Fig. 6.

A). Bidirectional immunoreactivity of HIV-1 gp140 immunized sera to the SARS-CoV-2 Spike. Serial dilutions of HIV-1 gp140 immunized rabbit sera were assessed for SARS-CoV-2 S protein binding. Milk coated wells were used as negative control in ELISA binding assay. B). Purified spike proteins were detected on Western blot by using gp140 immunized rabbit sera as primary antibody followed by using HRP conjugated anti Rabbit-Fc antibody. C). RBD-ACE2 competition assay suggests that HIV-1 polyclonal antibodies bind to RBD epitopes that are non-overlapping with ACE2 binding site. D). Spike protein was treated with PNGase and deglycosylated. The HIV-1 gp140 foldon immunized rabbit sera bound with both glycosylated and deglycosylated forms of spike protein. Statistical significance was determined using student t-test and p < 0.05 was considered significant and ns (non-significant).