Anti-OVA polyclonal antibody [Biotin]

The CD8+ T cell response to the intracellular parasiteToxoplasma gondiivaries dramatically between mouse strains, resulting in stark differences in control of the parasite. Protection in BALB/c mice can be attributed to an unusually strong and protective MHC-1 L-d-restricted CD8+ T cell response directed against a peptide derived from the parasite antigen GRA6. The MHC-1 L(d)molecule has limited peptide binding compared to conventional MHC molecules such as K(b)or D-b, which correlates with polymorphisms associated with "elite control" of HIV in humans. To investigate the link between the unusual MHC-1 molecule L(d)and the generation of "elite controller" CD8+ T cell responses, we compared the GRA6-L(d)specific T cell response to the well-studied OVA-K(b)specific response, and demonstrated that GRA6-L(d)specific T cells are significantly more protective and resistant to exhaustion in chronicT. gondiiinfection. To further investigate the connection between limited peptide presentation and robust T cell responses, we used CRISPR/Cas9 to generate mice with a point mutation (W97R) in the peptide-binding groove of L(d)that results in broader peptide binding. We investigated the effect of this L(d)W97R mutation on another robust L-d-restricted response against the IE1 peptide during Murine Cytomegalovirus (MCMV) infection. This mutation leads to an increase in exhaustion markers in the IE1-L(d)specific CD8+ T cell response. Our results indicate that limited peptide binding by MHC-1 L(d)correlates with the development of robust and protective CD8+ T cell responses that may avoid exhaustion during chronic infection.

Theileria annulata is a protozoan parasite transmitted by ticks to cattle. The most important processes of T. annulata are the infection and transformation of host monocytes, which promote cell division and generate a neoplastic phenotype. Dendritic cells play an important role in the development of adaptive immune responses against parasites and are traditionally classified into four types. One type of dendritic cell derived from afferent lymph was successfully transformed by T. annulata in vitro in a previous report. However, whether the monocyte-derived dendritic cells could be transformed and how the endocytic function is affected by T. annulata infection were not yet known. Bovine dendritic cells (DCs) derived from blood CD14(+) monocytes were co-cultured with T. annulata sporozoites in vitro. On day 15 post infection, rounded and continuously proliferating cells were observed. The effect of this transformation on cell phenotype was studied using immunostaining and flow cytometry. After transformation, the cells maintained the expression of the DC-specific marker CD11c, but it was downregulated as were the expression of CD11b, CD14 and CD86. In contrast, CD205, CD45 and MHC class. molecules were upregulated in transformed cells. The levels of CD172a, CD21, CD40 and CD80 expression were very low in the transformed cells (< 1 %). However, the transformed cells maintained high expression levels of MHC. (> 99 %). In addition, the normal and transformed DCs were cocultured with OVA-FITC antigen to compare the differences of the endocytic functions between these two types of cells. The results revealed that the endocytic functions of MoDCs were significantly inhibited after transformation by T. annulata.