Screening and Identification of mRNA Candidate Immunobiomarkers during Pregnancy in Sheep

Background: During pregnancy, the immune status of maternal animals undergoes significant changes. Effective monitoring of immunological biomarkers can provide valuable references for enhancing gestational management in livestock. This study aims to screen and identify mRNA-based candidate immunological biomarkers during ovine pregnancy, thereby establishing a scientific foundation for novel monitoring technologies to assess immune status in gestating animals. Methods: High-throughput sequencing technology was used to perform sheep ovaries transcriptome sequencing in four stages: follicular phase, luteal phase (10 days after estrus), 30 days of pregnancy, and 45 days of pregnancy. Differential mRNAs were obtained by bioinformatics analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed on the differential mRNAs. Result: The experiment successfully constructed mRNA libraries for pregnant and non-pregnant sheep, with an average output of 11.50 G data per sample. The average alignment rate of each sample to the genome was 93.88%, and the average alignment rate to the gene set was 49.46%. A total of 23,219 genes were detected, of which 467 were differential genes. Data analysis, GO, and KEGG pathway studies showed that MX2, DDX58, IRF7, IFIT5, ISG15, RSAD2, and PLA2G1B were significantly upregulated in ovarian tissues during pregnancy, all of which are involved in processes such as bacterial and viral defense, immune regulation et al. QRT-PCR was used to detect the expression of seven different mRNAs in the blood of pregnant ewes, and the result confirmed that the expression was significantly elevated in the blood of pregnant ewes (p less than 0.01). The experiment indicates that the seven mRNAs are promising candidate biomarkers for immune monitoring, which is of great significance for the screening and early intervention of diseases during animal pregnancy.