Single-cell RNA-sequencing of peripheral blood mononuclear cells reveals the transcriptome profile of Microtus fortis immune cells during the early phase of infection with Schistosoma japonicum

Introduction The reed vole, Microtus fortis , is the only known natural non-permissive mammalian host of Schistosoma japonicum . However, the molecular mechanisms underlying this resistance have not been fully understood. Methods We performed single-cell RNA-seq to investigate the peripheral blood mononuclear cells (PBMCs) responses to S. japonicum in M. fortis and the susceptible host, Kunming mice. The samples were collected from uninfected animals (control group) and infected animals at 10 dpi. Results The major cell types identified in the PBMCs of the two species were monocytes, dendritic cells (DCs), T cells, NK cells, B cells, and erythrocytes. We observed that the population of monocytes decreased considerably in the bloodstream after infection in both M. fortis and Kunming mice. However, differential gene expression analysis revealed that Cxcl9 was upregulated in M. fortis monocytes after infection, while it was not detected as a DEG in Kunming mice. In addition, we observed that infection induced the upregulation of IL2 and IL4 in M. fortis CD4+ T cells, and the expansion of the Th2 cell population. Regarding B cells, we did not observe any significant alteration among M. fortis B cell subpopulations after infection compared to the control. However, DEG analysis revealed that Igha, Ighg1, and Ighg3 were upregulated in M. fortis antibody secreting cells (ASCs) but not in Kunming mice. Discussion Together, our results suggest that both the innate and adaptive immune responses were activated in the peripheral blood of M. fortis at 10 dpi, while their activation was not obvious in Kunming mice at the same moment.