The mechanisms underlying tick resistance within and between cattle breeds have been
studied for decades. Several previous papers on bovine immune parameters contributing
to tick resistance discussed findings across DNA, RNA, protein, cellular, and tissue levels.
However, the differences between bovine host species, tick species and the experimental
layouts were not always taken into account. This review aims to (a) give a comprehensive
summary of studies investigating immune marker differences between cattle breeds
with varying degrees of tick resistance, and (b) to integrate key findings and suggest
hypotheses on likely immune-regulated pathways driving resistance. Experimental
issues, which may have skewed conclusions, are highlighted. In future, improved
experimental strategies will enable more focused studies to identify and integrate
immune markers and/or pathways. Most conclusive thus far is the involvement of
histamine, granulocytes and their associated pathways in the tick-resistancemechanism.
Interestingly, different immune markers might be involved in the mechanisms within a
single host breed in contrast to between breeds. Also, differences are evident at each
tick life stage, limiting the level to which datasets can be compared. Future studies to
further elucidate immune molecule dynamics across the entire tick life cycle and in-depth
investigation of promising markers and pathways on both molecular and cellular level are
in dire need to obtain a scientifically sound hypothesis on the drivers of tick resistance.
Supplementary Table 1 | Summary of studies investigating tick resistance/
susceptibility categorized according to tissue of study.