Identification and Molecular Analysis of Ixodid Ticks (Acari: Ixodidae) Infesting Domestic Animals and Tick-Borne Pathogens at the Tarim Basin of Southern Xinjiang, China

Livestock husbandry is vital to economy of the Tarim Basin, Xinjiang Autonomous Region, China. However, there have been few surveys of the distribution of ixodid ticks (Acari: Ixodidae) and tick-borne pathogens affecting domestic animals at these locations. In this study, 3,916 adult ixodid ticks infesting domestic animals were collected from 23 sampling sites during 2012-2016. Ticks were identified to species based on morphology, and the identification was confirmed based on mitochondrial 16S and 12S rRNA sequences. Ten tick species belonging to 4 genera were identified, including Rhipicephalus turanicus, Hyalomma anatolicum, Rh. bursa, H. asiaticum asiaticum, and Rh. sanguineus. DNA sequences of Rickettsia spp. (spotted fever group) and Anaplasma spp. were detected in these ticks. Phylogenetic analyses revealed possible existence of undescribed Babesia spp. and Borrelia spp. This study illustrates potential threat to domestic animals and humans from tick-borne pathogens.

Selective expansion and enhanced anti-tumor effect of antigen-specific CD4(+) T cells by retrovirus-mediated IL-15 expression

Mounting evidence has demonstrated that CD4(+) T cells play an important role in anti-tumor immune responses. Thus, adoptive transfer of these cells may have great potential for anti-cancer therapy. However, due to the difficulty to generate sufficient tumor-specific CD4(+) T cells, the use of CD4(+) T cells in tumor therapy is limited. It has been found that IL-15 transfection enhances the proliferation and anti-tumor activity of tumor-specific CD8(+) T cells, but the effect of IL-15 transfection on CD4(+) T cells remains unknown. Here, the effects of retrovirus-mediated IL-15 expression in Ova-specific CD4(+) T cells from Do11.10 mice were evaluated and it was discovered that IL-15 transfected CD4(+) T cells expressed both soluble and membrane-bound IL-15. Retrovirus-mediated IL-15 expression led to a selective expansion of antigen-specific CD4(+) T cells by inhibiting their apoptosis. In vivo IL-15 transfected CD4(+) T cells were more effective in suppressing tumor growth than control retroviral vector transfected ones. To ensure the safety of the method, the employment of thymidine kinase gene made it possible to eliminate these transgenic CD4(+) T cells following ganciclovir treatment. Together, we show that IL-15 transfection induced a selective expansion of antigen-specific CD4(+) T cells ex vivo and enhanced their tumor-suppression effects in vivo. This has an important significance for improving the efficacy of adoptive T cell therapy.