Immunoglobin IgG3 as a marker for protecting against infectious viral diseases, and the uses of the same

Abstract

The invention relates to a novel variant of isolated and/or purified immunoglobulin IgG3 which can be used as a marker for protecting against infectious viral diseases such as AIDS, as a diagnostic tool, or as a preventative and curative medicament. The invention also relates to corresponding in vitro diagnostic methods.

1 . A method for the diagnosis of a pathology selected from viral infections and infectious diseases of variable development, comprising the steps of:
 (i) contacting a sample of body fluid and/or body tissue from a patient in which the presence of said pathology is suspected, with an immunoglobulin of class IgG3 having the following characteristics:   a life span in the serum of the patient of at least one month; and   a heavy chain, the molecular weight of which, determined by electrophoretic mobility, is less than the molecular weight of the IgG3s normally present in human serum (60 kDa), said heavy chain having a molecular weight of about 50 kDa and comprising the complement binding site, or one of the fragments thereof, or an antiserum comprising the immunoglobulin; and   (ii) detecting the presence of an immune complex between said immunoglobulin and a specific epitope of said pathology.   
   
   
       2 . A method for the diagnosis of the human acquired immune deficiency syndrome (AIDS), comprising the steps of:
 (i) contacting a sample of body fluid and/or body tissue, from a patient in which the presence of HIV is suspected, with an immunoglobulin of class IgG3, or a fragment thereof, having the following characteristics:   a life span in the serum of the patient of at least one month; and   a heavy chain, the molecular weight of which, determined by electrophoretic mobility, is less than the molecular weight of the IgG3s normally present in human serum (60 kDa), said heavy chain having a molecular weight of about 50 kDa and comprising the complement binding site, or one of the fragments thereof, or an antiserum comprising the immunoglobulin, or with an antiserum comprising said immunoglobulin; and   (ii) detecting the presence of an immune complex between said immunoglobulin and the R7V epitope of the gp160 protein of the HIV contained in said sample.   
   
   
       3 . A method according to  claim 2 , wherein the detecting is carried out by an immunological test selected from the group consisting of an ELISA test, RIA, a sandwich method, an immunoprecipitation and an agglutination test. 
   
   
       4 . An in vitro method for diagnosing a non-progressor patient suffering from a pathology selected from viral infections and infectious diseases of variable development, comprising obtaining a biological tissue or fluid sample from the patient and detecting the presence of immunoglobulin IgG3, said immunoglobulin IgG3 having the following characteristics:
 a life span in the serum of the patient of at least one month; and   a heavy chain, the molecular weight of which, determined by electrophoretic mobility, is less than the molecular weight of the IgG3s normally present in human serum (60 kDa), said heavy chain having a molecular weight of about 50 kDa and comprising the complement binding site.   
   
   
       5 . A method according to  claim 4 , wherein said viral infection is AIDS.