Figure 1.

Comparative binding assays of virus particles bearing the Env protein of FeLV-A/61E or of FeLV-945. A. Feline 3201 cells were incubated with equivalent numbers of virus particles bearing the envelope protein of FeLV-A/61E (61E Env) or FeLV-945 (945 Env), followed by incubation with monoclonal antibody C11D8 to detect the surface-bound viral SU protein and then with an Alexa Fluor 488-conjugated secondary antibody. Virus binding was analyzed by flow cytometry. A representative histogram is shown, demonstrating the binding activity of the particles as indicated and a negative control in which no virus was included in the assay (shaded). B. The geometric mean fluorescence of quadruplicate samples from individual assays is indicated, as is the mean of replicate experiments (horizontal bar). Asterisk indicates statistical significance (*; p < 0.001).