Genomic Study ofBabesia bovisInfection Level and Its Association With Tick Count in Hereford and Braford Cattle

Author(s)

Cavani, Ligia ^[1] ; Braz, Camila Urbano ^[1] ; Giglioti, Rodrigo ^[2] ; Okino, Cintia Hiromi ^[2] ; Gulias-Gomes, Claudia Cristina ^[3] ; Caetano, Alexandre Rodrigues ^[4] ; Oliveira, Marcia Cristina de Sena ^[2] ; Cardoso, Fernando Flores ^[3] ; Oliveira, Henrique Nunes de ^[1]

Affiliation

^[1] Sao Paulo State Univ Unesp, Sch Agr & Vet Sci, Jaboticabal - Brazil

^[2] Empresa Brasileira Pesquisa Agr, Embrapa Pecuaria Sudeste, Sao Carlos - Brazil

^[3] Empresa Brasileira Pesquisa Agr, Embrapa Pecuaria Sul, Bage - Brazil

^[4] Empresa Brasileira Pesquisa Agr, Embrapa Recursos Genet & Biotecnol, Brasilia, DF - Brazil

• Document type: Journal article
• Source: FRONTIERS IN IMMUNOLOGY; v. 11, AUG 28 2020.
• Web of Science Citations: 1

Abstract

Bovine babesiosis is a tick-borne disease caused by intraerythrocytic protozoa and leads to substantial economic losses for the livestock industry throughout the world.Babesia bovisis considered the most pathogenic species, which causes bovine babesiosis in Brazil. Genomic data could be used to evaluate the viability of improving resistance againstB. bovisinfection level (IB) through genomic selection, and, for that, knowledge of genetic parameters is needed. Furthermore, genome-wide association studies (GWAS) could be conducted to provide a better understanding of the genetic basis of the host response toB. bovisinfection. No previous work in quantitative genetics ofB. bovisinfection was found. Thus, the objective of this study was to estimate the genetic correlation between IB and tick count (TC), evaluate predictive ability and applicability of genomic selection, and perform GWAS in Hereford and Braford cattle. The single-step genomic best linear unbiased prediction method was used, which allows the estimation of both breeding values and marker effects. Standard phenotyping was conducted for both traits. IB quantifications from the blood of 1,858 animals were carried using quantitative PCR assays. For TC, one to three subsequent tick counts were performed by manually counting adult female ticks on one side of each animal's body that was naturally exposed to ticks. Animals were genotyped using the Illumina BovineSNP50 panel. The posterior mean of IB heritability, estimated by the Bayesian animal model in a bivariate analysis, was low (0.10), and the estimations of genetic correlation between IB and TC were also low (0.15). The cross-validation genomic prediction accuracy for IB ranged from 0.18 to 0.35 and from 0.29 to 0.32 using k-means and random clustering, respectively, suggesting that genomic predictions could be used as a tool to improve genetics for IB, especially if a larger training population is developed. The top 10 single nucleotide polymorphisms from the GWAS explained 5.04% of total genetic variance for IB, which were located on chromosomes 1, 2, 5, 6, 12, 17, 18, 16, 24, and 26. Some candidate genes participate in immunity system pathways indicating that those genes are involved in resistance toB. bovisin cattle. Although the genetic correlation between IB and TC was weak, some candidate genes for IB were also reported in tick infestation studies, and they were also involved in biological resistance processes. This study contributes to improving genetic knowledge regarding infection byB. bovisin cattle. (AU)

• FAPESP's process: 16/07216-7 - Genomic study and immunological characterization of cattle resistant to bovine babesiosis and analysis of the genetic diversity of Babesia bovis and Babesia bigemina
• Grantee: Henrique Nunes de Oliveira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 15/13024-0 - Genomic study on infection rate of Babesia bovis and association with resistance of tick in Hereford and Braford cattle
• Grantee: Ligia Cavani
• Support Opportunities: Scholarships in Brazil - Doctorate