Hemagglutination Hemagglutination involves agglutination of RBCs. Viral hemagglutination inhibition tests for antibodies by the antibodies'ability to prevent viruses from agglutinating RBCs. Red blood cells Viruses Hemagglutination Figure 18.7Hemagglutination • Hemagglutination involves agglutination of RBCs. • Viral hemagglutination inhibition tests for antibodies by the antibodies' ability to prevent viruses from agglutinating RBCs. Figure 18.7