Recombinant feline leukemia virus (FeLV) variants establish a limited infection with altered cell tropism in specific-pathogen-free cats in the absence of FeLV subgroup A helper virus.
Feline leukemia virus subgroup B (FeLV-B) is commonly associated with feline lymphosarcoma and arises through recombination between endogenous retroviral elements inherited in the cat genome and corresponding regions of the envelope (env) gene from FeLV subgroup A (FeLV-A). In vivo infectivity for FeLV-B is thought to be inefficient in the absence of FeLV-A. Proposed FeLV-A helper functions include enhanced replication efficiency, immune evasion, and replication rescue for defective FeLV-B virions. In vitro analysis of the recombinant FeLV-B-like viruses (rFeLVs) employed in this study confirmed these viruses were replication competent prior to their use in an in vivo study without FeLV-A helper virus. Eight specific-pathogen-free kittens were inoculated with the rFeLVs alone. Subsequent hematology and histology results were within normal limits, however, in the absence of detectable viremia, virus expression, or significant seroconversion, rFeLV proviral DNA was detected in bone marrow tissue of 4/4 (100%) cats at 45 weeks postinoculation (pi), indicating these rFeLVs established a limited but persistent infection in the absence of FeLV-A. Altered cell tropism was also noted. Focal infection was seen in T-cell areas of the splenic follicles in 3/4 (75%) rFeLV-infected cats analyzed, while an FeLV-A-infected cat showed focal infection in B-cell areas of the splenic follicles. Nucleotide sequence analysis of the surface glycoprotein portion of the rFeLV env gene amplified from bone marrow tissue collected at 45 weeks pi showed no sequence alterations from the original rFeLV inocula.
Bechtel
M K
MK
Department of Biochemistry and Molecular Biology, School of Medicine, University of Southern California, Los Angeles 90033, USA.
Hayes
K A
KA
Mathes
L E
LE
Pandey
R
R
Stromberg
P C
PC
Roy-Burman
P
P
D000818:Animals; D000956:Antigens, Viral / Q000097:blood; D001483:Base Sequence; D002371:Cat Diseases / Q000276:immunology / Q000821:virology*; D002415:Cats; D017931:DNA Primers / Q000737:chemistry; D004279:DNA, Viral / Q000737:chemistry; D020077:Endogenous Retroviruses / Q000235:genetics* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D007150:Immunohistochemistry; D005256:Leukemia Virus, Feline / Q000235:genetics* / Q000276:immunology; D009500:Neutralization Tests / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011995:Recombination, Genetic / Q000276:immunology*; D012192:Retroviridae Infections / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D012469:Salivary Glands / Q000166:cytology; D017422:Sequence Analysis, DNA; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000166:cytology; D018523:Tropism / Q000276:immunology; D014412:Tumor Virus Infections / Q000276:immunology / Q000662:veterinary* / Q000821:virology
D000956:Antigens, Viral; D017931:DNA Primers; D004279:DNA, Viral