Neutralization Reactions Eliminate the harmful effect of a virus or exotoxin Red blood cells Antiviral antibodies Viruses Viruses neutralized and from serum hemagglutination inhibited (b)Viral hemagglutination test to detect antibodies to a virus.These viruses will normally cause hemagglutination when mixed with red blood cells.If antibodies to the virus are present,as shown here,they neutralize and inhibit hemagglutination. Figure 18.8b Neutralization Reactions • Eliminate the harmful effect of a virus or exotoxin Figure 18.8b