-assisted laser desorption/ionization (MALDI) and a “Flow-probe” in situ micro-extraction system, in order to study the metabolic fingerprints of different stages of viral infection and the nature of the infochemicals produced. Following metabolic changes in a spatial manner allows us to identify different sub-populations of cells that emerge during viral infection and are otherwise elusive when relying on bulk analysis at the population level. We further aim at studying the signaling roles of specific metabolites in modulating population heterogeneity and in regulating the population level response.

Deciphering and characterizing infochemicals that mediate the interactions between a host and its specific virus will contribute to our understanding of infection and defense strategies and the impact of viral infection on other components of the microbial food webs. These molecules can be further utilized as potential metabolic biomarkers to detect viral infection during natural E. huxleyi blooms.