Orientador: Marcelo Lancellotti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-19T19:47:46Z (GMT). No. of bitstreams: 1 Alves_DaniloAntonini_M.pdf: 4789463 bytes, checksum: cb7f3cabfd7df63e9dc00316cb7c8a10 (MD5) Previous issue date: 2012 / Resumo: Vesículas da membrana externa ou outer membrane vesicles (OMV) são nanopartículas liberadas no meio de cultura durante o crescimento bacteriano resultantes de evaginações da membrana externa. A OMV é composta por antígenos presentes na membrana externa bacteriana, como porinas e lipo-oligossacarídeos - LOS, proporcionando a estas estruturas um efeito imuno-estimulatório, sendo alvo potencial para a produção de vacinas. Este trabalho teve como objetivo analisar a utilização de OMV de Neisseria meningitidis IAL 2443, linhagem pertencente ao sorogrupo B causadora de meningites no estado de São Paulo, com nanopartículas de sílica mesoporosa SBA-15 e SBA-16 no processo de imunização vacinal. Utilizou-se o processo fermentativo em estado semi-sólido para o crescimento bacteriano e um processo de ultracentrifugação para isolamento da OMV. Comparou-se a produção de OMV de linhagens de N. meningitidis selvagens IAL 2443 e C2135 e mutante knock-out para o gene responsável pela produção de pilina - C2135_pilE. A atividade imunológica foi verificada por meio da imunização em camundongos Swiss e a verificação da citotoxicidade foi realizada em cultura celular utilizando células VERO e NHI 3T3. Os resultados mostraram que as diferentes linhagens de N. meningitidis possuem cinéticas de produção de OMVs distintas em tempo e quantidade. A não expressão de pilE também afeta a cinética da produção dessas estruturas. O uso de adjuvantes de sílica mesoporosa SBA- 15 e SBA- 16 com a OMV IAL 2443 aumenta o reconhecimento pelo sistema imunológico, consequentemente elevando o número de anticorpos específicos frente a mesma cepa bacteriana e a outras linhagens do mesmo sorotipo e sorotipos diferentes. O teste de citotoxicidade em células VERO e NHI 3T3 demonstrou inocuidade nas preparações com SBA- 15 e SBA- 16, atestando a segurança no uso destas preparações como adjuvantes vacinais. O estudo demonstrou que a metodologia utilizada para produção de OMV é vantajosa do ponto de vista quantitativo e econômico e o uso de SBA- 15 e SBA- 16 apresenta potencial como adjuvante em vacinas baseadas em OMV / Abstract: Outer membrane vesicles or OMV are nanoparticles released into the culture medium during bacterial growth resulting from evaginations of the outer membrane. The OMV consists of antigens present in the bacterial outer membrane, like porins and lipooligosaccharides - LOS, these structures provide an immuno-stimulatory effect, and potential target for vaccine production. This study aimed to analyze the use OMV of Neisseria meningitidis IAL2443, belonging to serogroup B strain causing meningitis in São Paulo, as vaccine using the mesoporous silica SBA-15 and SBA-16 in the immunization process. Fermentation process was used in semi-solid state for bacterial growth and a process of ultracentrifugation for the isolation these OMV. It was compared to OMV production of strains of N.meningitidis strains IAL 2443 and C2135, and knock-out mutant for the gene responsible for producing pilin - C2135_pilE. The immunological activity was measured by immunization in Swiss mice and verification of cytotoxicity was performed in cell culture using VERO cells and NIH 3T3. The results showed that different strains of N. meningitidis have OMVs kinetics of production of different time and quantity. The expression does not pile also affects the kinetics of production of these structures. The use of adjuvants mesoporous silica SBA-15 and SBA-16 with the IAL2443 OMV increases the recognition by the immune system, thus bringing the number of specific antibodies against the same bacterial strain and other strains of the same serotype and different serotypes. The cytotoxicity test in NIH 3T3 cells showed VERO and safety in preparation adjuvanted with SBA-15 and SBA-16, confirming the safe use of these preparations as vaccine adjuvants. The study showed that the methodology used for the production of OMV is advantageous from the point of view of quantity and cost and use of SBA-15 and SBA-16 has potential as an adjuvant in vaccines based on OMV / Mestrado / Bioquimica / Mestre em Biologia Funcional e Molecular

Bakgrund: Ventrikeldränage används inom neurokirurgisk vård för medicinsk behandling, dränering av likvor samt mätning av intrakraniellt tryck. En infektion relaterat till ett ventrikeldränage kan vara livshotande och ge permanenta skador hos patienten. Syfte: Att analysera dokumenterade skillnader i ventrikeldränagerelaterade infektioner, vårdtid och mortalitet, före och efter införande av nya hygienrutiner - ett åtgärdspaket. Metod: Ett åtgärdspaket med medicinska- och omvårdnadsåtgärder har med hjälp av genombrottsmetoden tagits fram för att minska de ventrikeldränagerelaterade infektionerna. Studien är kvantitativ med empirisk ansats. Konsekutivt urval av patienter som erhållit ventrikeldränage under första halvåret 2008 samt första halvåret 2009. Totalt 150 patienter har ingått i studien. Data har analyserats med deskriptiv och analytiska statistik. Resultat: De vårdrelaterade infektionerna minskade mellan