Mycobacterial heat‐shock proteins as carrier molecules

Abstract

We have previously shown that the priming of mice with live Mycobacterium tuberculosis var. bovis (Bacillus Calmette-Guérin, BCG) and immunization with the repetitive malaria synthetic peptide (NANP)40 conjugated to purified protein derivative (PPD), led to the induction of high and long-lasting titers of anti-peptide IgG antibodies, overcoming the requirement of adjuvants and the genetic restriction of the antibody response to the peptide (Lussow et al., Proc. Natl. Acad. Sci. USA 1990. 87:2960). This initial work led us to the following observations. BCG had to be live for priming to lead to the induction of anti-peptide antibodies. Surprisingly, priming with other living microorganisms which chronically infect the macrophage (e.g. Salmonella typhimurium and Leishmania major) also induced anti-peptide antibodies in mice immunized with PPD-(NANP)40 conjugate. It was, thus, hypothesized that molecules expressed during active infection and also known to be highly conserved between species, namely the heat-shock proteins (hsp), could mediate the T cell sensitization required for the production of anti-peptide antibodies. In fact, when the PPD protion of the conjugate was replaced by a highly purified recombinant protein corresponding to the 65-kDa (GroEL-type) hsp of M. bovis, this resulted in the production of anti-(NANP) IgG antibodies in BCG-primed mice, irrespective of the major histocompatibility complex-controlled responsiveness to the (NANP) sequence itself. Further, similar induction of anti-peptide antibody response was also obtained with a recombinant 70-kDa (DnaK-type) hsp of M. tuberculosis, but not with a small molecular mass (18 kDa) of M. leprae. Finally, an adjuvant-free carrier effect for anti-peptide IgG antibody production in BCG-primed mice, was also exerted by the GroEL hsp of Escherichia coli. This finding that hsp can act as carrier molecules without requiring conventional adjuvants is of potential importance in the development of vaccine strategies.

Successful primate immunization with peptides conjugated to purified protein derivative or mycobacterial heat shock proteins in the absence of adjuvants

“…These resulls extend our previous results obtained in mice [9][10][11] and clearly show that such a vaccination strategy tnay be applicable lo higher animals, and possibly man. It is also interesting to note thai in the present series of experiments monkeys always received BCG and tbe immunogen subcutaneously (rather than intraperitoneally.…”

“…Previous results from our laboratories have shown that the carrier elTect of PPD can, at least partially, be ascribed to myeobacterial heat shock proteins of 65 and 70 kD [10,11], and that previous priming with live BCG was required for the carrier effect of the hspR65, bul not (or (he carrier effect of the hspR70 [11]. To determine whether or not the same would apply to monkeys, groups of 2 4 .Vfl/m/n monkeys, primed or not primed with BCG, were immunized subculaneously with hspR65-or hspR70-(NANP)4(i conjugates in the absence of adjuvants.…”

“…The mouse immune response to (NANP)n peptides has been shown in our and other laboratories to be under strict H-2 control, with only H-2'' mice being able to recogni?e this sequence as both a B and T cell epitope [5][6][7], Several attempts have been made to overcome this MHC restriction of the imtnune response, and several carrier molecules and adjuvant systems have been tried both in animal models and in human volunteers {reviewed in [1,2,8]), Recently, we reported that the MHC restriction of ihc immune response to a (NANP)4,) peptide is overcotne and the need for conventional adjuvants is avoided, when tnice previously pritned with bacille Calmetle Gucrin (BCG, attenuated Mvcobacterium tuberculosis var. boris) are immunized with the peptide conjugated to either purified protein derivative (PPD) [9] or with (he mycobac(erial heat shock proteins (hsp) or65 kD (GroEL-type)and 70 kD (DnaK-type) [10], Interestitigly, when the 70-kD hsp was used as a carrier tnolecule, its helper effect did not require previous priming with BCG [11]. The adjuvant-free carrier elfect of hsp was strong and long-lasting and was also shown to be exerted with other synthetic peptides and with group C meningococcal oligosaccharides [I I].…”

A Comparative Study of Stress-mediated Immunological Functions with the Adjuvanticity of Alum

“…This is supported by a previous report that inhibition of another HSP (HSP90) abrogated inflammasome formation (34). It is noteworthy that there is a great deal of evidence that exogenous HSP70 acts as an adjuvant (35)(36)(37)(38), which has been marred by criticism that the HSP70 used may have been contaminated with LPS, flaggelin, or nucleotides (39). This critique cannot be applied to the present work as exogenous HSP70 has not been used, but endogenous, inducible HSP70 was up-regulated by alum.…”

Heat Shock Proteins in Mycobacterium tuberculosis: Involvement in Survival and Virulence of the Pathogen

“…They could mediate the T cell sensitization required for the production of antibodies and can be used in the development of vaccine(s) against TB (Lussow et al, 1991). Inside the host, T cells are involved in activating macrophages and controlling the mycobacterial infection.…”