Fig. 3.

The effect of alanine residues in positions 554–556 and 546/548 on S protein molecular mimicry of FcγRII. Immunoprecipitation of DBT cells infected with the recombinant viruses rA59/S (546/548) (Panel A) and rA59/S (554–556) (Panels B and C). DBT cells were mock infected, infected with either the isogenic control virus rA59/S(pMH54), or infected with a recombinant virus containing a mutation in S. The cells were incubated until CPE was apparent at 8 hpi and metabolically labeled with [³⁵S]- methionine and cysteine for one hour, after which lysates were prepared and immunoprecipitated with the monoclonal anti-FcγRII antibody 2.4G2 as described in Materials and Methods. S uncleaved denotes the 180 kDa uncleaved spike protein, and S cleaved denotes the 90 kDa cleaved S1 and S2 subunits.