IgG-mediated viral clearance in experimental infection with herpes simplex virus type 1: Role for neutralization and Fc-dependent functions but not C' cytolysis and C5 chemotaxis

For determination of whether the Fc moiety is required for antibody effectiveness in models of herpes simplex virus type 1 (HSV-1) infection, the effects of immune IgG and F(ab')₂ fragments were compared by using a passive transfer model of footpad infection. In the IgG- and F(ab')₂-treated groups illness developed in 2 (10%) of 20 and 6 (25%) of 24 mice, respectively, compared with 10 (63%) of 16 controls. IgG treatment markedly, and F(ab')₂ treatment moderately, reduced footpad viral titer and viral spread to sciatic nerve and spinal cord. The marked viral clearance by IgG was not attributable to C'-dependent lysis because rapid viral clearance was observed in C5-deficient B10.D2/oSn mice. Viral latency as a consequence of acute infection occurred in 38 (63%) of 60 lumbosacral dorsal root ganglia in the control group, 5 (8%; P < .001) of 60 in the IgG-treated group, and 26 (33%; P < .01) of 78 in the F(ab')₂-treated group.