In 5 days after virus infection, 24 of 30 DHAV-1-infected ducks, 25 of 30 DHAV-3-infected ducks and 24 of 30 co-infected ducks survived in the Pep1-KLH immunized group, whereas 26 of 30 DHAV-1-infected ducks, 25 of 30 DHAV-3-infected ducks, and 27 of 30 co-infected ducks died with typical symptoms of DVH in the PepN-KLH immunized group (Figure 9b). The gene discussed is ANPEP; the disease is viral infectious disease.