Guiquan Guan

Abstract :

Ovine Babesiosis caused by genus Babesia, is a tick-born haemoprotozoan disease. In this study, Chinese ovine Babesia strains, especially Babesia sp. BQ1 (Lintan) and Babesia sp. Xinjiang have been characterized biologically and molecularly. Based on Hsp90 gene sequences and cross-reactions, these Babesias could be separated into 2 groups, Babesia sp. Xinjiang group and B. motasi-like group which could be further divided into two subgroups, pathogenic subgroup and non-pathogenic subgroup. Experimental transmissions verify that vector ticks of Babesia sp. BQ1 (Lintan) are Haemaphysalis qinghaiensis and H. longicornis and that of Babesia sp. Xinjiang is Hyalomma anatolicum anatolicum. On the basis of evidence from molecular phylogeny and biological characteristics, Babesia sp. Xinjiang should be a novel Babesia species. Studies of susceptibility of two sheep breeds to each Babesia sp. BQ1 (Lintan) and B. divergens indicated that host genetic resistance and individual susceptibility to Babesia spp. have relationship with ability of erythrocytes to sustain multiplication of the parasites. Test of immune responses reveals IFNγ is associated with lower infectivity of B. divergens and IL10 with higher infectivity of Babesia sp. BQ1 (Lintan) to sheep. Three detection methods for Babesia sp. BQ1 (Lintan) or Babesia sp. Xinjiang infection have been developed, in vitro culture, Loop-mediated Isothermal Amplification (LAMP) and indirect enzyme-linked immunosorbent assay (ELISA) that could provide different information about the infection. Potentially diagnostic antigens identified, such as BQHsp90, BQp35, Hsp70, p200, are promising in application of serological diagnosis in future.