Molecular epidemiology of avian leukosis virus subgroup J in layer flocks in China.
Avian leukosis virus subgroup J (ALV-J) was first isolated from meat-type chickens in 1988. No field cases of ALV-J infection or tumors in layer chickens were observed worldwide until 2004. However, layer flocks in China have experienced outbreaks of this virus in recent years. The molecular epidemiology of ALV-J strains isolated from layer flocks was investigated. The env genes of 77.8% (21/27) of the ALV-J layer isolates with a high degree of genetic variation were significantly different from the env genes of the prototype strain of ALV-J (HPRS-103) and American and Chinese strains from meat-type chickens (designated ALV-J broiler isolates). A total of 205 nucleotides were deleted from the 3' untranslated region of 89.5% (17/19) of the ALV-J layer isolates. Approximately 94.7% (16/17) of the layer isolates contained a complete E element of 146 to 149 residues. The U3 sequences of 84.2% (16/19) of the ALV-J layer isolates displayed less than 92.5% sequence homology to those of the ALV-J broiler isolates, although the transcriptional regulatory elements that are typical of avian retroviruses were highly conserved. Several unique nucleotide substitutions in the env gene, the U3 region, and the E element of most of the ALV-J layer isolates were detected. These results suggested that the env gene, E element, and U3 region in the ALV-J layer isolates have evolved rapidly and were significantly different from those of the ALV-J broiler isolates. These findings will contribute to a better understanding of the pathogenic mechanism of layer tumor diseases induced by ALV-J.
Division of Avian Infectious Diseases, State [corrected] Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
Yulong
Y
Gao
Bingling
B
Yun
Liting
L
Qin
Wei
W
Pan
Yue
Y
Qu
Zaisi
Z
Liu
Yongqiang
Y
Wang
Xiaole
X
Qi
Honglei
H
Gao
Xiaomei
X
Wang
D000818:Animals; D001353:Avian Leukosis / Q000453:epidemiology* / Q000821:virology*; D001354:Avian Leukosis Virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D002645:Chickens; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D004196:Disease Outbreaks; D014644:Genetic Variation; D005838:Genotype; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009154:Mutation; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014759:Viral Envelope Proteins / Q000235:genetics
D012367:RNA, Viral; D014759:Viral Envelope Proteins