Enhanced immunogenicity of a sequence derived from hepatitis B virus surface antigen in a composite peptide that includes the immunostimulatory region from human interleukin 1.

Abstract

The effect on immunogenicity of coupling the immunostimulatory nonapeptide sequence (residues 163-171) from human interleukin 1f3 (IL-1if) to a small immunogen was examined. A 21-amino acid sequence spanning positions 12-32 on the large protein of hepatitis B surface antigen was chosen as a model. Three peptides were synthesized corresponding to the IL-13-derived sequence ], the hepatitis B surface antigen-derived sequence [peptide S1-(12-32)] and a composite peptide that included both these sequences separated by a spacer of two glycine residues [peptide S1-(12-32)-IL-(163-171)]. In an in vitro thymocyte proliferation assay, both peptides S1-(12-32)-IL-(163-171) and showed comparable activity, whereas peptide S1-(12-32) was inactive. Groups of five to seven mice each from C3H/CH, BALB/c, SJL/J, and C57BL/6 strains were immunized with equimolar amounts of either peptide S1-(12-32), peptide S1-(12-32)-IL-(163-171), or a mixture of peptides S1-(12-32) and IL-(163-171), and sera were screened for anti-S1-(12-32) antibodies. In all strains, peptide S1-(12-32)-IL-(163-171) elicited an increased primary and secondary anti-S1-(12-32) antibody response compared to the other two groups. Further, peptide S1-(12-32)- also induced an increased number of responders to primary immunization, though the number of responders was quantitative in all groups following secondary immunization. At least part of the enhanced immunogenicity of the S1-(12-32) sequence in peptide S1-(12-32)-IL-(163-171) appears to be due to augmented T-helper cell activity. These results suggest that coupling of the immunostimulatory IL-113derived sequence in tandem with an immunogen may confer inbuilt adjuvanticity.The cytokine interleukin 1 (IL-1) has been credited with a wide array of biological properties, which include amplification of both cellular and humoral immune responses to infectious or foreign agents (reviewed in refs. 1 and 2). Although precise details at the molecular level remain obscure, it is now widely believed that IL-1 plays an important role in T-and B-cell activation (1, 2). The immunoregulatory effects of IL-1 on T cells include enhanced proliferation in response to mitogen or antigen (3)(4)(5) and enhanced production of autocrine growth factors (3, 6). IL-1 has also been shown to act directly on B cells. It augments primary antibody responses both in vivo and in vitro (7-10) and can prime human B cells for subsequent activation (11). A B-cell growth and differentiation activity for IL-1 has also been described (12). Recently Uhl et al. (13) have identified IL-1 receptors on human monocytes, suggesting that initiation of the immune response by IL-1 can also be at the level of accessory cells.Though it has been suggested that IL-1 could serve as an adjuvant in conjunction with weakly immunogenic vaccines (14), its potent inflammatory activity (1, 2) restricts this application. Antoni et al. (15) have synthesized several short peptide fragments from hydrophilic sequences on human and murine IL-1 to determine the minima...

New Generation Vaccines

“…Moreover in the case of HBsAg, the peptide was used both mixed with antigen (Tagliabue et a1., 1989) or physically coupled to part of the antigen itself (i.e. the peptide 12-32 of HBsAg) (Rao and Nayak 1990). 1 for more details see Boraschi et aI, 1988 Given its small size, a fascinating alternative is to engineer the sequence encoding this peptide within recombinant antigens.…”

Cytokines as potential vaccine adjuvants

“…Nencioni, et al [11], identified an IL-1B peptide fragment corresponding to residues 163-171 (plL-1) which lacked the pyrogenicity of IL-1 but retained the adjuvant activity of IL-1 when used at significantly higher doses (50 mg/kg of pIL-1 were equivalent to 10 mg/kg of intact IL-1). In other studies, the intraperitoneal administration of a fusion protein consisting of piLl and hepatitis B surface antigen (HBsAg, residues 12-32) resulted in secondary antibody levels that were greater than those obtained with the administration of a mixture ofplL-1 and H BsAg [12].…”

“…It is conceivable that segments of the IL-1 protein other than plL-1 (residues 163-171) either alone or in combination could overcome these defects. Alternatively, the fusion of one or another of these fragments with the antigen may be a better strategy for reducing the dosage of the IL-1 peptide fragments needed for an adjuvant effect [12].…”

Vaccine Design

“…In fact, Rao and Nayak (1990) coupled (Table 5), and showed that the new peptide S 1-(l2-32)-IL-(163-171) could elicit a much stronger immune response than the antigen alone (Rao and Nayak, 1990). Indeed the new peptide is able to elicit an increased primary and secondary response anti-Sl-(l2-32), measurable in terms ofincreased number of responders to the primary immunization and of specific antibody titers.…”

“…The response was compared to that of mice receiving injections with control chimeric proteins containing unrelated foreign peptide sequences of the same length. A significantly higher immune response was observed in mice immunized with chimeric constructs containing the 163-171 sequence (Beckers et al, (I) Secondary response in terms of specific antibody titers (11dilution) in C3H1CH mice against SI(l2-32) peptide assessed by ELISA after immunization with peptides (Rao and Nayak, 1990). 1993), proving that the insertion of the peptide sequence increases immune response against poorly immunogenic recombinant proteins.…”