CrFK feline kidney cells produce an RD114-like endogenous virus that can package murine leukemia virus-based vectors

Abstract

The feline kidney cell line CrFK is used extensively for viral infectivity assays and for study of the biology of various retroviruses and derived vectors. We demonstrate the production of an endogenous, RD114-like, infectious retrovirus from CrFK cells. This virus also is shown to efficiently package Moloney murine leukemia virus vectors.

FIG. 1

(A) Schematic representation of the Gag proteins of FeLV, RD114, and MuLV. The sizes of the precursor proteins as well as the processed end products are shown. (B) Expression of RD114-related Gag proteins in QN10S cells (lane 1), FeLV-infected FEA cells (lanes 2 and 3), MuLV Gag–Pol-transfected CrFK cells (lane 4), and CrFK cells (lane 5) in membrane extracts with antiserum directed against the RD114 CA protein, after application of protein extract from 10⁶ cells to a 7.5% sodium dodecyl sulfate-polyacrylamide gel, resolution at 40 V overnight, and transfer (2.5 mA/cm², 1 h) to a nitrocellulose (Schleicher and Schüll) membrane (8). The size of the marker protein (30 kDa) is indicated, as is the RD114 Gag protein p28 and the FeLV Gag protein p26.

FIG. 2

Western blot analysis of viral proteins in supernatants from RD114-producing FER cells (lane 1), QN10S cells infected with RD114 (lane 3), QN10S cells infected with CrLE virus (lane 4), CrFK cells (lane 5), and QN10S cells (lane 6) with antiserum directed against the RD114 CA protein. The size of p28 Gag is indicated. Lane 2 is empty.