acase@tulane.edu / The humoral arm of the adaptive immune system involves the production of antibodies by cells of the B cell lineage, which bind and in some cases neutralize or enhance infectivity of pathogens, including viruses. Humoral immune responses to each of the Lassa virus (LASV) structural proteins have been detected[1, 2]. However, there have been few efforts to perform fine structure epitope mapping of the antigenic sites recognized by LASV-specific antibodies. Murine monoclonal antibodies (MAbs) have been produced against several arenaviruses [1-4]. Some MAbs to Lassa virus proteins react broadly with arenaviruses demonstrating there may be an epitope or epitopes conserved among arenaviruses. Neutralizing antibody epitopes of LASV recognized by humans remains essentially unexplored. Therefore, my project will focus on identifying, characterizing and better understanding the antigen-antibody binding relationship of LASV structural proteins. We hypothesize that humans exposed to LASV differ quantitatively and qualitatively in their ability to produce antibodies that recognize potential binding epitopes on LASV proteins, and these differences can be explored via the identification and characterization of these epitopes using LASV recombinant proteins and synthetic peptides. We expect that a panel of unique human MAbs that bind specifically to LASV and LASV recombinant proteins will be isolated and prove to be valuable tools in characterizing the humoral response to LASV. The human MAbs must be characterized to determine how binding occurs. A fundamental understanding of mechanisms of antibody binding of LASV may have significant implications for the generation of antibody-based therapeutics / 1 / Rachael Yenni

It was proposed that some O-alkyl analogues of the beta-adrenergic agonist clenbuterol would be effective structural and functional congeners of clenbuterol which may then be used for the production of clenbuterol-specific idiotypic antibodies. These antibodies could possibly then be used to generate anti-idiotypic antibodies that mimic the energy-repartitioning effects of clenbuterol. Therefore, the aim of this work was to synthesise and characterise these compounds, evaluate their physiological effects, characterise the specificity of antibodies produced in response to protein conjugates of two of the novel compounds, and then use this data to determine the utility of these compounds for the generation of anti-idiotype antibodies which mimic clenbuterol. The target compounds were synthesised in five steps from 3,5-dichloro-4-hydroxyacetophenone in overall yields of 5-28%. A synthetic scheme similar to that which has led to clenbuterol was used to form the phenylethanolamine backbone, with modifications to include the O-alkyl moiety via a modified Williamson ether synthesis, and elimination of a synthetic chlorination step. Overall, 15 new compounds were synthesised, which were characterised and their structure confirmed from proton and carbon-13 NMR, IR and mass spectral data. The two haptenic analogues were then conjugated to carrier proteins using carbodiimide-based chemistries. In conclusion, the results indicated that the O-alkyl analogues, although structurally similar, were ineffective functional mimics of clenbuterol. Therefore, the anti-clenbuterol antobodies produced from the novel O-alkyl analogues would appear to be unsuitable for production of anti-idiotypic antibodies that mimic the energy-repartitioning effects of clenbuterol since the antibodies were unable to distinguish between the compound which demonstrated energy-repartitioning effects (clenbuterol) and those that did not (O-alkyl clenbuterol analogues). / Doctor of Philosophy (PhD)

Monoclonal antibodies and antibody-based entities are a major class of therapeutic proteins. The surge in development of monoclonal antibodies is predominantly due to the utilization of technologies for producing fully human antibodies, namely phage display and transgenic mice with human humoral immune systems. Human CD48, a cell-surface adhesion molecule, is a potential tumor target for the treatment of white blood cell malignancies, principally leukemia and lymphoma. A truncated, secreted form of CD48 was expressed in CHO cells, and was shown to bind to existing anti- CD48 murine antibodies. A human anti-CD48 scFv antibody fragment, (designated scFv-N2A) was previously isolated using phage display technology from a synthetic human scFv immunoglobulin gene library. The scFv-N2A was reassembled as a human IgG1 monoclonal antibody (designated IgG1-N2A), expressed in CHO cells and the binding of IgG1-N2A to recombinant CD48 was confirmed by enzyme-linked immunosorbent assay, surface plasmon resonance and fluorescence activated cell sorting. IgG1-N2A binding to CD48 on Raji cells showed that the specificity of the human antibody for GPI-linked CD48 was conserved. In biological studies using a human lymphoma cell line (Raji), it was found that the IgG1-N2A antibody was able to induce potent growth inhibition, with a 68% reduction in viable cells. Furthermore, Raji cells treated with IgG1-N2A showed evidence of increased ethidium bromide uptake and cell shrinkage, which are characteristics associated with direct induction of apoptosis. The data suggests the novel human anti-CD48 IgG1-N2A monoclonal antibody can block proliferation and promote apoptosis of lymphoma cells, and therefore has potential as a lead antibody candidate for the treatment of white blood cell malignancies.

