Objective: To understand the molecular characteristics of subgroup J Avian Leukosis Viruses (ALV-J) isolated from chickens with clinical hemangioma, as well as to get more information for controlling the spread of ALV-J in layer chickens flocks.
Method: We amplified the full-length viral cDNA sequences of three layers isolates associated with simple hemangioma or coexisting of hemangioma and myeloid leukosis (ML) by PCR. We also obtained some partial sequences of three layer isolates related to hemangioma and one layer isolate from ML case. Then we analyzed and compared the sequences by using DNAstar software.
Results: The phylogentic analysis showed the significant differences in the complete sequences between isolates from layer hemangioma cases and from broilers, which were grouped to two branches in the phylogenetic tree. We noted a special 19bp insertion mutation in Primer Binding Site (PBS)-Leader sequences in both JS09GY3 and JS09GY6 isolates from layer chickens with hemangioma and ML, which sequence was same to Rous Associated Virus type 1 (RAV-1), Rous Associated Virus type 2 (RAV-2) and Rous sarcoma virus (strain Schmidt-Ruppin B) (RSV-SRB). In addition, different continuous sequences deletions were found in the U3 regions of NHH and JS09GY5. By motif analysis, we found some distinct motifs including c-Est-1, TCF11 and C/EBP only in the isolates from layers with hemangioma. The five isolates associated with layer hemangioma exhibited intact E element sequences but almost identical substantial deletion was found in all Chinese broiler isolates. An 11bp continuous nucleotide insertion in the E element of JS09GY3 was found.
Conclusion: Isolates from layer showing hemangioma and broilers exhibited evident difference. We found some special mutation sites in U3, DR1 and the E element showed some potential relationship with the host breeds and the tumor phenotype, which function needs to be investigated in future. The isolates from layer cases with coexisting of hemangioma and ML were the recombinants of ALV-J and other retroviruses.