Histopathological and Molecular Detection of Lymphoid Leukosis in Sonali Chickens in Chattogram, Bangladesh

Introduction: Lymphoid leukosis (LL), caused by the Avian leukosis virus (ALV), is a tumor-forming disease in poultry that causes considerable economic losses in commercial poultry farming. The present study aimed to evaluate the histopathological and molecular aspects of LL in Sonali chickens from several poultry farms in Chattogram, Bangladesh. Methods: 200 dead Sonali chickens aged from 20 to 40 weeks that showed clinical signs of the disease, including gradual weight loss, loss of appetite, enlarged abdomen, pale comb and wattle with high morbidity and low mortality, were collected from poultry farms in Patiya, Anowara, Banshkhali, Chandanaish, Mirsarai, and the Chattogram metropolitan region, Bangladesh. Necropsy of these chickens was performed systematically, and the gross lesions were documented. Samples were collected from the affected organs, including the heart, liver, spleen, and intestine, for histopathological and molecular identification of LL. Histopathological examination of those samples was performed by the routine hematoxylin and eosin (H&E) procedure. A conventional PCR targeting the ALV env gene was performed with complementary DNA (cDNA) generated from extracted RNA. Results: 120 (60%) chickens among the 200 demonstrated specific gross lesions of LL during necropsy examination, including disseminated nodular tumors in visceral organs such as the heart, liver, spleen, and intestines. Routine H&E procedure confirmed LL in 94 (78.33%) of cases. Moreover, 100 percent of the histologically confirmed samples indicated a distinct 220bp amplicon in PCR, confirming ALV infection. Conclusion: The combination of histology and molecular detection successfully revealed ALV-induced lymphoid leukosis in Sonali chickens. The presence of ALV on several farms indicated the need for stronger biosecurity measures to prevent viral spread.