Are endogenous feline leukemia viruses really endogenous?

Stewart, H., Jarrett, O., Hosie, M.J. and Willett, B.J. (2011) Are endogenous feline leukemia viruses really endogenous? Veterinary Immunology and Immunopathology, 143(3-4), pp. 325-331. (doi: 10.1016/j.vetimm.2011.06.011)

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Full length endogenous feline leukemia virus (FeLV) proviruses exist within the genomes of many breeds of domestic cat raising the possibility that they may also exist in a transmissible exogenous form. Such viruses would share receptor usage with the recombinant FeLV-B subgroup, a viral subgroup that arises in vivo by recombination between exogenous subgroup A virus (FeLV-A) and endogenous FeLV. Accordingly, all isolates of FeLV-B made to date have contained a "helper" FeLV-A, consistent with their recombinatorial origin. In order to assess whether endogenous viruses are transmitted between cats, we examined primary isolates of FeLV for which the viral subgroup had been determined for the presence of a subgroup B virus that lacked an FeLV-A. Here we describe the identification of two primary field isolates of FeLV (2518 and 4314) that appeared to contain subgroup B virus only by classical interference assays, raising the possibility of between-host transmission of endogenous FeLV. Sequencing of the env gene and U3 region of the 3' long terminal repeat (LTR) confirmed that both viral genomes contained endogenous viral env genes. However the viral 3' LTRs appeared exogenous in origin with a putative 3' recombination breakpoint residing at the 3' end of the env gene. Further, the FeLV-2518 virions also co-packaged a truncated FeLV-A genome containing a defective env gene, termed FeLV-2518(A) whilst no helper subgroup A viral genome was detected in virions of FeLV-4314. The acquisition of an exogenous LTR by the endogenous FeLV in 4314 may have allowed a recombinant FeLV variant to outgrow an exogenous FeLV-A virus that was presumably present during first infection. Given time, a similar evolution may also occur within the 2518 isolate. The data suggest that endogenous FeLVs may be mobilised by acquisition of exogenous LTRs yielding novel viruses that type biologically as FeLV-B.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Hosie, Professor Margaret and Willett, Professor Brian
Authors: Stewart, H., Jarrett, O., Hosie, M.J., and Willett, B.J.
Subjects:Q Science > QR Microbiology > QR355 Virology
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation > Centre for Virus Research
Journal Name:Veterinary Immunology and Immunopathology
Publisher:Elsevier B.V.
Published Online:12 June 2011
Copyright Holders:Copyright © 2011 Elsevier B.V.
First Published:First published in Veterinary Immunology and Immunopathology 143(3-4):325-331
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
363381Rational Design of a Lentiviral VaccineMargaret HosieMedical Research Council (MRC)G0300387Centre for Virus Research