Isolation and characterization of Babesia pecorum sp. nov. from farmed red deer (Cervus elaphus)

Abstract

The diversity of Babesia species infecting cervids in parts of central and southern Spain was analyzed by collecting blood from farmed red deer (Cervus elaphus). Babesia sp. was isolated in vitro from two red deer herds in Cádiz and Ciudad Real. The number of Babesia sp. carriers differed between the two herds: 36/77 in Cádiz and 1/35 in Ciudad Real. Hyalomma lusitanicum was the most prevalent tick species identified on the Cádiz farm vegetation and on sampled animals, and is therefore a candidate vector. The molecular characteristics of 21 isolates were determined by complete (8 isolates) or partial (13 isolates) 18S rRNA gene sequencing. The sequences were highly similar (over 99.4% identity) and 6 sequence types were identified at the level of one herd only, demonstrating a rather high genetic diversity. They formed a monophyletic clade, and members of the three main sequence types shared a similar morphology and the same erythrocyte susceptibility pattern. This clade also included Babesia sp. Xinjiang isolated from sheep in China and Babesia sp. identified in giraffe in South Africa, with identities higher than 98.3% and statistically relevant phylogenetic support. None of the biological properties analyzed for both Babesia from red deer and Babesia sp. Xinjiang allowed their differentiation (ability to develop in vitro in erythrocytes from cattle and sheep, as well as in erythrocytes from different cervids, unsuccessful infection of calves). We propose the Babesia isolated from red deer as a new species named B. pecorum. Whether Babesia sp. Xinjiang and the Babesia characterized in South Africa belong to the same species is debated.