de två mätperioderna. Resultatet visar inga tydliga samband mellan vilken av åtgärderna som haft effekt på minskningen av infektionerna. Däremot ses att de som haft bättre följsamhet till åtgärdspaketet har drabbats av färre infektioner. Signifikant samband finns mellan riskhandhavande som spolning av dränage och läckage vid dränaget instickställe, samt infektioner. Slutsats: Studien indikerade i att de ventrikeldränagerelaterade infektionerna har minskat efter insättande av åtgärdspaketet. / Background: External ventricular drainage (EVD) is used within neurosurgical care for medical treatment, temporary drainage of cerebrospinal fluid (CSF) and to measure intracranial pressure. An infection related to an EVD can be life threatening and cause permanent damage to the patient. Objective: To analyze the documented differences in EVD related infections, length of hospitalization and mortality, before and after the introduction of new hygiene routines – a bundle. Method: A package with medical and nursing interventions has been developed using a breakthrough method to reduce EVD related infections. The study is quantitative and has an empirical approach. A consecutive sample of patients who received an EVD during the first half of 2008 and 2009 respectively were chosen. In total 150 patients were included in the study. The data was analyzed with descriptive and analytical statistics. Results: The EVD related infections have decreased between the two time periods. No clear correlation between which actions had a direct effect on the reduction of infections was found. Those patients that had a better adherence to the package suffered fewer infections. A prevalent correlation was found between high risk actions such as flushing the EVD and CSF leaks from the site of puncture, and subsequent infections. Conclusion: The study indicates that the EVD related infections have decreased after the implementation of the package.

Entre 2 et 5% des enfants de 6 mois à 5 ans présentent au moins un épisode de Crise d’Épilepsie en contexte Fébrile (CEF). Bien que généralement bénignes, ces crises sont associées à un risque d’urgences neurologiques graves et curables dont l’élimination requiert la réalisation d’examens complémentaires douloureux et/ou irradiants. Actuellement, ce risque est évalué en fonction de trois facteurs : l’âge de l’enfant, le caractère simple ou complexe de la crise, et l’examen clinique.Cette thèse avait pour objectif de tester l’hypothèse que parmi les enfants consultant pour une CEF, seuls ceux avec un examen clinique anormal présentent un risque d’urgence neurologique grave et urgent. Pour ce faire, nous avons créé un outil informatique permettant une recherche exhaustive de cas parmi un million de dossiers médicaux informatisés dans sept services d’urgences pédiatriques entre 2007 et 2011. Nous avons alors identifié : les visites d’enfants présentant une CEF. Nous avons ensuite évalué le risque d’urgence neurologique grave et curable associé à ces visites, notamment lorsque l’examen clinique au décours était normal. Nous n’avons retrouvé aucune urgence neurologique grave et curable parmi les enfants consultant pour une CEF avec un examen clinique normal au décours, quels que soient l’âge et les caractéristiques de la crise. Ce travail de thèse associé aux données de la littérature confirme notre hypothèse et souligne la nécessité de recommandations quant à la prise en charge de ces enfants. Enfin, cette thèse constitue l’occasion de mener une réflexion méthodologique quant à l’utilisation de dossiers médicaux informatisés pour la recherche clinique. / Febrile seizures (FS) affect 2% to 5% of children aged 6 months to 5 years of age. Although FS are usually benign, they are associated with serious treatable neurological emergencies. Nowadays, three factors are used to evaluate this risk: the age of the child, whether the FS is simple or complex and the features of the clinical exam. The performance of a lumbar puncture and an emergent neuroimaging are required in order to rule out these emergencies. However, a lumbar puncture is painful and neuroimaging is irradiant. The objective of this thesis was to investigate the hypothesis that among children experiencing a FS, only those with an abnormal clinical exam are at risk of serious, treatable neurological emergencies. We first created an informatics tool in order to exhaustively search for cases among more than one million electronic medical records from seven pediatric emergency departments (PED) between 2007 and 2011. Then, we identified visits of children with a FS. Finally, we evaluated the proportion of serious, treatable neurological emergencies associated with these visits, and more specifically with visits of children with a normal clinical exam.We found no serious treatable neurological emergencies among children visiting the ED for a FS with a normal clinical exam, whatever the age and the features of the seizure were. The studies described in this thesis associated with the available data in the literature support our hypothesis and highlight the need of guidelines regarding the management of these children. Finally, this thesis gives us the opportunity to discuss some considerations on the use of electronic medical records for clinical research.

