Neutralization of RNA-phage infectivity by anti-fr MAb and CDR-peptides that determine its specificity

RNA-bacteriophages are a highly conserved group of the simplest single-stranded viruses of defined structure. In spite of this, less is known about the antigenic and immunogenic properties of the phage particles. A knowledge of spatial structure of the bacteriophage fr as well as the very simple arrangement of phage neutralization test stimulates our interest to understand molecular details of the nature of virus neutralization and antibody-antigen recognition process. This communication reports on the construction and characterization of a mouse hybridoma FR52 secreting neutralizing MAb specific for RNA-phages fr, MS2 and GA Using the cDNA-PCR technique, we have cloned and then sequenced the genes encoding the variable domains of the MAb FR52 heavy and light chains. The CDR principles were chemically synthesized and were tested for their ability to neutralize the activity of RNA-phages fr, MS2 and GA The CDR-derived peptides H2, L2 and L3 interacted with the fr phage particles and neutralized fr phage activity. Two of these peptides - H2 and L3 - also had the ability to neutralize partly the activity of related bacteriophage MS2, but L1 and especially L3 neutralize the activity of the RNA-phage GA These results raise the possibility that simple CDR-peptides may serve as a new class of antiviral molecules.