Development of IL-2 Independent Feline Lymphoid Cell Lines Chronically Infected with Feline Immunodeficiency Virus: Importance for Diagnostic Reagents and Vaccines

Abstract

Two interleukin 2 (IL-2)-independent feline immunodeficiency virus (FIV) producer cell lines (FL-4 and FL-6) were produced by selecting cells from an IL-2-dependent culture of mixed peripheral blood lymphocytes infected with FIV. The new cell lines have been stable for over 1 year and spontaneously produce FIV with an average reverse transcriptase titer of 300,000 cpm/ml and an average sucrose gradient purified viral protein concentration of 1 mg/l. FIV produced from these cultures is highly infectious in vitro and in vivo. The FL-6 cell line was phenotyped as expressing the feline CD8 and Pan-T antigens, while the FL-4 cell line expressed the CD4, CD8, and Pan-T antigens. Both cell lines, however, express high levels of viral core and envelope proteins. Paraformaldehyde-inactivated whole virus and similarly inactivated whole-cell virus preparations induced a strong antibody response to core and envelope antigens in immunized cats. The establishment of FIV-producing feline IL-2-independent peripheral blood lymphocyte lines should be valuable for the development of FIV-diagnostic reagents and vaccines and also as a model for human acquired immunodeficiency syndrome vaccine development.

AIDS Vaccination Studies Using an Ex Vivo Feline Immunodeficiency Virus Model: Protection from an Intraclade Challenge Administered Systemically or Mucosally by an Attenuated Vaccine

“…The vaccine virus, FL-381, was Pet (clade A) produced by chronically infected FL4 cells that had undergone 381 passages, corresponding to Ͼ3 years, in culture. FL4 cells were established 12 years ago by Yamamoto and her group (75) and have since been distributed to many laboratories. Long-term propagation in vitro is the classic method for producing attenuated live virus vaccines, and although newer e Reciprocal of the serum dilution that gave 50% inhibition of RT production relative to virus exposed to equal dilutions of normal cat serum, as calculated by the method of Reed and Muench (63).…”

Epitope mapping of the V3 domain of feline immunodeficiency virus envelope glycoprotein by monoclonal antibodies

“…FIV-P was propagated in persistently infected CrFK cells or FL4 cells (kind gift of Dr J. Yamamoto, University of Florida, Fla., USA) as previously described (Yamamoto et al, 1988(Yamamoto et al, , 1991. Virus was concentrated from tissue culture supernatants by ultrafiltration (Minitan; Millipore) and purified by density gradient centrifugation (Montelaro et al, 1982).…”

Antiviral Activity and Conformational Features of an Octapeptide Derived from the Membrane-Proximal Ectodomain of the Feline Immunodeficiency Virus Transmembrane Glycoprotein

“…The viruses used included 11 primary isolates of subtype B (FIV-M2, -M3, -M19, -M22, -M45, -M73, -M82, -M88, -M91, -M92, and -M97) described in a previous report (10), one primary isolate of subtype A (FIV-GL8; kind gift of Os Jarrett, Glasgow, United Kingdom), and one TCA strain of subtype A (FIVPet; kindly provided by J. K. Yamamoto, Gainesville, Fla.). The viral stocks consisted of cell-free supernatant of chronically infected FL4 cells (FIV-Pet [70]) or of acutely infected MBM cells (all other viruses). Titration of the viral stocks was carried out in MBM cells and, depending on experiment design, included or did not include washout of unadsorbed virus after 5 h at 37°C to reproduce the conditions used in the FIV inhibition assay (see below).…”