Einleitung: Die Steroid-responsive Meningitis Arteriitis (SRMA) ist eine der häufigsten entzündlichen Erkrankungen des zentralen Nervensystems des Hundes. Ziele der Untersuchungen: Ziel der vorliegenden Arbeit ist es Rasse- und Geschlechtsprädispositionen anhand der Gesamtpopulation in Deutschland sowie epidemiologische und klinische Faktoren hinsichtlich der Rezidivrate von SRMA-Patienten zu untersuchen und zu beschreiben. Material und Methoden: Im Rahmen der ersten Teilstudie werden die Daten von 74 Hunden mit SRMA retrospektiv erhoben und einer von drei Gruppen zugeordnet: (1) ohne Rezidiv; (2) mindestens ein Rezidiv und (3) unbekannter Rezidivstatus. Die folgenden Parameter werden für die ersten beiden Gruppen beschrieben: Geschlecht, Alter, Rasse, Körpergewicht, Analyse des Liquor cerebrospinalis (Proteinkonzentration, Anzahl der kernhaltigen Zellen, Prozentsatz an Neutrophilen, Immunglobulin A (IgA) und C-reaktives Protein (CRP) bei Erstvorstellung), IgA und CRP im Serum bei Erstvorstellung sowie die Anzahl der kernhaltigen Zellen und CRP im Liquor cerebrospinalis und CRP im Serum bei der Kontrolluntersuchung nach drei Monaten. In der zweiten Teilstudie werden die Daten von 153 Hunden mit Steroid-responsiver Meningitis-Arteriitis retrospektiv in einer Multicenterstudie analysiert. In dieser Studie wird untersucht, ob einzelne erkrankte Hunderassen (n ≥ 5) überproportional häufig, im Vergleich zur Rasseverteilung in der Gesamtpopulation der Hunde in Deutschland, vertreten sind. Als Datengrundlage wird die Welpenstatistik des Verbandes für das deutsche Hundewesen (VDH) des Jahres 2016 und die Anzahl der im Haustierregister Tasso e. V. (Stand 2018) gemeldeten Hunde verwendet. Des Weiteren wird der Einfluss des Geschlechts in Hinsicht auf die Erkrankungsrate von SRMA-Patienten untersucht. Bezüglich des Auftretens eines oder mehrerer Rezidive werden folgende mögliche Einflussfaktoren untersucht: Geschlecht, Gewicht, Alter bei Erstvorstellung, zeitlicher Abstand zur letzten Impfung, Zeitspanne zwischen Symptombeginn und Erstvorstellung, Symptome (reduziertes Allgemeinbefinden, zervikale Dolenz, Fieber, neurologische Defizite), Ergebnisse der Analyse des Liquor cerebrospinalis bei Erstvorstellung (Anzahl kernhaltiger Zellen und deren Differenzierung, Eiweißkonzentration), Konzentrationen von IgA und CRP in Serum und Liquor cerebrospinalis bei Erstvorstellung, angewandte Immunsuppressiva, Ansprechen auf die Therapie und die Nachbeobachtungszeit sowie die Todesrate infolge der Erkrankung oder ihrer Therapie oder der daraus folgenden Euthanasie. Ergebnisse: Die Ergebnisse der vorliegenden Arbeit zeigen, dass in Hinblick auf die Rasse ein signifikanter Einfluss auf die Entstehung von SRMA (p < 0,05) besteht. Beagle und Boxer erkranken in Relation zur Gesamtpopulation in Deutschland häufiger als andere Hunderassen. Rezidive treten bei ungefähr einem Drittel der Hunde in beiden Teilstudien auf. Männliche Hunde haben ein signifikant höheres Risiko an SRMA zu erkranken (p < 0,005). Im Gegensatz dazu erleiden weibliche Hunde signifikant häufiger ein Rezidiv (p = 0,02). In der ersten Teilstudie erleiden 62,5 % einen Rückfall, 25,0 % zwei Rückfälle, 8,3 % drei Rückfälle, 4,2 % vier Rückfälle. 