IgY antibodies for the immunoprophylaxis and therapy of respiratory infections

Abbas, Aymn Talat; El-Kafrawy, Sherif Aly; Sohrab, Sayed Sartaj; Azhar, Esam Ibraheem Ahmed

The pathogen-specific titer of IgY typically starts to increase in eggs from the second week after immunization, peaking in the fifth week. Wen et al 43 isolated egg yolk IgY against influenza B virus after immunization of the hens with an inactivated virus. The IgY yield was 76.5 mg per yolk, with a purity of 98.2%. The specific binding of the IgY to the viral proteins was demonstrated by Western blotting and hemagglutination inhibition test. The researchers used plaque reduction assays to demonstrate the efficacy of the specific IgY in neutralizing the influenza infection in MDCK cells. In vivo studies showed that intranasal treatment of mice prior to or after influenza B virus infection with virus-specific IgY had a protective effect by reducing viral replication in the lungs. The work of Wen et al showed that IgY specific to influenza B can readily provide a good alternative for influenza B prevention and treatment. 43 Influenza-specific IgYs can be administered to humans (either intranasally or orally) and could serve as a quick and safe strategy in the fight against a pandemic influenza (Table 1) . 44 Pathogen-specific IgYs can remain in the sera and eggs of immunized hens for at least 2 months. In vitro investigation of IgYs produced from hens immunized with inactivated H1N1, H3N2, and H5N1 influenza viruses showed that the IgYs that were produced inhibited homologous as well as heterologous influenza viral strains. 44 In vivo studies in a mouse model showed that intranasal administration of H5N1-specific IgYs 1 hour prior to infection had a 100% protection against lethal challenge with H5N1. Interestingly, IgY to H5N1 was found to also protect against A/Puerto Rico/ 8/34 H1N1. 44 Another study found that intranasal administration of H5N1-specific IgYs in mice before and after lethal infection with H5N1 and H5N2 resulted in complete recover of the infection. Another interesting finding from this study was the presence of anti-H5N1 IgY antibodies in eggs bought directly from the market. 19 Another study tested the efficacy of avian IgY neutralizing antibodies against the pandemic influenza virus A/H1N1. The antibodies were derived from ostrich eggs immunized with a swine influenza virus vaccine strain. 95 The quantity of the IgY produced was very large and was found to have strong crossreactivity with pandemic influenza H1N1 and swine influenza virus as shown by ELISA and immunocytochemistry. Ostrich IgY antibodies were found to inhibit the hemaggregation activity of erythrocytes that was induced by pandemic influenza A/H1N1 virus. The IgYs generated were found to inhibit the cytopathological effects of H1N1 on MDCK cells upon cocultures with the antibodies, confirming the viral neutralization in the cells. The large amount of IgY generated from only one female ostrich makes this approach a cost-effective way to produce IgY antibodies against pandemic influenza virus A/ H1N1 (Table 1) .