Anaplasmaspecies are obligate intracellular rickettsial pathogens that impact the health of humans and animals. Few studies have been carried out onAnaplasmainfections in central and southern China. This study was conducted to determine the coinfection rates ofAnaplasma ovis,A. bovis, andA. phagocytophilumfrom 262 field blood samples of goats in these regions. The average prevalences of single infection ofA. ovis,A. bovis, andA. phagocytophilumwere 15.3, 16.0, and 6.1%, respectively. Coinfection ofA. ovisandA. boviswas dominant, with an infection rate of 27.1%. Coinfection ofA. ovisandA. phagocytophilumwas 1.9% and that ofA. bovisandA. phagocytophilumwas 4.2%. Three-pathogen coinfection was found in three of four investigated provinces with a prevalence between 0 and 5.3%. The accuracy of the PCR results was corroborated by sequencing. Analysis of the 16S rRNA gene sequences ofA. bovisandA. phagocytophilumconfirmed the presence of these pathogens at the investigated sites and indicated the possible genetic diversity ofA. phagocytophilum. Field blood inoculation of experimental animals led to successful identification and observation of the morphological shapes ofA. bovisin the infected monocytes of sheep. Phylogenetic study withmsp4sequences ofA. ovisindicated that theA. ovisgenotypes from sheep in the north differed from the genotypes of goats in the investigated sites.

Foot-and-mouth disease virus (FMDV) causes a highly contagious infection in cloven-hoofed animals. The format of FMD virus-like particles (VLP) as a non-replicating particulate vaccine candidate is a promising alternative to conventional inactivated FMDV vaccines. In this study, we explored a prokaryotic system to express and assemble the FMD VLP and validated the potential of VLP as an FMDV vaccine candidate. VLP composed entirely of FMDV (Asia1/Jiangsu/China/2005) capsid proteins (VP0, VP1 and VP3) were simultaneously produced as SUMO fusion proteins by an improved SUMO fusion protein system in E. coli. Proteolytic removal of the SUMO moiety from the fusion proteins resulted in the assembly of VLP with size and shape resembling the authentic FMDV. Immunization of guinea pigs, swine and cattle with FMD VLP by intramuscular inoculation stimulated the FMDV-specific antibody response, neutralizing antibody response, T-cell proliferation response and secretion of cytokine IFN-γ. In addition, immunization with one dose of the VLP resulted in complete protection of these animals from homologous FMDV challenge. The 50% protection dose (PD₅₀) of FMD VLP in cattle is up to 6.34. These results suggest that FMD VLP expressed in E. coli are an effective vaccine in guinea pigs, swine and cattle and support further development of these VLP as a vaccine candidate for protection against FMDV.

Anaplasmosis is caused by obligate intracellular bacteria in the genus Anaplasma. These bacterial pathogens are transmitted by ticks and impact both human and animal health. This study was conducted to determine the prevalence and molecular characterization of Anaplasma spp. in ruminants sampled in Xinjiang, northwest China. A survey was performed in August 2012 in rural areas of six counties in Xinjiang province. A total of 250 blood samples from ruminants were collected and tested for the presence of Anaplasma spp. by PCR. Positive samples were genetically characterized based on the 16S rRNA and msp4 genes. The results showed a high prevalence of Anaplasma spp. in ruminants, with at least three different Anaplasma species detected (A. phagocytophilum, A. bovis and A. ovis). The mean prevalence of single infection with each species was 17.6% (A. phagocytophilum), 4.8% (A. bovis) and 40.5% (A. ovis). Coinfection occurred in 20 (8.0%) animals. Phylogenetic analysis of the 16S rRNA gene of A. bovis and A. phagocytophilum revealed a higher degree of genetic diversity for the latter. The results for A. ovis showed genotypic variation among geographic regions in China. In addition, a closely related isolate to the canine pathogen A. platys was identified in ruminants. This survey revealed a high prevalence of Anaplasma sp. infections in sheep and cattle in the northwestern border regions of China, indicating the potential risk of transboundary disease.

Toxoplasma gondii is an obligate intracellular parasitic protozoan that has a wide host range and causes a zoonotic parasitosis called toxoplasmosis. This infection causes significant morbidity, costs for care and loss of productivity and suffering. The most effective measures to minimize this parasite’s harm to patients are prompt diagnosis and treatment and preventing infection. A parasite surface antigen, SAG1, is considered an important antigen for the development of effective diagnostic tests or subunit vaccines. This review covers several aspects of this antigen, including its gene structure, contribution to host invasion, mechanisms of the immune responses and its applications for diagnosis and vaccine development. This significant progress on this antigen provides foundations for further development of more effective and precise approaches to diagnose toxoplasmosis in the clinic, and also have important implications for exploring novel measures to control toxoplasmosis in the near future.

Anaplasma spp. are tick-transmitted bacteria that infect a wide variety of wild and domestic animals. These pathogens exhibit a high degree of biological diversity, broad geographical distribution, and represent a serious threat to veterinary and public health worldwide. A novel Anaplasma species was identified in Haemaphysalis qinghaiensis (Ixodidae) in northwestern China and was molecularly characterized by comparison of 16S rRNA, gltA, and groEL gene sequences. Of the 414 samples tested, 24 (5.8%) were positive for this Anaplasma species. On the basis of the 16S rRNA gene, this organism has been found to be closely related to and exhibit the highest sequence similarity with A. capra (99.8–99.9%) that was identified in goats and humans in northern China, but was distinct from other known Anaplasma species. Sequence analysis of the gltA and groEL genes revealed that this Anaplasma species was distinct from A. capra considering the lower sequence identity (88.6–88.7% for gltA and 90.6–91.0% for groEL) and a divergent phylogenetic position. Therefore, we described this Anaplasma species as A. capra-like bacteria. The present study reports a potential novel Anaplasma species closely related to A. capra in H. qinghaiensis in northwestern China. The zoonotic potential of A. capra-like bacteria needs to be further determined.

Tick-borne diseases currently represent an important issue for global health. A number of emerging tick-transmitted microbes continue to be discovered, and some of these are already identified as the cause of human infections. Over the past two decades, Anaplasma phagocytophilum is considered to be mainly responsible for human anaplasmosis. However, a novel zoonotic pathogen provisionally named “Anaplasma capra” has recently been identified in China. In this study, we did an active surveillance of A. capra in goats and sheep in different geographical regions of China. The presence of A. capra was determined by nested PCR in 547 blood samples collected from goats and sheep from 24 counties distributed in 12 provinces in China. The molecular characterization of A. capra isolates in sheep and goats was achieved based on four conventional genetic markers (16S rRNA, gltA, groEL and msp4 genes). Anaplasma capra was identified in 75 of 547 animals, with an overall prevalence of 13.7%. The infection rates in the survey sites ranged from 0 to 78.6%, and were significantly different (P < 0.01). Phylogenetic analysis revealed that the isolates obtained from goats, sheep, Ixodes persulcatus ticks and humans create a separate clade within the genus Anaplasma and distinct from other recognized Anaplasma species. These findings indicated that these A. capra isolates possess the same molecular characteristics, suggesting that this organism could be a substantial health threat to both animals and humans. Anaplasma capra is an emerging tick-transmitted zoonotic pathogen. This novel Anaplasna species is widespread across China with an overall prevalence of 13.7% in goats and sheep with isolates indistinguishable from those found in humans. These findings warrant increased public health awareness for human anaplasmosis.