Protective Efficacy of a Locally Prepared Bivalent Duck Viral Hepatitis "Serotypes 1 and 3" Inactivated Vaccine

The spread of duck hepatitis virus (DHV) in Egypt with its' most prevalent genotypes (1 and 3) causes vast economic losses in the duck industry despite the regular vaccination with live attenuated vaccines. However, the use of live-vaccines is considered a potential risk for the non-vaccinated birds due to the viral shedding from vaccinated populations. The current study aimed to evaluate the protective efficacy and safety of two inactivated monovalent and one bivalent vaccines against DHV 1 and 3 genotypes. The inactivated monovalent (DHAV-1, DHAV-3) and bivalent (DHAV-1+3) vaccines were produced by using Montanide ISA 70 oil as an adjuvant. Three groups of 4-week-old ducklings (n=50) were vaccinated with one of the three vaccines, respectively. One group of ducklings was used as negative control (n=25). The immune-response of the vaccinated groups was measured by Virus Neutralization Test and expressed with Neutralizing Indices (NIs). The NIs for the bivalent vaccine group (5.6 and 5.4) were higher compared to the monovalent vaccine groups (5.0 and 4.7). In conclusion, the use of inactivated bivalent DHV vaccine could produce higher protective efficacy compared to the monovalent DHAV-1 and DHAV-3 vaccines.