The research is devoted to the construction of operators of relativistic interactions in the meson-nucleon systems in the clothed-particle representation. A new recursive method to satisfy the algebra of commutation relations between the generators of the Poincaré group is offered. The operators of relativistic interactions in a model with pseudoscalar Yukawa-type coupling in the second and third order in the coupling constant are constructed. Vertex orrection in the third order in Yukawa model is calculated. Nonlocal interactions in Wentzel model in the second order in the coupling constant in the Hamiltonian and boost operators are obtained. Analytical expressions in the nonlocal Wentzel model, which determine the mass shifts in the second order in the coupling constant are obtained and their dependence on the momentum of a clothed particle is investigated. Research for scientific degree of candidate of science in physics and mathematics by speciality 01.04.02 - theoretical physics.