Proteomics approach to the study of cattle tick adaptation to white tailed deer

Abstract

Cattle ticks, Rhipicephalus (Boophilus) microplus, are a serious threat to animal health and production. Some ticks feed on a single host species while others such as R. microplus infest multiple hosts. White tailed deer (WTD) play a role in the maintenance and expansion of cattle tick populations. However, cattle ticks fed on WTD show lower weight and reproductive performance when compared to ticks fed on cattle, suggesting the existence of host factors that affect tick feeding and reproduction. To elucidate these factors, a proteomics approach was used to characterize tick and host proteins in R. microplus ticks fed on cattle and WTD. The results showed that R. microplus ticks fed on cattle have overrepresented tick proteins involved in blood digestion and reproduction when compared to ticks fed on WTD, while host proteins were differentially represented in ticks fed on cattle or WTD. Although a direct connection cannot be made between differentially represented tick and host proteins, these results suggested that differentially represented host proteins together with other host factors could be associated with higher R. microplus tick feeding and reproduction observed in ticks fed on cattle.

Figure 1

Proteomics characterization of ticks fed on cattle and WTD. (a) Number of peptides for tick and host proteins identified in ticks fed on cattle and WTD. (b) Proteins identified in ticks fed on cattle and WTD were functionally annotated and grouped according to their biological process. (c) Proteins identified in ticks fed on cattle and WTD were functionally annotated and grouped according to their molecular function. (d) Number of peptides for tick protein involved in blood digestion and reproduction identified in ticks fed on cattle and WTD. The number of peptides per protein on each pathway was represented as Ave + S.D. and compared between ticks fed on cattle and WTD by χ ² test (*P < 0.05). (e) Cathepsin L protein levels were determined by Western blot in R. microplus fed on cattle and WTD, quantified, and normalized against total proteins. Normalized protein levels (Ave + S.D. in arbitrary units) were compared between samples by Student's t-test (*P < 0.05; N = 2). MW: molecular weight markers.