Pathogenesis, molecular variability, and molecular detection of avian leukosis virus subgroup J

This research included four objectives: (1) examination of potential interactions between avian leukosis virus subgroup J (ALV-J) and very virulent Marek's disease virus (wMDV), or ALV-J and fowl adenovirus (FAV); (2) molecular characterization of the full-length proviral genome of an ALV-J-like isolate (ADOL-7501); (3) characterization of the 3′ untranslated region of 40 ALV-J-like isolates; and (4) development of a molecular-based assay for detection of ALV-J in feather pulp.; The onset of ALV-J viremia occurred earlier and the plasma content of ALV-J RNA was higher in chickens co-infected with ALV-J and wMDV. ALV-J did not induce damage to the bursa of Fabricius. wMDV was more readily isolated from blood leukocytes of dually infected chickens.; ALV-J and fowl adenovirus (FAV) did not appear to interact to induce enhanced pathology or delayed growth in young chickens.; The complete proviral genome of an oncogenic ALV-J-like isolate (ADOL-7501) was sequenced and examined phylogenetically. ADOL-7501 induced tumors detected between 24 and 56 days of age. The proviral genome of ADOL-7501 showed high identity (97%) to the prototype HPRS-103. The highest divergence was found in the env gene. ADOL-7501 does not contain rTM, does not carry an oncogene, and contains a complete E element. The long terminal repeat of ADOL-7501 contains typical retroviral transcription regulatory sequences. Anti-ADOL-He 1 antibodies did not neutralize ADOL-7501. The 3′ UTR of 39 ALV-J proviruses was sequenced and characterized. The direct repeat DR1 was present in all isolates. A complete E element was found only in proviruses from tumors. All proviruses isolated from clinically healthy chickens contained a truncated E element. The 3′ long terminal repeat (LTR) of all viruses contained typical retroviral transcription regulatory elements. The LTR repeat region R was identical in all proviruses, and the 3′U5 region was highly conserved.; A molecular-based (PCR) method for detection of ALV-J in feather pulp was developed. The sensitivity of the PCR assay was similar to that of virus isolation between 7 and 42 days of age for chickens infected as embryos. The feather pulp PCR assay is a suitable alternative method requiring minimal cost and equipment for sampling in the field.