Unique Long Terminal Repeat and Surface Glycoprotein Gene Sequences of Feline Leukemia Virus as Determinants of Disease Outcome

Genetic Characterization of Feline Leukemia Virus from Florida Panthers

“…In FeLV-945 LTR, three 21-bp repeats form 2 junctions: 1 junction is formed by the fi rst repeat and the adjacent second repeat; the other is formed by the second and third repeats. Each junction includes a c-Myb binding site that increases the rate of viral replication through the recruitment of transcriptional coactivator binding protein (cAMP response element) (11). FeLV-Pco LTR sequences had 1 copy of the repeat junction ( 945 causes multicentric lymphoma, myeloproliferative disorder, and anemia and has never been associated with thymic lymphoma (26).…”

“…Because FeLV-945 is well characterized and highly virulent in the domestic cat (11,25), sequence elements associated with disease determination (env) and transcription enhancement (LTR) in FeLV-945 were examined in FeLV-Pco. In the envelope protein, 10 signature amino acid residues (found within the surface glycoprotein) that were shared between FeLV-Pco and FeLV-945 were distinctive from other strains of FeLV ( Figure 5).…”

“…Although the mechanism of immunopathogenesis is unclear, viral envelope proteins may be involved (9). FeLV envelope (env) and the long terminal repeat (LTR) sequences have been suggested as being involved in determination of disease sequelae, virus transactivation, and virus replication (10)(11)(12). There are 4 naturally occurring viral subgroups of exogenous FeLV (A, B, C, and T) that are distinguished genetically by sequence differences in the env gene and functionally by receptor interactions required for cell entry (13).…”

Importance of Receptor Usage, Fli1 Activation, and Mouse Strain for the Stem Cell Specificity of 10A1 Murine Leukemia Virus Leukemogenicity

“…However, other roles, such as inducing hyperproliferation in a preleukemic stage by interaction with other host cell factors, may also be important (15). Interestingly, we found that recombinants with endogenous retroviral sequences were a rare event in 10A1 infections and were only Variations in the env gene have also been implicated in the altered leukemia specificity in feline leukemia viruses, although this may involve a receptor-independent mechanism (12,14,28). Fli1: the common denominator in erythro(blastic) leukemia?…”

The Surface Glycoprotein of Feline Leukemia Virus Isolate FeLV-945 Is a Determinant of Altered Pathogenesis in the Presence or Absence of the Unique Viral Long Terminal Repeat

“…FeLV-A is weakly pathogenic in nature but is associated in unvaccinated animals with the induction of leukemia and lymphoma. Experimental infection with FeLV-A typically results in thymic lymphoma of Tcell origin after prolonged latency of one to three years (6)(7)(8).…”