Abstract
Complement-mediated lesions developed in myxovirus membranes in the presence of antibody to host antigens. Intact virions reacted with antibody to the keratosulfate-like host antigen present in the spike layer. Spike-deprived influenza virus reacted in the same way when an antiserum to the Forssman glycolipid was used. The holes in the membrane varied considerably in size, but were otherwise similar to those found in erythrocyte membranes. This immune EM method proved useful for the localization of host material in viral membranes.