Different quasispecies with great mutations hide in the same subgroup J field strain of avian leukosis virus

Abstract

Blood samples were collected from a local strain of chickens associated with serious tumor cases in Shandong Province. The samples were inoculated into chicken embryo fibroblast and DF-1 cells for virus isolation and identification, respectively. The inoculated cells were screened for three common chicken tumor viruses. Nine strains of avian leukosis virus subgroup J (ALV-J) were identified, and were designated LY1201-LY1209. The env gene from the LY1201 strain was amplified and cloned. All nine resultant env clones (clones 01-09) were sequenced, and the gp85 and gp37 amino acid regions were subjected to homology analysis. Clones 01 and 03 had 10 amino acid deletions in the gp85 region compared to the other seven clones, suggesting that at least two quasispecies with obvious mutations coexist in the same field strain. Among these nine clones, three had identical gp85 and gp37 sequences, and were recognized as the dominant LY1201 quasispecies. The amino acid sequence homology of gp37 and gp85 among the nine clones was 98.5%-100.0% and 96.6%-100.0% respectively, suggesting that the gp85 region of the env gene can better display the quasispecies diversity of ALV-J than gp37.

Genomic diversity of theAvian leukosis virussubgroup Jgp85gene in different organs of an infected chicken

“…In these reports, only one clone of any ALV-J isolate representing an infected bird, flock, or farm in a given period was sequenced; thus, the genomic diversity of ALV-J strains circulating in the same bird or flock was not considered. However, our laboratory detected such diversity in the gp85 gene of an ALV-J field isolate when more clones were selected for sequence comparisons [12]. …”

Synergistic pathogenic effects of co-infection of subgroup J avian leukosis virus and reticuloendotheliosis virus in broiler chickens

“…At the same time, the ALV-J infection has been very common among chicken flocks during the last 20 years in China, such as in white meat-type chickens before 2006 (Du et al, 2000;Cui et al, 2003;Zhang et al, 2004) and in layers in 2002 to 2013 (Xu et al, 2004;Guo et al, 2009;Gao et al, 2012;Cai et al, 2013). This virus continues to spread in different Chinese local breeds (Cheng et al, 2005;Cui et al, 2009;Mao et al, 2013) although eradication programmes have been initiated in some breeder farms. Previous studies have indicated that the extent of immunosuppression and pathogenicity were different among chicks with multiple as well as single viral infections.…”

Avian leukosis virus in indigenous chicken breeds, China

“…All of the viruses isolated from diseased chickens with tumors belonged to ALV-J. 8 , 9 , 10 In contrast, ALV-A, ALV-C, and viruses belonging to the new subgroup K were isolated from clinically healthy chickens. Therefore, the pathogenicity of ALV-J was relatively high among the indigenous chicken breeds.…”