Any process in which the symbiont modulates the frequency, rate or extent of receptor-mediated signal transduction in the host organism. The receptor is defined as a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand) such as a neurotransmitter or a hormone or other substance, and initiates the cellular response to the ligand. The host is defined as the larger of the organisms involved in a symbiotic interaction.