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J. Virol., May 1996, 3011-3017, Vol 70, No. 5
JS Yang, RV English, JW Ritchey, MG Davidson, T Wasmoen, JK Levy, DH Gebhard, MB Tompkins and WA Tompkins
A full-length feline immunodeficiency virus NCSU1 (FIV-NCSU1) genome (JSY3)
was cloned directly from FIV-NCSU1-infected feline CD4+ lymphocyte (FCD4E)
genomic DNA and identified by PCR amplification with 5' long terminal
repeat, gag, env, and 3' long terminal repeat primer sets. Supernatant from
FCD4E cells cocultured with JSY3-transfected Crandell feline kidney (CrFK)
cells was used as an inoculum. Cell-free JSY3 virus was cytopathogenic for
FCD4E lymphocytes but did not infect CrFK cells in vitro. To determine in
vivo infectivity and pathogenesis, six young adult specific-pathogen-free
cats were inoculated with cell- free JSY3 virus. Provirus was detected at 2
weeks postinfection (p.i.) and was still detectable at 25 weeks p.i. as
determined by gag region PCR-Southern blot analysis of peripheral blood
mononuclear cell lysates. Infectious virus was recovered from peripheral
blood mononuclear cells at 6 and 25 weeks p.i., and an antibody response to
FIV was detected by 4 weeks. In the acute phase of infection, JSY3 provirus
was found only in the CD4+ lymphocyte subset; however, by 14 weeks p.i.,
the greatest provirus burden was detected in B lymphocytes. All six cats
were panlymphopenic at 2 weeks p.i., CD4+/CD8+ ratios were inverted by 6
weeks p.i., and five of the six cats developed lymphadenopathy by 10 weeks
p.i. To determine if the JSY3 molecular clone caused immunodeficiency
similar to that of the parental wild-type FIV-NCSU1, the cats were
challenged with the low-virulence ME49 strain of Toxoplasma gondii at 29
weeks p.i. Five of six cats developed clinical signs consistent with
generalized toxoplasmosis, and three of six cats developed acute
respiratory distress and required euthanasia. Histopathologic examination
of the severely affected cats revealed generalized inflammatory reactions
and the presence of T. gondii tachyzoites in multiple tissues. None of the
six age- and sex-matched specific-pathogen-free cats inoculated with only
T. gondii developed clinical disease. Our results suggest that the
pathogenesis of the molecularly cloned NCSU1 JSY3 is similar to that of
wild-type FIV-NCSU1.
Copyright © 1996, American Society for Microbiology
Molecularly cloned feline immunodeficiency virus NCSU1 JSY3 induces immunodeficiency in specific-pathogen-free cats
Department of Microbiology, Parasitology, and Pathology, College of Veterinary Medicine, North Carolina State University, Raleigh, USA.
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