Single-Cell transcriptional landscape of lung cells from PCV2d-infected mice

Porcine Circovirus (PCV2) infection is prevalent in pig farming and causes significant economic losses. In recent years, the PCV2d subtype has become the main prevalent genotype in China. Compared with other subtypes, it exhibits stronger virulence, leading to more severe viremia and organ damage. Therefore, studying the biological characteristics of the PCV2d subtype holds great significance. We established a PCV2d infection model using BALB/c mice and employed single-cell RNA sequencing (scRNA-seq) to systematically analyze the transcriptome of 10 cell types in the lung tissue of infected mice. Notably, we developed a valuable marker gene catalog for these cell types. Compared to uninfected mice, PCV2d infection induced extensive viral replication and immunosuppressive responses in most cell types. More importantly, we suggest that monocyte macrophages with high levels of viral replication, proinflammatory cytokines, and various cell population interactions occurring through CD40_CD40L and CXCL14_CXCR4, as well as predominantly mediating antigen presentation and processing pathways in vivo to participate in the immune response, may contribute to PCV2driven inflammatory lung injury. Our data uncovered a complex yet unique immune response scenario in the lung tissue of mice post PCV2d infection and deciphered the potential mechanisms underlying PCV2d-driven inflammatory responses in mice. Furthermore, this study provides a rich database for the molecular basis of different cell types' responses to PCV2d infection.? Overall design: We divided 6-week-old mice into two groups of three mice each, male and female randomized to PCV2d attack and mock control. After the thirtieth day, mouse lung tissues were taken and mixed and prepared to send samples for sequencing.