An immunoglobulin V gene polymorphism in the rat

Area of Science:

• Immunogenetics
• Molecular Immunology
• Rat Strain Analysis

Background:

• Antibodies from different rat strains exhibit distinct isoelectric focusing patterns.
• AVN rats possess unique antibody profiles compared to other strains like DA when responding to phenyloxazolone (phOx).

Purpose of the Study:

• To investigate the genetic basis of idiotype expression in anti-phOx antibodies.
• To determine the inheritance pattern of the specific idiotype (Ox-r1) found in AVN rats.

Main Methods:

• Isoelectric focusing of anti-phOx antibodies from different rat strains.
• Development of an anti-idiotype reagent to detect specific antibody idiotypes.
• Inhibition assays using various antisera to characterize idiotype binding.
• Genetic analysis of idiotype inheritance in F1 and backcross rat populations.

Main Results:

• Shared isoelectric focusing bands were observed in anti-phOx antibodies from AVN rats, but not in other strains.
• An anti-idiotype reagent specifically bound AVN rat anti-phOx antibodies.
• The idiotype (Ox-r1) was present in F1 hybrids and its inheritance in backcrosses suggested control by a single gene or closely linked genes.
• The gene(s) controlling Ox-r1 is not linked to the Ig kappa chain locus.

Conclusions:

• The expression of the Ox-r1 idiotype in AVN rats is genetically determined.
• The inheritance pattern strongly suggests a single gene or linked genes control this idiotype.
• The genetic locus for Ox-r1 is likely located on the immunoglobulin heavy (Ig H) chain V gene, not linked to the Ig kappa chain locus.