Anaplasma capra, a species of the family Anaplasmataceae, is zoonotic tick-borne obligate intracellular bacteria. There have been no reports of human infection with this pathogen since 2015. Therefore, the zoonotic characteristics of A. capra need to be further studied. To verify the ability of A. capra to infect human cells, A. capra were inoculated in human erythrocytes, HL-60, and TF-1 cell lines in vitro. Cell smears were taken after inoculation, using Giemsa staining, transmission electron microscope (TEM), chromogenic in situ hybridization and immunocytochemistry for detection. In the Giemsa staining, many dark colored corpuscles or purple granules were seen in the inoculated erythrocytes, HL-60, and TF-1 cells. The results of chromogenic in situ hybridization show that there were brown precipitates on the surface of most erythrocytes. Immunocytochemistry results show many dark brown vacuolar structures or corpuscles in the cytoplasm of erythrocytes, HL-60, and TF-1 cell lines. The A. capra morulae were seen in the cytoplasm of both HL-60 and TF-1 in TEM, and their diameter was about 295–518 nm. Both dense-cored (DC) and reticulate cell (RC) form morulae could be seen. This study confirmed the ability of A. capra to infect human erythrocytes, HL-60, and TF-1. This study is of profound significance in further verifying the zoonotic characteristics of the pathogen and for establishing an in vitro cultivation model.

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Giardia duodenalis is a common zoonotic intestinal parasitic protozoan and sheep are among its hosts; however, limited information is available on sheep kept in large-scale housing. The Hu sheep is a first-class protected local livestock breed in China. In this study, we investigated the seasonal dynamics of G. duodenalis infection in Hu sheep and the environmental contamination of large-scale sheep farms. We collected 474 fecal samples and 312 environmental samples from Hu sheep on a large-scale sheep farm in Henan, China. The prevalence of G. duodenalis was determined by nested PCR targeting the β‑giardin (bg) gene. The assemblages and multilocus genotypes (MLGs) were investigated based on analyses of three genetic loci, i.e. bg, glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi). To detect mixed infections of different assemblages, assemblage A/E-specific PCRs were performed to amplify the tpi gene. The prevalence of G. duodenalis infection in sheep was 17.9% (81/474) and the positivity rate in environmental samples was 0.96% (3/312). Genetic analysis revealed the presence of two assemblages (assemblages A and E), with assemblage E being detected in both fecal and environmental samples, and assemblage A detected only in fecal samples. A total of 23 MLGs were obtained in fecal and environmental samples, all of which belonged to assemblage E. These results indicate the seasonal dynamics of G. duodenalis infection in sheep and environmental contamination on large-scale housing sheep farms and provide an important reference for the prevention and control of G. duodenalis on large-scale housing sheep farms.