MOLECULAR CHARACTERIZATION OF PAKISTANI ISOLATES OF HYDROPERICARDIUM SYNDROME AND PRODUCTION OF ITS VACCINE

Hydropericardium syndrome (HPS), a disease of chickens, has drastically affected the poultry industry in Pakistan and needs an effective therapeutic approach like vaccination. Understanding of the causative agent is essential for such an approach. Various characteristic features of the causative agent and its molecular characterizations was carried out during the present investigation.\ud \ud The passage has been made in susceptible chickens and the isolates collected during successive periods (1990-2003) were used. These isolates were characterized by experimental serological tests (agar gel precipitation, serum neutralization and indirect hemagglutination), propagation in various systems (chicken LD 50, intravenous pathogenicity index-and intracerebal pathogenicity index) and preparation of live (freeze-dried) and in-activated (using formalin and oil emulsion) vaccine was accomplished and documented by standard microbiological routine tests like sterility, potency and sensitivity tests. Finally, extraction of DNA form selected HPS isolates along with polymerase chain reaction (PCR), Restriction Fragment Length Polymorphism (RFLP), followed by agarose gel electrophoresis were carried out. There no differences in size of all the PCR products for H3 /H4 primer pair (approximately 1319 bp), which is characteristic of group 1 avian adenovirus. Restriction fragment length polymorphism of these PCR products by HPA restriction enzyme digestion yielded five bands approximately 0.15,0.2,0.25,0.3 and 0.5 Kbp. These profiles are identical to those of avian adenovirus isolates reported from India, Germany, Japan and Chile. Detection of small amount of DNA enabled the viral DNA to amplified directly from field isolates and avoid and avoid an extra seep to grow the virus in cell culture and the laborious work in serology. The present findings document that these Pakistani isolates belong to Avian adenovirus group I serotypes 4 (FAV4)