Towards a new phenotype for tick resistance in beef and dairy cattle: a review

Burrow, H. M.; Mans, Ben J.; Cardoso, F. F.; Birkett, Michael A.; Kotze, Andrew C.; Hayes, Ben J.; Mapholi, Ntanganedzeni O.; Dzama, K.; Marufu, Munyaradzi Christopher; Githaka, Naftaly; Djikeng, Appolinaire

doi:10.1071/an18487

Cited by 50 publications

(57 citation statements)

References 195 publications

(247 reference statements)

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“…trypanosomosis, bovine malignant catarrhal fever, East Coast fever, and Rift Valley fever) would have represented major constraints to the dispersion of indicine x taurine crossbred cattle 22 . Here, the tolerance of African taurine cattle to trypanosomosis 4 as well as the resistance of indicine cattle to infestation with ticks and to heat stress have proven advantageous [72][73][74] .…”

Section: Discussionmentioning

confidence: 99%

The mosaic genome of indigenous African cattle as a unique genetic resource for African pastoralism

Kim

Kwon

Dessie³

et al. 2020

Nat Genet

129

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EAT and AAI, along eigenvector 1, which explains ~15% of the total variation. AFT Muturu and N'Dama are close to EAT along the eigenvector 1. Most of the AFH cattle cluster together regardless of their breed memberships, leaving only Ankole, Mursi and Sheko outside the main cluster toward the AFT Muturu and N'Dama. The PCA results also show that Muturu and N'Dama, our representative of AFT population, are separated from the other cattle groups (eigenvector 2, ~2.5% of total variation). Sheko positions close to the AFH, as similarly reported in other studies 5,43 . Genetic clustering analysis using ADMIXTURE 44 corroborates the pattern found in PCA (Fig. 2b and Extended Data Fig. 2). Most of AFH show a similar proportion of taurine ancestry, around 25% on average. Only a few AFH breeds have elevated taurine ancestry: Ankole (53.37 ± 1.49%), Sheko (46.28 ± 2.03%) and Mursi (35.90 ± 2.16%). (Fig. 2b).Genetic distance and diversity. Pairwise F st were calculated to estimate the genetic distances between populations (n = 38) (Extended Data Fig. 3). Taurine (EUT, AST and AFT) show F st values of 0.1568 and 0.3287 on average against AFH and AAI, respectively.Across AFH, pairwise F st between breeds is close to zero, regardless of their phenotypic classification as African Zebu, Sanga or Zenga. Muturu and N'Dama show F st value of 0.1769, 0.1847 and 0.3734 against AFH, EAT and AAI, respectively.The genome-wide autosomal SNPs show reduced levels of heterozygosity in the taurine (0.0021 ± 0.0005/bp) compared to all other populations (0.0048 ± 0.0008/bp). Heterozygosity values of AFH are similarly higher across populations (0.0046 ± 0.0003/bp). AAI shows a higher level of heterozygosity compared to AFH (0.0052 ± 0.0014/bp) (Extended Data Fig. 4). The degree of inbreeding measured by runs of homozygosity (ROH) shows that taurine, including Muturu and N'Dama, have a higher level of inbreeding compared to the other and Ethiopia), the University of Khartoum (Sudan), and the National Biotechnology Development Agency (NABDA) (Nigeria). The following institutions and their personnel provided help for the sampling of the African cattle: ILRI Kapiti Ranch, Ministry of Animal Resources, Fisheries and Range (Sudan), Ol Pejeta Conservancy (Kenya), Institute of Biodiversity (Ethiopia), the Directors of Veterinary Services and the cattle keepers from Ethiopia, Kenya, Uganda and Sudan. ILRI livestock genomics program is supported by the

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Section: Discussionmentioning

confidence: 99%

The mosaic genome of indigenous African cattle as a unique genetic resource for African pastoralism

Kim

Kwon

Dessie³

et al. 2020

Nat Genet

129

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“…The Rhipicephalus ( B. ) microplus complex is found on all major continents including North America, South America, Africa, Asia and Australia [2]. Members of the complex include R. ( B. )…”

Section: Introductionmentioning

confidence: 99%

Investigation into limiting dilution and tick transmissibility phenotypes associated with attenuation of the S24 vaccine strain

