Fractional calculus is one of the best mathematical tools to characterize the memory property of the dynamical systems. So, Variable-order fractional derivatives in Caputo sense are used in characterizing the memory property of the presented dynamic a vector host model. Numerical solutions are obtained using a predictor-corrector method to handle the fractional derivatives. These numerical solutions show that the modeling of vector host model with variable-order fractional derivatives has more advantaged than integer-order derivatives.