Differential gene expression response to acute and chronic Cytauzxoon felis infection in domestic cats (Felis catus)

•Feline genes upregulated in response to acute infection with C. felis were involved with response to inflammatory responses, and type I interferon signaling pathway among others.•Feline genes downregulated during acute C. felis infection were involved with biological processes in the cell cycle, cellular response to stress, and DNA metabolic process.•Feline genes upregulated during chronic C. felis infection were related to cell-cell adhesion, regulation of postsynaptic membrane potential among others.•Feline genes downregulated during chronic C. felis infection were involved with metabolic processes, homeostasis, and apoptotic signaling pathways and others. Cytauxzoonosis is a severe tick transmitted protozoan disease of domestic cats, caused by Cytauxzoon felis. The disease is characterized by acute onset of high fever, depression, lethargy, inappentence, anorexia, icterus, dehydration, hemolytic anemia, and alteration of immune response. The aim of our study was to further detail the immune response of domestic cats to C. felis infection by comparing the differential expression of feline immune transcriptional elements during acute and chronic cytauxzoonosis. True single molecule sequencing (tSMS) was used to analyze the whole genome of acutely and chronically infected C. felis cats, focusing on the analysis of genes involved on the immune response. Two C. felis donor cats were infested with Amblyomma americanum nymphs, which after repletion were collected and kept in humidity chambers until they molted. The resulting A. americanum were randomly selected to infest three C. felis naïve principal cats. Infection of these cats was confirmed by nested PCR of the 18S rRNA C. felis gene and clinical signs. RNA was extracted from whole blood at different time points and used for tSMS analyses, the results revealed overexpression in transcripts involved in type I interferon signaling, cellular and cytokine responses during the acute stage of infection, while cell cycle, and metabolic processes were downregulated. Genes involved in cell adhesion increased their expression in the chronic infected cats, whereas inflammatory and apoptotic related genes were downregulated. This study provided information on the host immune response to C. felis in domestic cats, demonstrating that inflammatory, apoptotic, and cell adhesion are some of the pathways altered during acute and chronic infection.