55,4 % der Patienten waren rezidivfrei und bei 12,2 % war der Rückfallstatus unbekannt. Patienten mit einer Prednisolon-Monotherapie erleiden seltener ein Rezidiv als bei einer Kombination von Prednisolon und Azathioprin (p < 0,05). Sowohl jüngere SRMA-Patienten bei Erstvorstellung (p = 0,071) als auch eine niedrigere Konzentration des CRP im Serum (p = 0,081) bei Erstvorstellung scheinen mit einer Tendenz des Auftretens von Rezidiven assoziiert zu sein. Bei Hunden ohne Rezidiv war das CRP in Serum bei 100 % und Liquor cerebrospinalis bei 90 % der Hunde zur Kontrolle nach drei Monaten normal. Aber auch bei Rezidivpatienten war das CRP zu diesem Zeitpunkt bei 80 % der Hunde im Serum und bei 75 % im Liquor cerebrospinalis normal. Somit erfordert ein erhöhtes CRP im Serum oder Liquor eine Fortsetzung der Therapie, während ein normales CRP im Serum oder Liquor zum Therapieende einen zukünftigen Rückfall nicht ausschließt und damit als Indikator für ein mögliches Rezidiv ungeeignet ist. Schlussfolgerungen: Die Ergebnisse dieser Untersuchung ermöglichen eine bessere Besitzeraufklärung über den möglichen weiteren klinischen Verlauf erkrankter Hunde und das Risiko eines späteren Rezidivs. Die ermittelten Rasse- und Geschlechtsprädispositionen erleichtern die Diagnosestellung einer Steroid-responsiven Meningitis-Arteriitis und untermauern teilweise die Ergebnisse vorangegangene Studien.

Cryptococcus neoformans, an opportunistic fungal pathogen ubiquitously present in the environment, causes cryptococcal meningitis (CM) mainly in immunocompromised patients, such as AIDS patients. We aimed to identify disease-associated cryptococcal protein antigens targeted by the human humoral immune response. Therefore, we used sera from Colombian CM patients, with or without HIV infection, and from healthy individuals living in the same region. Serological analysis revealed increased titers of anti-cryptococcal IgG in HIV-negative CM patients, but not HIV-positive CM patients, compared to healthy controls. In contrast, titers of anti-cryptococcal IgM were not affected by CM. Furthermore, we detected pre-existing IgG and IgM antibodies even in sera from healthy individuals. The observed induction of anti-cryptococcal IgG but not IgM during CM was supported by analysis of sera from C. neoformans-infected mice. Stronger increase in IgG was found in wild type mice with high lung fungal burden compared to IL-4Ra-deficient mice showing low lung fungal burden. To identify the proteins targeted by human anti-cryptococcal IgG antibodies, we applied a quantitative 2D immunoproteome approach identifying cryptococcal protein spots preferentially recognized by sera from CM patients or healthy individuals followed by mass spectrometry analysis. Twenty-three cryptococcal proteins were recombinantly expressed and confirmed to be immunoreactive with human sera. Fourteen of them were newly described as immunoreactive proteins. Twelve proteins were classified as disease-associated antigens, based on significantly stronger immunoreactivity with sera from CM patients compared to healthy individuals. The proteins identified in our screen significantly expand the pool of cryptococcal proteins with potential for (i) development of novel anticryptococcal agents based on implications in cryptococcal virulence or survival, or (ii) development of an anti-cryptococcal vaccine, as several candidates lack homology to human proteins and are localized extracellularly. Furthermore, this study defines preexisting anti-cryptococcal immunoreactivity in healthy individuals at a molecular level, identifying target antigens recognized by sera from healthy control persons.

