Establishment of a GFP-based indicator cell line to quantitate feline foamy virus.
To quantitate infectious feline foamy virus (FeFV), Crandell feline kidney (CRFK) cells were transfected with the gfp gene under the control of the FeFV long terminal repeat (LTR) for establishing an indicator cell line named FFG cells. The FeFV activates promoter activity of the LTR to express green fluorescent protein (GFP) upon infection. The titers determined by GFP-positive FFG cells (GFP-based assay) were higher than those determined by the cytopathic effects-positive CRFK cells (CPE-based assay). The titers determined by the GFP-based assay reached a plateau at 3-4 days post infection (d.p.i.), while those by the CPE-based assay reached 6-8 d.p.i. When stock viruses of various FeFV strains were titrated by both assays, titers determined by both assays correlated well with each other. The results show that the GFP-based assay is simpler and more rapid and sensitive than the CPE-based assay. Using the GFP-based assay, we examined the in vitro host range of FeFV. It was found that FeFV can productively infect various cell lines derived from cats, dogs, chickens, a human and a bat.
Phung
Hang T T
HT
Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Tohya
Yukinobu
Y
Shimojima
Masayuki
M
Kato
Kentaro
K
Miyazawa
Takayuki
T
Akashi
Hiroomi
H
D000818:Animals; D002415:Cats; D002460:Cell Line; D003588:Cytopathogenic Effect, Viral; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics*; D016092:Spumavirus / Q000235:genetics / Q000302:isolation & purification*; D020079:Terminal Repeat Sequences; D015533:Transcriptional Activation; D014162:Transfection
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins