Affiliation:
1. Department of Pathology, University of California, Irvine 92717.
Abstract
The effects of recombinant human gamma interferon (rHuIFN-gamma; two identical monomers of 140 residues in length) and of two re-engineered C-terminal variants, rHuIFN-gamma Tetra-Ser (residues 129 to 132 replaced by serine) and rHuIFN-gamma 125 (two identical monomers of 125 residues each with the last 14 residues plus an additional alanine from the C terminus deleted), were compared in terms of several in vitro biological activities. By using three different human cell lines (HeLa 229, HEp-2, and A549), the interferons were tested for their ability to inhibit: (i) growth of Chlamydia trachomatis; (ii) replication of encephalomyocarditis virus; and (iii) cell growth. rHuIFN-gamma restricted the growth of chlamydiae to 50% of the non-IFN-treated control at concentrations ranging from 0.01 to 0.05 ng/ml, depending on the cell type assayed. One of the modified proteins, rHuIFN-gamma Tetra-Ser, also decreased the growth of chlamydiae, but it required a concentration of approximately 0.5 ng/ml to produce 50% inhibition. rHuIFN-gamma 125 had the lowest antichlamydial activity of the three IFN-gamma variants tested; concentrations of 1 to 20 ng/ml were needed to reduce the growth of C. trachomatis to 50% of that of the control. The relative antiviral and antiproliferative activities of the three IFN-gamma preparations paralleled their antichlamydial activities in these three cell lines. The antiencephalomyocarditis virus activities of rHuIFN-gamma Tetra-Ser and rHuIFN-gamma 125 were reduced by approximately 10-fold and 10(2)- to 10(3)-fold, respectively, compared with the antiviral activity of rHuIFN-gamma. Proliferation of the three cell lines was restricted to approximately 50% of the control with 0.5 to 10 ng of rHuIFN-gamma per ml. Inhibition of cell growth by rHuIFN-gamma Tetra-Ser was significant only at concentrations equal to or greater than 30 ng/ml, and the rHuIFN-gamma 125 variant did not significantly decrease the growth of any of the three cell lines at the concentrations tested. These results suggest that the C-terminal portion of rHuIFN-gamma is critical for maintaining the conformation necessary for inducing the antichlamydial, antiviral, and antiproliferative activities of the molecule.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
25 articles.
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