Hypervariability in the envelope genes of subgroup J avian leukosis viruses obtained from different farms in the United States

Virology. 2000 Jun 20;272(1):106-11. doi: 10.1006/viro.2000.0352.

Abstract

Avian leukosis virus, subgroup J (ALV-J), has a wide host range, preferentially infecting meat-type birds, and produces a high incidence of myelocytomatosis and nephromas. Using the published sequences from HPRS-103 (ALV-J isolated in 1989 in Great Britain), we designed a set of PCR primers that amplified proviral DNA from nine U.S. field samples. The primers were specific for ALV-J, not amplifying DNA from uninfected cells or cells infected with ALV subgroups A-E. These primers expanded a 2.4-kb fragment that encompasses gp85, gp37, the E element, and most of the 3' LTR. We also developed a set of PCR primers that amplified a 2.1-kb fragment from ALV-J-infected cells and a 1.6-kb fragment from uninfected ev- chicken embryo fibroblasts (Line 0). Upon cloning and DNA sequencing, we determined that the 2.1- and 1.6-kb fragments contained ALV-J gp85- and gp37-like sequences. Comparison of the amino acid sequences demonstrated that the Line 0 sequences were 97.5% identical with the gp85 and gp37 of HPRS-103 and somewhat less identical with the other nine U.S. isolates. This suggests that the envelope genes of ALV-J may have arisen as a result of a recombination event between exogenous ALV and Line 0-like sequences in the chicken. Phylogenetic analysis also showed that the U.S. field isolates were closely related to one another and more distantly related to the European HPRS-103. The pattern of mutations in the U.S. field isolates suggests that the U.S. strains are slowly drifting away from their progenitor Line 0-like sequences. The development of effective vaccines and diagnostic tests is likely to become more problematic as the viruses continue to mutate.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Domestic / virology*
  • Avian Leukosis Virus / chemistry
  • Avian Leukosis Virus / classification*
  • Avian Leukosis Virus / genetics*
  • Cell Line
  • Chick Embryo
  • Chickens / virology
  • Cloning, Molecular
  • DNA Primers / genetics
  • Fibroblasts / cytology
  • Fibroblasts / virology
  • Gene Products, env / chemistry
  • Gene Products, env / genetics*
  • Genes, Viral / genetics*
  • Genetic Variation / genetics*
  • Molecular Sequence Data
  • Mutation / genetics
  • Phylogeny
  • Polymerase Chain Reaction
  • Recombination, Genetic / genetics
  • Sequence Alignment
  • United States

Substances

  • DNA Primers
  • Gene Products, env

Associated data

  • GENBANK/AF247384
  • GENBANK/AF247385
  • GENBANK/AF247386
  • GENBANK/AF247387
  • GENBANK/AF247388
  • GENBANK/AF247389
  • GENBANK/AF247390
  • GENBANK/AF247391
  • GENBANK/AF247392
  • GENBANK/AF247566