| Babesia is a group of tick-borne intracellular erythrocytic haemoprotozoan parasites infective to human and animals, belonging to the phylum Apicomplexa, class Sporozoea, order Piroplasmida, family Babesiidae and genus Babesia. Animals infected with Babesia will suffer from babesiosis, which is also known as tick fever, red water fever and so on. This disease is generally characterized by fever, anaemia, jaundice, haemoglobinuria and even death in serious conditions. The wide spread of this disease in tropical, subtropical and temperate regions of the world causes huge economic lose for livestock industry. The study of ovine babesiosis in China is late start and the pathogen species, distribution and biological characteristics of this disease are not very clear. In the present study, a molecular epidemiological investigation using the Real-time PCR of two Babesia species(Babesia motasi and Babesia sp.) was firstly performed, which were isolated from ten provinces of China. Besides, a physical map of Babesia sp. Xinjiang was constructed on the basis of a Bacterial Artificial Chromosome(BAC) library and genomic data sequenced using next- and third- generation sequencing(Solexa and PacBio RS II). This is a preliminary exploration research for understanding the distribution of this pathogen in China and structure genomic of ovine Babesia.To investigate and analyze the distribution of ovine Babesia in China, a total of 823 blood samples of sheep and goat covered in ten provinces were collected during 2010-2014. The genomic DNAs were extracted from these blood samples. A real-time PCR method that can differentiate B.motasi and Babesia sp. was used to detect the infection of ovine Babesia. Results showed that B. motasi was detected from nine provinces except Hainan province. The total positive rate was 5.95%(49/823) and the highest positive rate was present in the samples from Henan province, 10.47%(9/86). Babesia sp., however, was just detected in the samples from Hubei, Guizhou and Gansu provinces. The positive rate was 4.55%(2/44), 6.38%(3/47) and 0.62%(2/322), respectively. This is the first large-scale investigation for ovine babesiosis using real-time PCR in China. It provides the reliable molecular epidemiological information for further understanding of the distribution of ovine Babesia and developing prevention and control strategies of the diseases in this country.A total of 204 PCR primers were designed according to the genomic sequence data of Babesia sp. Xinjiang. 171 positive clones were obtained by amplification of 15,000 PCR and verification of DNA fingerprinting analysis of BAC. Finally five scaffolds clone overlapping map was successfully established on the basis of sequencing data. Total sizes were about 8.47 Mb and the coverage for genome reached 99%. However six pairs of primers in the scaffold were not screened positive clones. One pair of primers screened positive clones, but the actual size of the amplified fragment is different from that of desired size. This phenomenon may be caused by mis-assembling of the Babesia sp. Xinjiang genomic sequence data. The present study is a pre-exploratory research for further assembling accurate complete genomic sequence of Babesia sp.Xinag. |