et al. 2019

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Background Babesia bovis is the causal agent of Asiatic redwater, transmitted by the pandemic tick Rhipicephalus ( Boophilus ) microplus . Disease control may target the tick vector using acaricides or anti-tick vaccines, or the parasite using chemoprophylaxis or anti-parasite vaccines. Current anti-parasite vaccines comprise live blood vaccines using attenuated B. bovis strains. Attenuation is attained by rapid passage that may result in different phenotypes such as reduced virulence, non-transmissibility by the tick vector, inability to sequester in the host (lack of limiting dilution) and limited genetic diversity. Attenuation and phenotypes may be linked to selection of subpopulations during rapid passage. The South African B. bovis S24 vaccine strain comprise a subpopulation that present low virulence, non-transmissibility, lack of limiting dilution phenotype and the presence of a single A558 Bv80 allele. The S24 strain could be co-transmitted with a field strain (05-100) suggesting sexual recombination. The present study investigated the change in phenotype for the S24 vaccine strain during rapid passage and co-transmission. Methods Vaccine phenotype change during passage as well as co-transmissibility was monitored using Bv80 allele specific PCR, limiting dilution and Illumina-based genome sequencing. Results The S24 population could not be rescued from the S16 passage as previously attained suggesting that selection of the S24 vaccine strain was a serendipitous and stochastic event. Passage from S16 to S24 also resulted in loss of the limiting dilution phenotype. Genome sequencing indicated sexual recombination during co-transmission with the 05-100 field strain. Analysis of the recombinant strain indicate that VESA1, smORF and SBP2 family members are present and may be responsible for the limiting dilution phenotypes, while various regions may also be responsible for the tick transmission phenotype. Conclusions The molecular basis for tick transmission and limiting dilution phenotypes may be defined in future using selection based on these traits in combination with sexual recombination.

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“…For example there are multi-host tick species in South Africa [e.g. ( 3 )] that are not present in either Brazil or Australia, so the counts may simply be a reflection of those different tick species possibly having different mechanisms of resistance ( 42 ).…”

Section: Resultsmentioning

confidence: 99%

“…Another factor that could also explain this lower accuracy of prediction for NG could be the time and body location of counting. In the Australian and Brazilian data, tick counts only occurred at times of the year when there was large phenotypic variation and assessing one whole side of the animal, while for the NG population perineum counts occurred throughout the year and the averaged data used in the present study included counting times that would not meet the phenotyping requirement of at least 20 ticks per side of each animal, averaged over at least 15 animals ( 42 ). Therefore, additional phenotyping and genotyping must be pursued within this breed before practical genomic selection can be implemented to increase its tick resistance.…”

Section: Resultsmentioning

confidence: 99%

Multiple Country and Breed Genomic Prediction of Tick Resistance in Beef Cattle

et al. 2021

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Ticks cause substantial production losses for beef and dairy cattle. Cattle resistance to ticks is one of the most important factors affecting tick control, but largely neglected due to the challenge of phenotyping. In this study, we evaluate the pooling of tick resistance phenotyped reference populations from multi-country beef cattle breeds to assess the possibility of improving host resistance through multi-trait genomic selection. Data consisted of tick counts or scores assessing the number of female ticks at least 4.5 mm length and derived from seven populations, with breed, country, number of records and genotyped/phenotyped animals being respectively: Angus (AN), Brazil, 2,263, 921/1,156, Hereford (HH), Brazil, 6,615, 1,910/2,802, Brangus (BN), Brazil, 2,441, 851/851, Braford (BO), Brazil, 9,523, 3,062/4,095, Tropical Composite (TC), Australia, 229, 229/229, Brahman (BR), Australia, 675, 675/675, and Nguni (NG), South Africa, 490, 490/490. All populations were genotyped using medium density Illumina SNP BeadChips and imputed to a common high-density panel of 332,468 markers. The mean linkage disequilibrium (LD) between adjacent SNPs varied from 0.24 to 0.37 across populations and so was sufficient to allow genomic breeding values (GEBV) prediction. Correlations of LD phase between breeds were higher between composites and their founder breeds (0.81 to 0.95) and lower between NG and the other breeds (0.27 and 0.35). There was wide range of estimated heritability (0.05 and 0.42) and genetic correlation (-0.01 and 0.87) for tick resistance across the studied populations, with the largest genetic correlation observed between BN and BO. Predictive ability was improved under the old-young validation for three of the seven populations using a multi-trait approach compared to a single trait within-population prediction, while whole and partial data GEBV correlations increased in all cases, with relative improvements ranging from 3% for BO to 64% for TC. Moreover, the multi-trait analysis was useful to correct typical over-dispersion of the GEBV. Results from this study indicate that a joint genomic evaluation of AN, HH, BN, BO and BR can be readily implemented to improve tick resistance of these populations using selection on GEBV. For NG and TC additional phenotyping will be required to obtain accurate GEBV.

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Towards a new phenotype for tick resistance in beef and dairy cattle: a review

Cited by 50 publications

References 195 publications

The mosaic genome of indigenous African cattle as a unique genetic resource for African pastoralism

The mosaic genome of indigenous African cattle as a unique genetic resource for African pastoralism

Investigation into limiting dilution and tick transmissibility phenotypes associated with attenuation of the S24 vaccine strain

Multiple Country and Breed Genomic Prediction of Tick Resistance in Beef Cattle

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