Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector – Amino acid sequence disclosed in whole or in part; or...
Reexamination Certificate
1994-11-16
2001-09-25
Scheiner, Laurie (Department: 1648)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
Amino acid sequence disclosed in whole or in part; or...
C424S208100, C530S324000, C530S326000, C435S005000
Reexamination Certificate
active
06294174
ABSTRACT:
The invention relates to peptides immunologically related to proteins of a viral agents, that is to say, constituting, with regard to their immunological properties, analogues of proteins involved in a viral pathology or of antibodies formed against these proteins.
It is also concerned with the biological applications of these peptides, in particular for diagnostic, preventive and therapeutic aims.
It is known that the immunological approach is mainly used to treat or establish a diagnostic of human or animal pathologies in which infectious agents or also cellular or extra cellular constituents of the organism responsible for autoimmunity are involved.
The expression “infectious agent” as used in the description and claims, refers to viral pathogenic agents, this term covering retroviral agents or also cells infected by said agents.
This immunological approach relies upon the use of antibodies capable of recognising specifically the infectious antigen, or on the induction of immune responses of the organism, including also the auto-antibodies.
Generally, antibodies are produced by immunisation of animals against the infectious agent, previously inactivated, or against proteins purified from this agent.
However, this process is often expensive and requires the use of sophisticated techniques for the production and isolation of the infectious agents, as well as for the purification of proteins.
Furthermore, in the case of particularly virulent agents, these procedures require laboratory logistics which must follow very strict security rules, which make the procedures even more expensive.
To be useful in therapeutic, it is assumed that the antibodies must have a neutralising effect in vivo vis-a-vis the infectious agent.
However, in many pathological situations, the circulating or induced antibodies do not have such an effect on the antigenic proteins.
This problem is particularly crucial in the case of the pathologie(s) induced by the virus HIV in humans, usually called AIDS (acquired immune deficiency syndrome). The different clinical stages of the infection by HIV are indeed followed by important changes in the immune system resulting from the extreme affinity of the virus for the receptor CD4 of T4 lymphocytes, leading to the death of infected cells. Furthermore, other types of cells are infected by HIV.
It should be reminded that HIV generally refers to the retroviruses of type HIV-1 and HIV-2, isolated nowadays from the human, and the retroviruses type SIV isolated from the monkey, which are different from HIV-1 and HIV-2, as well as their numerous variants.
Studies involving the production of vaccines against HIV are mainly aimed at using viral antigens or their fragments obtained from proteins of HIV. Interest has focussed mainly on the glycoprotein of the envelope of the virus coded by the gene ENV, gp160 (gp120/41) or a fragment thereof. More recently, experimental vaccination has been approached by using internal constituents of the virus such as the proteins coded by the gene GAG (and POL).
Various animal models are used in those trials, including primates.
A certain protective effect against infection by HIV has been observed in the case of monkeys inoculated with this virus. However, these results have to be considered with caution considering the fact that these animals cannot develop AIDS.
Experimental vaccination in humans are currently on trial, mainly with the proteins or the peptides deriving from the gene ENV.
However, the efficacy of such vaccines is far from being established, and the development of a vaccine against AIDS raises numerous problems. For example, the major problem resides in the fact that in seropositive subjects, as well as in patients, most of the circulating antibodies are not capable of neutralizing the viruses and/or of eliminating the cells carrying the virus in the patients' body. Even though certain circulating antibodies are neutralising agents in vitro, their protective effect in the organism has not been efficient.
Another immunological approach consists in generating the internal image of the antigen, i.e. the anti-idiotype antibody, then to utilise this new structure as an immunisation agent, rather than the antigen itself (see (1) and (2) in the references given at the end of the description).
Such an immunisation via the internal image of the antigen requires various stages.
First of all, one has to induce immunisation with the antigen, which will allow the production of antibodies AC1, or idiotypic antibodies, directed against this antigen.
Then, one has to immunize with idiotypic antibody AC1 in order to induce anti-idiotypic antibodies AC2, which carry the internal image of the initial antigen. This internal image of the antigen corresponds to the region of binding of this antigen with the antibody AC1.
Finally, immunisation with the anti-idiotype AC2 allows the production of the anti-anti-idiotypic antibodies AC3. These antibodies AC3 are capable of reacting with the initial antigen (1, 2). Furthermore, the anti-idiotype AC2 can activate the lymphocytes which would then be able to recognise the initial antigen, as in the case of direct activation of these cells by the antigen.
The induction of anti-idiotype AC2 can also be obtained against the receptors of sensitised T cells, which are responsible for the cellular immunity. It is indeed possible to generate at the same time T lymphocytes of which the receptors are capable of recognising the foreign determinants expressed at the surface of a virus or of infected cells, and the cellular determinants of type MHC (major hystocompatibility complex). This case thus refers to sensitised lymphocytes.
During this first step, the R1 receptors of these lymphocytes express structures corresponding to the idiotype, having in fact a function similar to that of the antibody AC1.
Immunisation by thus sensitised lymphocytes (or their membrane receptor R1) then allows the production of both anti-idiotypic antibodies AC2, as well as lymphocytes with receptors R2, similar to the antibodies AC2, and directed against, or recognising, the domain of the R1 lymphocyte receptor involved in the binding to the antigen. Finally, the R2 lymphocyte receptors or the AC2 anti-idiotypic antibodies, are capable of inducing a new response of lymphocyte cells, of which the R3 receptors recognise the initial antigen (1).
This use of the internal image of the antigen is particularly interesting in influencing the mechanism of lymphocyte sensitisation. The major advantage which results therefrom resides in the fact that, recognition of the antigen by sensitised lymphocytes with the internal image does not depend upon the genetic nature of the immunised host, because the restricted control of the identity of CMH of infected target cells, or of the virus does not represent any obstacle any more to their destruction (2).
In conclusion, the antibodies directed against the anti-idiotype, being able to crossreact with the initial antigen, are capable of inducing immunity in which B lymphocytes, as well as T lymphocytes, are involved.
However, the use of antibodies or anti-idiotypic lymphocyte receptors as vectors of the internal image of the antigen in the prevention or treatment of immuno deficient diseases, is not without danger.
Indeed, one has to be particularly careful when treatments involving the injection of anti-idiotypes in the organism are used (2). For example, in the guinea pig, the presence of certain fractions of anti-idiotypic antibodies (AC2), such as the sub-class IgG2, which are capable of fixing the complement, exerts a rather suppressive effect on the production of anti-anti-idiotypic (AC3) antibodies by IgG1, which do not fix the complement, both sub-classes of IgGs being present in the same serum. Besides the inconvenience related to 2 the immuno-suppressive effect of AC2 antibodies, very weak doses of antibodies (in the order of 10 ng in the mouse) must be administered, and this subcutaneously, and not intravenously, in order to avoid immunological perturbations.
As the classical immunologi
Biquard Jean-Michel
Cosic Irena
Hearn Milton T. W.
Krsmanovic Velibor
Monash University
Nixon & Vanderhye P.C.
Parkin Jeffrey S.
Scheiner Laurie
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