The validation of Haemagglutinin Inhibition test for the detection of antibodies against canine influenza virus in a guinea pig serum model

Haemagglutination inhibition (HI) assay is a useful method for detecting antibodies against haemagglutinating viruses such as the influenza virus. An interaction between the influenza surface protein, haemagglutinin (HA) and the receptors on the surface of erythrocytes can result in agglutination when sufficient viral particles are present. Influenza positive serum can inhibit the haemagglutinin activity whereas negative serum will have no effect. In this study, known positive canine influenza (H3N2) serum from guinea pigs was evaluated by four different factors of HI assay. The four different factors in HI assay included a) elimination of non-specific inhibitors (20% kaolin or receptor destroying enzyme (RDE)), b) type of red blood cells (RBCs), c) percentage of RBCs, and d) haemagglutination unit (HAU) of virus. Our results showed that the receptor destroying enzyme (RDE) treated serum with 1% turkey RBCs and incubation with 4HAU/25μl of virus provided highest HI value (no statistic significant among groups). In conclusion, the HI protocol for testing canine influenza virus specific antibodies in guinea pig serum model has been validated and can be used for influenza research in the future.