Monoclonal antibodies were developed against pathogenic vibrios for use in rapid identification in disease situations of humans, fish and shellfish. Of the 12 fusions performed using V. alginolyticus, V. anguillarum, V. carchariae, V. cholerae, V. damsela, V. furnissii, V. harveyi, V. ordalii, V. parahaemolyticus and V. vulnificus, a total of 102 hybridomas were obtained. Based on cross-reactivity of a wide range of Vibrio strains and other gram-negative bacteria, three broad types of monoclonal antibodies were found. The three categories were: (1) ones that were species-specific or specific to a particular surface antigen, (2) a large number that reacted with several Vibrio species, and (3) three that reacted with most Vibrio strains but no other gram-negative bacteria. Each species-specific monoclonal antibody only recognized its corresponding Vibrio species and was used for identifying unknown species, confirming diagnosis of clinical isolates. In addition, several monoclonal antibodies only cross-reacted with similar Vibrio species, e.g. V. parahaemolyticus and V. alginolyticus which share a common H-antigen. Monoclonal antibodies reacting with several Vibrio species were not of particular use in diagnostic situations. Three monoclonal antibodies of the last group did not react with other genera of the family Vibrionaceae, namely Aeromonas, Photobacterium and Plesiomonas nor a wide range of gram-negative enteric bacteria. These data indicated the existence of an antigenic surface determinant common to Vibrio species. One monoclonal reacted with the heat-stable antigenic determinants on the cell surface as v as lipopolysaccharide extracted from all the vibrios studied, thus making it useful for large- scale screening of acute infections of vibrios. In a blind test, seven Vibrio species, isolated from 6 marine and a freshwater source were identified by two laboratories using phenetic tests. Results of immunotyping using monoclonals, three of seven were diagnosed as the same species, another three were designated as Vibrio species but could not be classified further due to the library not having the corresponding monoclonal, and one was diagnostically questionable. Two further tests were carried out. An unknown Vibrio formalin-fixed isolated from diseased marine animal was identified as V. parahaemolyticus by ELISA and FITC. Clinical human isolates of V. alginolyticus, V. parahaemolyticus and V. vulnificus were confirmed by monoclonals. Australian isolates of V. anguillarum appeared to be mostly of serotype O1. monoclonals raised to V. anguillarum AFHRL 1 reacted with only serotype O1 from Denmark but also most Australian isolates. All vibrios pathogenic to fish and shellfish, i.e. V. anguillarum, V. ordalii, V. alginolyticus, V. carchariae, V. cholerae, V. damsela, V. harveyi, V. parahaemolyticus and V. vulnificus, were used for attachment studies to fish cells using phase contrast and FITC-immunofluorescence microscopy. Of these vibrios, V. anguillarum, V. ordalii and V. perahaemolyticus, were found to adhere to different cells and tissues of rainbow trout while others did not appear to attach. However, attachment was inhibited by monoclonal antibodies specific to only these three vibrios. Lipopolysaccharide is well known as being a contributing factor in pathogenicity of gram-negative bacteria. PAGE electrophoresis of extracted LPS from 9 strains covering 6 Vibrio species showed the presence of a common 15,000 D fragment. This fragment was verified by immunoblotting with a genus-specific monoclonal antibody (i.e. F11P411F) recognizing nearly all vibrios. The common LPS fragment was separated and used to raise polyclonal antisera in mouse which reacted strongly with LPS itself, live as well as sodium azide-killed vibrios, but not with other gram-negative bacteria. This raised the possibility of developing vaccine from Vibrio LPS. Monoclonal antibodies developed in the present study enabled rapid identification of a number of pathogenic Vibrio species. There is still further work to produce monoclonal antibodies against additional vibrios that are probably pathogenic. These included V. fluvialis, V. hollisae, V. metschnikovii, V. minicus, V. salmonella and V. tubiashii. Together the application will be of significance in clinical diagnostic work, in the monitoring of vibriosis in fish farms and in quarantine.