Meningococcal disease, caused by the bacterium Neisseria meningitidis, is an important cause of morbidity and mortality in young children and adolescents worldwide. There are 12 serogroups with most disease due to meningococci expressing one of five capsular polysaccharide antigens corresponding to serogroups A, B, C, Y and W135. In Europe, the majority of disease-causing strains are of serogroups B and C. No comprehensive vaccine is available against the bacterium due to the difficulty in producing serogroup B vaccines. A number of countries, e.g. UK and the Republic of Ireland have implemented routine meningococcal conjugate C (MCC) vaccine strategies. Due to the high proportion of disease accounted for by serogroup B in Europe and other developed countries, much research is currently being carried out to unearth vaccine candidates that would be protective and give as wide coverage as possible. Such candidates include the antigens PorA, FetA and factor H-binding protein. Potential drawbacks with antigens such as these which are under immune selection are high degrees of variability and lack of cross-immunity. Determination of the distribution, both geographically and temporally, of antigens and their association with clonal complex can aid in the formulation of novel vaccines and assess their potential coverage across Europe. Serological typing schemes involving characterisation of the polysaccharide capsule (serogroup) and outer membrane proteins such as PorA (serosubtype) and PorB (serotype) have been used for a number of years with some success. However, drawbacks associated with these methods include insufficient discrimination, limitations in panels of monoclonal antibodies used in the typing procedures and difficulty in comparison of results among labs. Consequently, in recent years genotypic methods such as multi-locus enzyme electrophoresis (MLEE) and subsequently multi-locus sequence typing (MLST) have been developed. These methods measure the variation in slowly evolving housekeeping genes whereas serological methods measure variation in antigens which are under immune pressure and are therefore more diverse. Combination of phenotypic and genotypic typing methods can offer high levels of discrimination. Molecular studies into meningococcal diversity have offered many important insights into its population biology, which have implications for prevention and control of meningococcal disease. These have included the identification of hyperinvasive lineages and the correlation of genetic type with antigenic type and disease epidemiology. The EU-MenNet programme was established as a pan-European infrastructure for the research and surveillance of European meningococcal disease. Its aim was to coordinate and disseminate the latest molecular isolate characterisation techniques (MLST) and electronic data transfer via the Internet to exploit epidemiological and population genetic studies. Within the EU-MenNet, the European Meningococcal MLST Centre (EMMC) was set up to carry out molecular typing — MLST, PorA and FetA — of European disease isolates from 18 countries over three years 2000, 2001 and 2002. The output of this project will be the largest representative molecular epidemiological study of meningococcal disease in Europe. Assessment of the data produced will give insights into the geographic and temporal distribution and structuring of disease-associated clonal complexes and antigens and their associations. This will give an indication of the meningococcal disease population in Europe and will be invaluable for the current, and ongoing, development and introduction of new meningococcal vaccines.

Neisseria meningitidis causes 500,000 cases of meningitis and septicaemia annually worldwide, with a mortality rate of approximately 10%. Most disease in developed countries is caused by serogroup B infection, against which there is no universal vaccine. Opa proteins are major meningococcal outer membrane proteins, and a limited number of Opa variants have been associated with hyperinvasive serogroup B meningococci, suggesting their use as a potential novel vaccine. Immunisation of mice with recombinant Opa elicited high levels of meningococcal-specific serum bactericidal antibody (SBA), demonstrating proof in principle of this approach. Opa proteins mediate bacterial adherence to host cells and modulate human cellular immunity, and there are conflicting data regarding their effects on CD4⁺ T cells. opa genes from N. meningitidis strain H44/76 were cloned into the plasmid vector pBluescript, disrupted using antibiotic resistance cassettes and transformed into H44/76 to sequentially disrupt the four opa genes. This produced a unique panel of 15 isogenic Opa-deficient strains, including an Opa-negative strain, which enabled investigation of the immunomodulatory role of surface-expressed Opa proteins. There was no consistent effect of Opa expressed on the surface of OMVs and inactivated bacteria on CD4⁺ T cells, with significant heterogeneity of responses between individuals. The rate of Opa phase variation was between 10^-3 and 10^-4, and increased 180-fold following transformation of bacteria with unrelated DNA. These data support further investigation of Opa as a potential meningococcal vaccine component, and highlight the importance of host and bacterial factors in the development of OMV vaccines.