A general strategy to identify mimotopes of pathological antigens using only random peptide libraries and human sera.

Abstract

A strategy to identify disease‐specific epitopes from phage‐displayed random peptide libraries using human sera is described. Peptides on phage (phagotopes) that react with antibodies present in patient sera are purified from > 10(7) different sequences by affinity selection and immunological screening of plaques. Disease‐specific phagotopes can be identified out of this pool through an ‘antigen independent’ procedure which avails itself only of patient and normal human sera. Using this strategy, we have selected antigenic mimics (mimotopes) of two different epitopes from the human hepatitis B virus envelope protein (HBsAg). We could show that a humoral response to these mimotopes is widespread in the immunized population, suggesting that the strategy identifies phagotopes that have a potential role as diagnostic reagents. Immunization of mice with the selected phagotopes elicited a strong specific response against the HBsAg. These results open new inroads into disease‐related epitope discovery and provide the potential for vaccine development without a requirement for the use of, or even information about, the aetiological agent or its antigens.

A mimotope of Pre-S2 region of surface antigen of viral hepatitis B screened by phage display

“…But in recent years, several mimotopes were identified through polyclonal antisera screening of phage displayed library [13,14,22]. It was reported that a mimotope related to S protein of HBsAg by using 2 different sera from immunized individuals and phage-displayed random peptide liberary [15]. In this paper we report a new mimotope which is related with Pre-S 2 region of M protein of HBsAg by using one patient s serum strategy.…”

Identification of hepatitis A virus mimotopes by phage display, antigenicity and immunogenicity

“…Such phagedisplayed peptides (mimotopes) do not necessarily have sequence homology with the antigen, but have sufficient conformational homology to induce high affinity antibodies that bind to both the mimotope and the natural antigen (Collins, 1997). This approach has previously been used to identify mimotopes of hepatitis B and hepatitis C virus (Folgori et al, 1994;Prezzi et al, 1996) but not HAV, although antibody-phage libraries have been used to obtain monoclonal antibodies against HAV (Wan et al, 1998 andScholfield et al, 2002). In the work described here, the application of a phage-peptide library for cloning and identifying peptides that resemble the antigenic structure of HAV epitopes has been exploited for the first time.…”

“…This is the only mimotope that displays partial homology with both VP1 and VP3 proteins. It has homology with the SXSV motif of VP3 (69-72), and with the SVT motif of VP1 (Burrit et al, 1996;Folgori et al, 1994). A synthetic peptide VP1 (11-25), including this SVT motif, induced anti-HAV neutralizing antibodies (Emini et al, 1985) but was not useful for immunodiagnosis of acute hepatitis A (Gómara, 2000).…”

“…The methodology followed to identify HAV mimotopes using polyclonal sera is essentially similar to that described by Folgori et al (1994) …”

“…The strategy to identify peptides that mimic disease-specific epitopes from phage-displayed random peptide libraries using human sera was previously established for the identification of mimotopes of hepatitis B virus (Folgori et al, 1994) and hepatitis C virus (Prezzi et al, 1996). In the case of HAV, the phage-display technique has only been used to clone monoclonal antibodies from phage-displayed antibody libraries (Wan et al, 1998 andScholfield et al, 2002).…”