Establishment of equine and murine monocytic cell lines and their susceptibility to West Nile virus

Two monocytic cell lines, temporary named HsMo (horse monocyte) and MsMo (mouse monocyte) were established from blood samples of horse and Balb/C mouse according to the culture method previously informed (Kadoi, 2011). Tests were performed to certify the viral susceptibility of these cells in comparison with that of Vero cells for West Nile virus (WNV). Two strains of WNV adapted to grow in Vero cells were titrated for infectivity in the monocytic cells and Vero cells in a routine microplate assay system. The highest titer was obtained in the assay system with HsMo cells followed by the system with MsMo cells. These monocytic cells were sensitive enough for detecting WNV, however, WNV infected monocytes produced a strong acidic substance in which the acidity is much higher grade than that produced in Vero cells. In microplate culture the color of medium changes from redden neutral color to yellow indicated by phenol red dye included in cell culture medium, in parallel with CPE occurrence. This is a color test for WNV assay in monocytic cells