ISOLATION AND MOLECULAR DETECTION OF MAREX DISEASE VIRUS FROM CLINICALLY SICK CHICKENS IN SELECTED AREAS OF OROMIA SPECIAL ZONE AROUND FINFINE, OROMIA REGION: ETHIOPIA.

Abstract

Marek's Disease Virus (MDV) is highly contagious, cell-associated, oncogenic herpesvirus that causes lymphoproliferative and neuropathic illness in domestic bird. In Ethiopia, it has been reported to be a potential threat to both local and exotic breeds in the backyard and commercial farming systems. A cross-sectional observational study was conducted to isolate and molecular detection of MDV from clinically sick chicken circulating in Oromia special zone around finfine from September 2021 to April 2022. The study employed outbreak investigation of poultry farms in these selected areas (Sululta, Chancho, Lega Dadi, Leg-aTafo, Sandaf, Dukam, Akaki, Sebeta, Burayu, And Holota). In total, 47 poultry farms were seen in 10 different towns, and 10 outbreaks were identified in six of those towns. A total of 31 chickens were sampled, and it was discovered that 24 of them (or 77.42%) acquired paralysis of the leg, while 26 (or 83.87%) also developed chicken rough and increased feather follicles, and all of the sick birds were exhibited additional complex clinical indications. Based on internal organ lesions from a total of 31sample (13 feather follicles, 10 spleens, and 8 livers) were inoculated on to confluent monolayer of CEF cells and incubated at 37°C in a humid incubator containing 5% CO2. After 3-7 days development of characteristic CPE for MDV were developed in 18(58.07%) sample (9 feather follicle (69.23%), 6 spleen (60%) and 3 liver 37.5%). All the isolates that were grown and developed CPEs show visible small plaques on CEF cell cultures starting from the 3rd day of the 3rd blind passage. From a total of 31 extracted DNA 25(80.65) of pooled sample tissue, PCR results revealed the presence of a 318 bp fragment of the MDV ICP4 gene. Thus, from 10 Spleen, 8 (or 80% of them), 13 Feather follicles11 (or 84.62%), and 8 Liver (or 75% of them) were confirmed as the MDV's causes. Therefore, from 10 Spleen, 8 (80%), 13 Feather follicles11 (84.62%), and 8 Liver (75%) were confirmed as MDV infected. As a result, the current study showed that Marek's disease (MD) occurrence, clinical and pathological symptoms, and severity of mortality were observed beyond the reach of immunization. Therefore, it was advised that further research be done on the molecular characterization and genomic type of the Marek's disease virus throughout the entire nation.