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Dominance of highly divergent feline leukemia virus A progeny variants in a cat with


Senior Member

Dominance of highly divergent feline leukemia virus A progeny variants in a cat with recurrent viremia and fatal lymphoma

A Katrin Helfer-Hungerbuehler1 email, Valentino Cattori1 email, Felicitas S Boretti2 email, Pete Ossent3 email, Paula Grest3 email, Manfred Reinacher4 email, Manfred Henrich4 email, Eva Bauer1 email, Kim Bauer-Pham1 email, Eva Niederer5 email, Edgar Holznagel1 email, Hans Lutz1 email and Regina Hofmann-Lehmann1 email

1 Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
2 Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
3 Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
4 Institute of Veterinary Pathology, University of Giessen, Giessen, Germany
5 Institute of Biomedical Engineering, University of Zurich and ETH, Zurich, Switzerland

Retrovirology 2010, 7:14doi:10.1186/1742-4690-7-14

The electronic version of this article is the complete one and can be found online at: http://www.retrovirology.com/content/7/1/14

In a cat that had ostensibly recovered from feline leukemia virus (FeLV) infection, we observed the reappearance of the virus and the development of fatal lymphoma 8.5 years after the initial experimental exposure to FeLV-A/Glasgow-1. The goals of the present study were to investigate this FeLV reoccurrence and molecularly characterize the progeny viruses.


The FeLV reoccurrence was detected by the presence of FeLV antigen and RNA in the blood and saliva. The cat was feline immunodeficiency virus positive and showed CD4+ T-cell depletion, severe leukopenia, anemia and a multicentric monoclonal B-cell lymphoma. FeLV-A, but not -B or -C, was detectable. Sequencing of the envelope gene revealed three FeLV variants that were highly divergent from the virus that was originally inoculated (89-91% identity to FeLV-A/Glasgow-1). In the long terminal repeat 31 point mutations, some previously described in cats with lymphomas, were detected. The FeLV variant tissue provirus and viral RNA loads were significantly higher than the FeLV-A/Glasgow-1 loads. Moreover, the variant loads were significantly higher in lymphoma positive compared to lymphoma negative tissues. An increase in the variant provirus blood load was observed at the time of FeLV reoccurrence.

Our results demonstrate that ostensibly recovered FeLV provirus-positive cats may act as a source of infection following FeLV reactivation. The virus variants that had largely replaced the inoculation strain had unusually heavily mutated envelopes. The mutations may have led to increased viral fitness and/or changed the mutagenic characteristics of the virus.


Senior Member
feline leukemia

do they think its possible for humans to contract it from cats or is just of note to show that contagion never ends....


Señor Mumbler
But it may serve as an indication that similar processes should be studied in XMRV. ENV mutations sound familiar!


Senior Member
As far as I know it is not a zoonosis.


J Am Vet Med Assoc. 2000 Nov 15;217(10):1475-9.

Survey of veterinary conference attendees for evidence of zoonotic infection by feline retroviruses.

Butera ST, Brown J, Callahan ME, Owen SM, Matthews AL, Weigner DD, Chapman LE, Sandstrom PA.

HIV and Retrovirology Branch, Division of AIDS, STD, and TB Laboratory Research, National Center for Infectious Diseases, Centers for Disease Control and Prevnetion, Atlanta, GA 30333, USA.

OBJECTIVE: To examine exposure risks, possibility of zoonosis, and potential disease associations for feline retroviruses among a group of occupationally exposed individuals. DESIGN: Unlinked voluntary cross-sectional epidemiologic survey. SAMPLE POPULATION: 204 veterinarians, laboratory scientists, and other occupationally exposed individuals who attended a veterinary conference on feline geriatric medicine. PROCEDURE: Blood was collected from participants who also completed a 13-question survey requesting demographic, occupational, exposure, and health information. Blood specimens were fractionated into plasma and mononuclear cell components. Plasma was tested for antibodies against feline immunodeficiency virus (FIV) and feline foamy virus (FeFV), as well as p27 antigen of FeLV. Mononuclear cell lysates were tested for FeLV provirus. RESULTS: Subjects reported extensive duration of work with cats (mean, 17.3 years) and multiple high-risk exposures (eg, cat bites, scratches, and injuries with sharp instruments) per year. However, neither serologic nor molecular evidence of zoonosis with any of the 3 feline retroviruses was detected. CONCLUSIONS AND CLINICAL RELEVANCE: Veterinarians encounter occupational exposures to animal material that place them at high risk for zoonoses. For feline retroviruses, the risk of zoonosis among healthy adult humans appears to be extremely small. However, potential for retroviral zoonosis, especially for viruses such as FeLV and FeFV that can replicate in human cells, cannot be eliminated, and universal precautions to reduce potential exposures should be used when handling sick cats.

PMID: 11128537 [PubMed - indexed for MEDLINE]