INTRODUCTION: Since the eradication of smallpox in 1977, mass vaccination efforts against it have been discontinued. Thus, the majority of the younger population is susceptible to both smallpox virus and vaccinia virus (VV). The re-emergence or intentional release of smallpox will present a serious threat to global health. There are limited supplies of smallpox vaccine, which is associated with significant complications, and pooled anti-VV human immune globulin (VIG) that can be used as prophylaxis or to treat smallpox-exposed individuals. We are developing murine monoclonal antibodies (MAbs) able to neutralize VV. The developed MAbs may be useful in establishing a rapid diagnostic test for the detection of VV infection or providing the genetic materials needed for developing recombinant antibodies suitable for human use. METHODS: VV Western Reserve (WR) strain was propagated in HeLa or Chicken Embryo Fibroblast (CEF) cell lines, purified through a 36% sucrose cushion and inactivated by binary ethyleneimine (BEI). Female BABL/c mice were immunized with inactivated VV. Hybridoma cell lines (HCLs) were developed from spleen cells of the mice with high neutralizing antibody titers. Tissue culture supernatants from the developed HCLs were screened by Enzyme-Linked Immunosorbent Assay (ELISA) and Plaque Reduction Assay (PRA) for their abilities to produce neutralizing antibodies against VV. HCLs producing neutralizing antibodies were sub-cloned by limiting dilution method. Highly neutralizing MAbs were isotyped and purified. The effect of using increasing microgram amounts of each MAb or mixtures of two MAbs on VV neutralization has been determined. Specific target proteins recognized by MAbs were detected by western blot assay (WB). The abilities of the developed MAbs to neutralize other three VV strains, Large-variant (L-variant), IHD-W and New York City Board of Health (NYCBH), were measured. RESULTS: We have developed 261 HCLs producing anti-VV antibodies; 65 of them neutralized VV. Twelve HCLs were sub-cloned. We developed 79 sub-clones producing neutralizing MAbs. The majority of them were immunoglobulin IgG1/κ isotype. Four highly neutralizing MAbs were concentrated and purified. They were able to neutralize 50% of VV infection at 0.01-0.1 µg in PRAs. Synergistic effects on VV neutralization were observed when mixing two MAbs from clones, 1-E9-1-E4 and 2-B7-9-E6, at the amounts giving about 20% and 40% VV neutralization. Based on the WB results, the developed MAbs are recognizing 75 kilodalton (kDa), 45 kDa, 35 kDa or 8 kDa WR VV proteins. The abilities of the developed MAbs to neutralize other strains of VV varied. CONCLUSIONS: Several HCLs producing antibodies against VV were developed. Highly neutralizing MAbs against WR VV have been produced and purified. Virus neutralization is dose dependent and some of MAbs have synergistic neutralization effects on each other. Most of the MAbs were targeting the same three virus envelope proteins indicating that these proteins contain important epitope(s) responsible for the neutralizing effects by the developed MAbs. Variable neutralization abilities were observed on three other VV strains indicating their immunobiologic differences with WR VV strain. The developed MAbs may be used as a research tool to study VV pathogenesis or for the development of chimeric antibodies for clinical applications. / October 2006

Thesis (M. Phil.)--University of Hong Kong, 1988.

Thesis (M.D.)--University of Hong Kong, 1988.

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No description available.

published_or_final_version / Medicine / Master / Doctor of Medicine