Individual Animal Serological Test Results From Antibody Screening of Tanzanian Dairy Cattle to Brucellosis, Leptospirosis, Q Fever, Rift Valley Fever, Neospora Caninum, and Toxoplasma Gondii

Data from paper provisionally accepted in Frontiers Genetics - Livestock Genomics. Research topic Advances in Livestock Genetics: Enhancing Breeding Practices and Improving Animal Health.

"Genetic estimates and genome-wide association studies of antibody responses in Tanzanian dairy cattle." Luis E Hernandez-Castro, Elizabeth Anne Jessie Cook, Oswald Matika, Isaac Joseph Mengele, Shabani Kiyabo Motto, Shedrack Festo Bwatota, Bibiana Zirra-Shallangwa, Ricardo Pong-Wong, James Prendergast, Raphael Mrode, Philip G Toye, Daniel Mushumbusi Komwihangilo, Eliamoni Lyatuu,Benedict E Karani, Getrude Nangekhe, Okeyo Ally Mwai, Gabriel Mkilema Shirima, and Barend Mark de Clare Bronsvoort.

Identifying the genetic determinants of host defence against infectious pathogens is central to enhancing disease resilience and therapeutic efficacy in livestock. Here, we investigated immune response heritability to important infectious diseases affecting dairy smallholder cattle using variance component analysis. We also conducted genome-wide association studies (GWAS) to identify genetic variants that may help understand the underlying biology of these health traits. Assessing 668,911 single-nucleotide polymorphisms (SNP) genotyped in 2045 crossbreed cattle sampled from six regions of Tanzania, we identified high levels of interregional admixture and European introgression, which may increase infectious disease susceptibility relative to indigenous breeds. Heritability estimates were low to moderate, ranging from 0.03 (SE ± 0.06) to 0.44 (SE ± 0.07), depending on the health trait. GWAS results revealed several loci associated with seropositivity to the viral diseases Rift Valley fever and bovine viral diarrhoea, the protozoan parasites Neospora caninum and Toxoplasma gondii, and the bacterial pathogens Brucella sp, Leptospira hardjo and Coxiella burnetti. The identified quantitative trait loci mapped to genes involved in immune defence, tumour suppression, neurological processes, and cell exocytosis. We propose that our results form a baseline in the future understanding of the cellular pathways contributing to general and taxon-specific infection responses, and to advance selective breeding and therapeutic target designs.

The serological response trait was obtained for each individual animal through testing for antibody response to seven pathogens using commercial ELISA kits of bovine viral diarrhoea virus (ID Screen® BVD p80 Antibody Competition, Innovate Diagnostics, France), Neospora caninum (ID Screen® Neospora caninum Competition, Innovate Diagnostics, France), Leptospira hardjo (Leptospira interrogans subtype Hardjoprajitno and Leptospira borgpetersenii subtype Hardjobovis; The Linnodee Leptospira Hardjo ELISA KitTM, Linnodee Animal Care, UK), Rift Valley fever virus (ID Screen® Rift Valley Fever Competition Multi-species, Innovate Diagnostics, France), Toxoplasma gondii (ID Screen® Toxoplasmosis Indirect Multi-species, Innovate Diagnostics, France), Coxiella burnetii (Q fever; PrioCHECKIT™ Ruminant Q Fever Ab Plate Kit, Thermofisher Scientific, USA) and Brucella abortus (COMPELISA 160 & 400, APHA Scientific, UK). Following manufacturer guidelines. All optical density (OD) values were transformed into a binary seropositive seronegative classification based on the manufacturers recommended cut-offs.