Production of Protective Human Antipneumococcal Antibodies by Transgenic Mice with Human Immunoglobulin Loci

Abstract

Infections with Streptococcus pneumoniae remain a significant cause of morbidity and mortality. To gain insight into structure-function relationships for human antibodies to pneumococcal capsular polysaccharide (PPS), we studied the response of transgenic mice reconstituted with human immunoglobulin loci, XenoMouse, to PPS antigens in a pneumococcal vaccine. Enzyme-linked immunosorbent assays of sera from mice vaccinated with a 23-valent pneumococcal vaccine revealed that they produced serotype-specific human antibodies, with the greatest response being to the PPS of serotype 3 (PPS 3). Molecular sequence analysis of three monoclonal antibodies (MAbs) to PPS 3 generated from lymphoid cells from mice vaccinated with a 23-valent pneumococcal vaccine or a PPS 3-bovine serum albumin conjugate revealed that they all used heavy-chain immunoglobulin genes from the V H 3 family, two expressed light chain genes from the human V1 family, and one expressed a mouse light chain. The protective efficacy of the two MAbs was examined in mice. A 10-g dose of both, and a 1-g dose of one, significantly prolonged survival from a lethal serotype 3 infection in CBA/N mice. Our data show that XenoMouse mice produced protective, serotype-specific human antibodies to PPS 3, and they lend support to the proposal that these animals represent a useful model to study the human antibody response to PPS antigens.Available pneumococcal vaccines consist of the purified capsular polysaccharides (PPS) of the most common serotypes of Streptococcus pneumoniae that cause disease in adults and children. Though immunogenic in normal individuals, PPS-based vaccines are poorly immunogenic in adult patients who are at increased risk for pneumococcal infections (reviewed in reference 33). Our group and others have shown that human antibodies to PPS are derived from restricted B-cell subsets which express V H 3 gene family segments (3,27,40). However, these studies were based largely on studies of polyclonal serum antibodies. Characterization of the molecular genetic structure of antibodies to the capsular polysaccharide of Haemophilus influenzae type b (4, 28) has provided insight into possible mechanisms of disease susceptibility and vaccine failure in patients with decreased expression of the genetic elements used in the response (16). This is relevant to S. pneumoniae, because overall (8) and serotype-specific V H 3 expression is decreased in human immunodeficiency virus-infected individuals (3), a group with reduced responses to pneumococcal vaccines (reviewed in reference 33) and increased susceptibility to pneumococcal infection (23).To date, the genetic makeup of a limited number of human monoclonal antibodies (MAbs) to a limited number of PPS serotypes generated by Epstein-Barr virus transformation of lymphocytes from vaccinated recipients has been described, namely, two MAbs to PPS 3 derived from different individuals (39), one to PPS 8 (46) and one to PPS 6B (40). Epstein-Barr virus transformation is difficult and unpredictable. In addition, all...

Immune Response to Pneumococcal Polysaccharides 4 and 14 in Elderly and Young Adults: Analysis of the Variable Heavy Chain Repertoire

“…Initial studies examining the structure-function relationship of antipneumococcal antibodies have provided valuable information concerning the human immune response to PPS (3,19,20,37,(48)(49)(50). These studies have been performed with human monoclonal antibodies (3,37,48), combinatorial libraries (20,49,50), and monoclonal antibodies derived from a transgenic mouse strain reconstituted with human immunoglobulin loci (7,35). However, these studies were not designed to investigate the in vivo antibody repertoire to PPS in all responders or in the elderly population.…”

Immunogenicity and Efficacy ofCryptococcus neoformansCapsular Polysaccharide Glucuronoxylomannan Peptide Mimotope-Protein Conjugates in Human Immunoglobulin Transgenic Mice

“…Mouse mice for study of the human antibody response to microbial pathogens (15,31,62) and in the area of vaccine development. CpG was used as an adjuvant with Alhydrogel the P13 conjugates in this study.…”

New Concepts in Antibody-Mediated Immunity

“…An early example of the unique insights that can come from studies with defined MAbs was the demonstration that the passive administration of a murine IgG1 MAb reliably protected mice against C. neoformans, despite the fact that consistent protection could not be demonstrated with immune sera (29). Passive protection experiments have revealed the existence of protective and nonprotective MAbs against a variety of pathogens, for which Ab efficacy is a function of the Ab isotype, specificity, or both, including C. neoformans (49,61,63), C. albicans (40), Streptococcus pneumoniae (18,71), and Mycobacterium tuberculosis (83). For C. neoformans, MAbs have been described that are protective in some hosts and that enhance disease in others (97).…”