To determine the role of hr1 in the infection and receptor binding of ALV-A, hr1 was divided into six segments and replaced with the corresponding regions of ev-1 to construct a series of chimeric gp85 proteins s1–s6 and recombinant virus vectors RCASBP (A/E)-s1-s6-EGFP (Figure 2A). The gene discussed is CDCA7L; the disease is infection.