Investigation of the presence of Ochrobactrum spp. and Brucella spp. in Haemaphysalis longicornis.

Ticks are common vectors of human and animal diseases. Ochrobactrum spp. belong to the Brucellaceae family and have recently been recognized as emerging human pathogens. The ability of Haemaphysalis longicornis ticks to carry Ochrobactrum spp. remains uncertain. During June and July 2018, 686 ticks were collected from 11 sites in Pingdingshan Henan province in central China. We extracted 169 DNA samples for Brucellaceae 16S rRNA nested PCR and sequenced them in order to identify Ochrobactrum spp. The data sequences were aligned with NCBI BLAST program and phylogenetic tree was constructed using Mega 5.0. Twenty samples were sequenced successfully out of a total forty-one positive for Brucellaceae. Thirteen DNA samples were identical to O. intermedium (99.85 %-100.00 %) and 3 were identical to O. cicer (99.85 %-100.00 %) (15 collected from host and one from vegetation). Four DNA samples (3 collected from host and one from vegetation) had 99.83-100 % B. melitensis identity. This study adds to the growing body of evidence that shows Ochrobactrum spp. are present in H. longicornis. Ochrobactrum spp. and Brucella spp. are phenotypically and genetically closely related pathogens. Our finding highlights the importance of gene sequencing and phylogenetic analysis to differentiate between Ochrobactrum spp. and Brucella spp. in the research and potentially clinical setting. Future work is required to investigate the transmission potential of Ochrobactrum spp. by H. longicornis.