Abundance of transcript for receptors of type I interferon in blood leucocytes during early pregnancy in Nelore heifers

• Grant number: 18/25393-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): April 01, 2019
• Effective date (End): July 24, 2020
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Guilherme Pugliesi
• Grantee: Leonardo Marin Ferreira Pinto
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 15/10606-9 - Innovations in the early pregnancy diagnosis in cattle, AP.JP
• Associated scholarship(s): 19/21650-0 - Induction of puberty and fertility of Brahman-influenced heifers exposed to progesterone prior to artificial insemination, BE.EP.IC

Abstract

Brazil has the largest commercial cattle herd in the world, but it has low production indexes, as a result of low technification in the nutritional, sanitary, genetic and mainly reproductive management of the animals. Thus, strategies were adopted, such as the use of hormonal protocols in Fixed Time Artificial Insemination (FTAI) programs, making early gestational diagnosis necessary in order to reduce the interval of inseminations and thus the interval of births, optimizing farm productivity and increasing the profitability of the livestock sector. Several forms of gestational diagnosis are used and have been developed, but they only present good accuracy after the 21st gestational day, and an early diagnosis of the presence of the conceptus is interesting so that the interval of inseminations can be shortened. An alternative that has been studied is the quantification of type I interferon-stimulated transcripts in peripheral blood leukocytes at the beginning of gestation. The stimulation of these transcripts in their receptors in this cell group, however, is little explored in the literature. The aim of this study was to quantify transcription of type I interferon receptors (IFNAR1 and IFNAR2), responsible for the transcription of interferon type I-stimulated genes, in peripheral blood polymorphonuclear cells (PMN - neutrophils, basophils and eosinophils) and peripheral blood mononuclear cells (PBMCs - monocytes and lymphocytes). For this, blood samples from Nelore heifers will be collected on days 0 (IATF), 10, 14, 16, 18 and 20 after FTAI, and leukocytes will be isolated. The diagnosis of pregnancy will be performed on days 25 and 28 after insemination. Quantification of the target transcripts in this cell group will be done by polymerase chain reaction (RT-qPCR) after RNA extraction and complementary DNA synthesis. Expression of the type I interferon receptor transcripts will be compared between pregnant and non-pregnant females and peripheral blood mononuclear and polymorphonuclear cells. With the results of the present study, it is expected to observe a greater expression of type I interferon receptors in pregnant females, and that this expression will be more abundant from D16. It is also expected that no significant differences will be found between the expression of these receptors between PMNs and PBMCs.