Preparation and evaluation of chicken embryo-adapted fowl adenovirus serotype 4 vaccine in broiler chickens

Abstract

The current study was planned to develop an efficient vaccine against hydropericardium syndrome virus (HSV). Currently, formalin-inactivated liver organ vaccines failed to protect the Pakistan broiler industry from this destructive disease of economic importance. A field isolate of the pathogenic hydropericardium syndrome virus was adapted to chicken embryos after four blind passages. The chicken embryo-adapted virus was further serially passaged (12 times) to get complete attenuation. Groups of broiler chickens free from maternal antibodies against HSV at the age of 14 days were immunized either with 16th passage attenuated HSV vaccine or commercially formalized liver organ vaccine. The antibody response, measured by enzyme-linked immunosorbent assay was significantly higher (P < 0.05) in the group immunized with the 16th passage attenuated HSV vaccine compared to the group immunized with liver organ vaccine at 7, 14, and 21 days post-immunization. At 24 days of age, the broiler chickens in each group were challenged with 10(3.83) embryo infectious dose(50) of pathogenic HSV and were observed for 7 days post-challenge. Vaccination with the 16th passage attenuated HSV gave 94.73% protection as validated on the basis of clinical signs (5.26%), gross lesions in the liver and heart (5.26%), histopathological lesions in the liver (1.5 ± 0.20), and mortality (5.26%). The birds inoculated with liver organ vaccine showed significantly low (p < 0.05; 55%) protection estimated on the basis of clinical signs (40%), gross lesions in the liver and heart (45%), histopathological lesions in the liver (2.7 ± 0.72), and mortality (35%). Birds in the unvaccinated control group showed high morbidity (84%), mortality (70%), gross (85%), and histopathological lesions (3.79 ± 0.14) with only 10% protection. In conclusion, this newly developed HSV vaccine proved to be immunogenic and has potential for controlling HSV infections in chickens.

Preparation and Evaluation of Lyophilized Live Attenuated Vaccine of Inclusion Body Hepatitis Hydropericardium Syndrome (IBH-HPS) against Challenge in Broiler Chickens

“…This vaccine has many drawbacks, including (1) unpredictable immune response provoked by the vaccine, (2) impurity and the vaccine may contains other viruses and bacteria (Mansoor et al, 2010). The above results revealed that the lyophilized live attenuated vaccine was safer, immunogenic and easy to administer.…”

“…All the prepared vaccines were tested for sterility on different microbiological media. The stability of the vaccines was also checked before administration to birds (Mansoor et al, 2010).…”

Hydropericardium Hepatitis Syndrome Emerged in Cherry Valley Ducks in China

“…No chicks died in the KR5 strain infected group while the mortality with the field isolates was up to 100% (Mazaheri et al, 1998). Moreover, effective oil emulsion vaccines have been introduced in breeder and broiler flocks for disease prevention and control (Mansoor et al, 2011;Kim et al, 2014).…”

Pathogenicity and Cytokine Gene Expression Pattern of a Serotype 4 Fowl Adenovirus Isolate

“…HHS associated losses could be reduced by vaccination. Inactivated liver homogenates from infected chickens, and inactivated virus propagated in cell culture and/or embryonated eggs based vaccines are available, however they provide only variable protection [6,25]. Recently, Schonewille et al (2010) reported live FAdV-4 vaccine, but with lack of neutralizing antibodies.…”