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Cette thèse retrace le développement du vaccin antiméningococcique A par l’Institut Mérieux de Lyon entre 1963 et 1975. Dans un premier temps, nous présentons la maladie et la menace de santé publique qu’elle représente spécifiquement en Afrique subsaharienne, nécessitant le développement d’un vaccin défendu par le médecin militaire français Lapeyssonnie. Nous retraçons l'histoire de la collaboration entre l'Organisation mondiale de la Santé, l'Institut Rockefeller, le Centre International de Référence pour les Méningocoques (Pharo) et l'Institut Mérieux qui commercialisera avec succès un vaccin. Nous concluons avec le programme massif de vaccination mené au Brésil en 1974-75 dans le cadre duquel 80 millions de personnes ont été vaccinées contre la méningite pour tenter d’arrêter une épidémie mortelle de la maladie.Nous analysons cette histoire avec le concept de ‘doable problems’ développé par Joan Fujimura. Cette approche nous permet d'échapper à une simple ‘narration du progrès’ de la découverte d'un vaccin. Au lieu de cela, l'analyse en termes de niveaux d'organisation du travail et les concepts clefs d'articulation et d'alignement mettent en évidence un certain nombre d'aspects intéressants, notamment l'importance de la collaboration entre groupes et individus, ainsi que des hypothèses implicites sur la validité des différentes approches de la production vaccinale. Cette approche analytique nous permet de mettre en évidence des aspects sociaux pour compléter l’histoire technique du développement et de l’utilisation du vaccin au cours de cette période / This thesis recounts the development of a meningococcal A vaccine by the Lyon-based company Institut Mérieux between 1963 and 1975. First, we present the disease and the public health threat it posed specifically in sub-Saharan Africa giving rise to an effort to develop a vaccine championed by the French military doctor Lapeyssonnie. We trace the history of the collaboration between the World Health Organisation, the Rockefeller Institute, the International Reference Center for the Meningococcus (Pharo) and the Institut Mérieux, the company that would successfully bring a vaccine to market. We conclude with the massive vaccination programme carried out in Brazil in 1974-75 in which 80 million people were vaccinated against meningitis in an attempt to stop a deadly epidemic of the disease. We analyse this history in terms of the concept of ‘doable problems’ developed by Joan Fujimura. This approach allows us to escape the simple ‘progressive’ narrative of the discovery of a vaccine. Instead, the analysis in terms of levels of work organization and the key concepts of articulation and alignment bring to light a number of interesting aspects, notably the importance of collaboration between groups and individuals as well as implicit assumptions concerning the validity of the different approaches to vaccine production. This analytical approach allows us to bring social aspects to the fore to complement the technical history of the development and use of the vaccine in this period

A tecnologia de conjugação melhorou a imunogeniddade de vacinas constituídas de polissacarídeo, especialmente em crianças. Polissacarídeos conjugados a proteínas carregadoras, como o toxóide tetânico, induzem resposta imunológica dependente de célula T e memória imunológica de longa duração. No entanto, esta tecnologia apresenta custo elevado. Assim, foi investigada a capaddade dos lipossomos de aumentar a resposta imunológica ao polissacarídeo C de Neisseria meningitidis (PSC). Camundongos foram imunizados com Iipossomos contendo PSC, conjugado toxóide tetânico-PSC ou PSC livre como controle, com dose de reforço constituída de PSC livre. Foram gerados anticorpos IgG e IgM contra PSC nos camundongos imunizados com conjugado ou Iipossomo. Os resultados mostram que lipossomos contendo PSC têm potencial para substituir a vadna conjugada toxóide tetânico-PSC. / Conjugation technology has improved the immunogenicity of polysaccharide vaccines, specially in small children. Polysaccharides conjugated to various carrier proteins, e.g. tetanus toxoid, stimulate a T cell-dependent antibody response and induce a long-term immunological memory. However, protein-polysaccharide conjugation technology is expensive and this could constitute an important drawback. Thus, immunopotentiation of Neisseria meningitidis serogroup C polysaccharide (PSC) by use of liposomes as an alternative to protein-polysaccharide C conjugates was investigated. Mice were immunized with liposomes containing PSC or tetanus toxoid-PSC conjugate or free PSC as control and boosted with free PSC. Immunogenicity of these different preparations was compared with each other. Conjugate and liposome containing PSC induced both IgG and IgM antibodies against the polysaccharide. These results show that liposomes containing entrapped PSC have potential to be used as an alternative to tetanus toxoid-PSC conjugate vaccine.