A recombination efficiently increases the pathogenesis of the novel K subgroup of avian leukosis virus

Abstract In this study, a recombinant ALV with ALV-K env and ALV-J backbone was generated (designated ALV-K- env -J) and tested in vitro and in vivo . The growth curve in DF1 cells showed that the recombinant virus replicated more efficiently in comparison with the ALV-J and ALV-K. Although all the infected chickens showed growth retardation compared with the non-infected chickens, the viral and serological detection showed that the positive rate and virus load detected in blood and cloaca, and the positive rate and titer of antibody against p27 from the chickens infected with ALV-K- env -J were higher than those from the chickens infected with the ALV-K, but less than those from the chickens infected with the ALV-J. All these data clearly demonstrated that the recombination event in this study increased the pathogenesis of ALV-K, and the potential recombination between different ALV subgroups should be worried when the clinical co-infections occur.