ARS | Publication request: EVOLUTION OF ALV-J STRAINS

Submitted to: International Symposium On Alv J
Publication Type: Proceedings
Publication Acceptance Date: June 5, 2000
Publication Date: N/A

Technical Abstract: We designed a set of PCR primers that amplified a 2.4 kb fragment that encompasses gp85, gp37, the E element and most of the 3' LTR from the proviral DNA of nine U.S. field isolates. The PCR amplification was specific for ALV-J. The amplified fragments were cloned and sequenced. A second set of primers (6-0) was used to amplify a 1.6 kb fragment from uninfected ev- chicken embryo fibroblasts (Line 0). DNA sequencing demonstrated that the 1.6 kb fragment from Line 0 was 97.5% identical to the gp85 of HPRS-103. A distinct pattern emerged when the gp85 and gp37 amino acids of each ALV-J were aligned. The U.S. field isolates were found to be closely related to each other and somewhat more distantly related to the original HPRS-103. Furthermore, the pattern of amino acid substitutions in the U.S. field isolates suggests that the U.S. strains have been in the process of mutating and diverging from the endogenous Line 0 sequences and the oldest known ALV-J isolate. This continual mutation and evolution of U.S. strains may seriously compromise the development of effective vaccines and diagnostic tests.