The development of hydropericardium syndrome vaccines

Hydropericardium syndrome (HPS) is a fatal disease of broiler chickens causing high mortality and heavy economic losses in various countries. More than 100 million birds have been affected by this destructive disease in less than two years worldwide. As it is a viral disease, the only solution is to vaccinate chickens. Different types of vaccines are being used against this disease in different areas of the world. Liver organ inactivated vaccines are more extensively used to control the disease initially. These vaccines have many drawbacks regarding their dose, un-predictable immune response and secondary bacterial infections. Following this, oil adjuvant vaccine was used to control the disease, however the handling stress and the formation of granuloma at the site of injection remains a problem. Consequently there is a need for cell culture adapted and attenuated vaccines, which can be administered through oral routes. A chicken embryo-adapted inactivated vaccine has shown good results but requires a continuous supply of specific, pathogen-free chicken embryos and a continuous life killing process. The continuous cell lines are a more promising solution for the production of cell culture-adapted and attenuated vaccines, which are safer, more economical and easy to administer. The following review discusses the development of modern HPS vaccines.