Babesias of red deer (Cervus elaphus) in Ireland

Abstract

Blood samples were obtained from 38 wild red deer (Cervus elaphus) at two sites in Ireland and subjected to PCR analysis of the 18S rRNA gene followed by sequencing. Two fragments of the 18S rRNA gene were generated by two different PCR protocols and subsequent sequencing suggested that at least six of the deer were infected by a babesia that, in those loci, is indistinguishable from Babesia divergens, an important tick-borne pathogen of cattle and of zoonotic significance. Additionally, a B. odocoilei-like parasite was detected in three samples and a babesia that did not match any sequences in the GenBank database was found in five samples. Neither B. capreoli nor B. venatorum (EU1) were found. There have been several reports of B. divergens occurring in deer species, including red deer, roe deer (Capreolus capreolus) and reindeer (Rangifer tarandus). However, in view of recent re-sequencing of bovine-origin samples deposited previously in GenBank, it is unlikely that any of these sequences from deer are B. divergens. The present study describes the only deer piroplasm detected so far that shows complete identity with B. divergens, in just over half of the 18S rRNA gene. The entire gene of this deer parasite should be analysed and transmission experiments undertaken before the infectivity of B. divergens for red deer can be confirmed.

Figure 1

Locations of sites where deer were sampled.

Figure 2

Phylogenetic relationships of deer Babesia species (present study in bold) according to the sequence amplified by PCR protocol I (bp loci 527-1005 in reference sequence AY046576*). The tree was constructed by sequence alignment of the 18S rRNA gene fragment and neighbour-joining analysis. Tree reliability was assessed by the bootstrap method with 1 000 pseudoreplicates (MEGA version 3.1, [14]). (*all amplicons exclude the primer sequences (as they are not part of the original DNA template) and approx. 40 bp at the 5' region for which there was insufficient over-lapping sequencing data).

Figure 3

Phylogenetic relationships of deer Babesia species (present study in bold) according to the sequence amplified by PCR protocol II (bp loci 1096-1589 in reference sequence AY046576*). The tree was constructed as described for Figure 2.