Subgroups B, D, and E avian leukosis viruses (ALV-B, -D, and -E) share the same chicken receptor, TVB^S1, a tumor necrosis factor receptor (TNFR)-related protein. These viruses, however, exhibit nonreciprocal receptor interference (NRI): cells preinfected with ALV-B or ALV-D are resistant to superinfection by viruses of all three subgroups, whereas those pre-infected by ALV-E are resistant only to superinfection by other subgroup E viruses. In this study, we investigated the basis of this phenomenon by characterizing the interaction of TVB^S1 with ALV-B Env or ALV-E Env. Sequential immunoprecipitation analysis using surface envelope immunoglobulin fusion proteins revealed the existence of two separate types of TVB^S1 that are encoded by the same cDNA clone. One form, designated the type 1 receptor, is specific for ALV-B and ALV-E. The other form, the type 2 receptor, is specific for ALV-B. We show that a protein consisting of only the first and second extracellular cysteine-rich domains of TVB^S1 is capable of forming both receptor types. However, the third extracellular cysteine-rich domain is required for efficient formation of the type 1 receptor. We also demonstrate that heterogeneous N-linked glycosylation cannot explain the difference in activities of the two receptor types. The existence of two types of TVB^S1 explains the NRI pattern between ALV-B and -E: subgroup B viruses establish receptor interference with both receptor types, whereas subgroup E viruses interfere only with the type 1 receptor, leaving the type 2 receptor available to mediate subsequent rounds of ALV-B entry. The formation of a TVB receptor type that is specific for cytopathic ALV may also have important implications for understanding how some subgroups of ALV cause cell death.