Upregulation of Coronavirus (MERS-CoV) Receptor Dipeptidyl Peptidase 4 on Camel Leukocytes After Bacterial Stimulation in vitro

Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging zoonotic pathogen which causes high mortality rate in humans. Dromedary camels may play a central role in virus transmission to humans. Dipeptidyl peptidase-4 (DPP4), a transmembrane protein located on the cell surface of many epithelial and endothelial tissues was identified as the receptor for MERS-CoV. The current study investigated the possibility that bacterial stimulation of camel blood could affect the expression level of DPP4 on camel leukocyte subpopulation, which in turn may contribute to the higher susceptibility of camels with bacterial infection to MERS-CoV infection. DPP4 expression was evaluated by membrane immunofluorescence and flow cytometry. Stimulation of camel blood with the bacterial species S. aureus or E. coli resulted in the upregulation of DPPV on both monocytes and granulocytes, while S. agalactiae did not significantly modulate DPPV expression on either of the immune cells (p > 0.05). None of the bacterial species could induce a change in DPPV expression on lymphocytes from stimulated blood. Collectively, the present study showed an enhancing effect of bacterial stimulation on DPPV expression on camel monocytes and granulocytes.