Made available in DSpace on 2014-06-11T19:32:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-11Bitstream added on 2014-06-13T19:21:45Z : No. of bitstreams: 1 melo_lms_dr_sjrp.pdf: 6146654 bytes, checksum: 861736c4cd6f9884be922b051977e3fb (MD5) / O presente estudo avaliou a resposta de anticorpos contra diferentes antígenos de merozoíto e esporozoíto de Plasmodium vivax, relacionando com as variantes da porção repetitiva do domínio central do gene da Proteína Circunsporozoítica (CSP) do parasito (VK210, VK247 e P. vivax-like) e com os polimorfismos do HLA-DRB1 no hospedeiro humano. A resposta de anticorpos foi avaliada para peptídeos das regiões conservadas e centrais variáveis da CSP, da porção N-terminal da Proteína de Superfície do Merozoíto 1-MSP1 (Pv200L), e recombinante do Antígeno 1 de Membrana Apical (AMA-1) e a Proteína de ligação ao Duffy (DBP) por ELISA, em amostras de plasma de pacientes naturalmente infectados com P. vivax. Inicialmente nós avaliamos a distribuição destas variantes da CSP em cinco diferentes áreas da Amazônia a fim de entender sua atual dinâmica de transmissão. A variante VK210 continua sendo a mais prevalente em todas as áreas estudadas. No entanto, pela primeira vez documentamos a presença das variantes VK247 e P. vivax-like como infecções simples na Amazônia brasileira evidenciando um novo perfil distribuição destas, o que possa sugerir um processo de adaptação das mesmas. Quando comparamos a resposta de anticorpos e a infecção pelas variantes de P. vivax, não foram observadas associações significativas entre a presença de determinada variante da CSP e a freqüência de resposta de anticorpos contra os três peptídeos do merozoíto analisados, MSP1 (Pv200L), AMA-1 e DBP e nem contra as frações conservadas da CSP no esporozíto, N-terminal [N] e C-terminal [C]. A falta de associações significativas entre resposta sorológica contra esses peptídeos fornece informações promissoras quanto à utilização destes antígenos para o desenvolvimento de uma vacina contra malária. Todavia, a variação na porção central da CSP deve ser considerada... / The present study evaluated the antibody response against merozoite and sporozoite antigens of Plasmodium vivax and its relationship with the variants of the repetitive central region of the gene for Circunsporozoite protein (CSP) in parasite (VK210, VK247 and P. vivax-like) and, with the HLA-DRB1 polymorphisms in human host. The antibody response to synthetic peptides of the CSP conserved and variable regions and of the N-terminal portion of Merozoite surface protein - MSP1 (Pv200L), and, to recombinants peptides of the Apical Membrane Antige 1 (AMA-1) and of the Duffy Binding Protein (DBP) was evaluable by ELISA in plasma samples of malaria patients naturally infected with P. vivax. Firstly, we evaluated the CSP variants distribution among five different areas from Brazilian Amazon, in order to understand their current dynamic of transmissions. VK210 variant remains the most prevalent in all study areas. However, it is the first detection of VK247 e P. vivax-like variants as simple infection in the Brazilian Amazon, showing a new distribution profile, which may suggest an adaptation process of them. When comparing the antibody response and infection by variants of P. vivax, there were no significant associations between the presence of particular CSP variant and the frequency of antibody response against all three merozoite peptides analyzed, MSP1 (Pv200L), AMA-1, DBP and against the CSP conserved fractions in the sporozoite, N-terminal and C-terminal. The lack of significant associations among immune response against these peptides provides promising information regarding the use of these antigens for malaria vaccine development. On the other hand, the central variability of CSP should be considered to employment of this region as an immunogen, since the antibody response appears to be variant-specific. In order to evaluate the polymorphisms... (Complete abstract click electronic access below)

Nos últimos anos, estudamos vários aspectos da resposta imune naturalmente adquirida em indivíduos de diferentes áreas endêmicas da Região Amazônica expostos à malária. Para isso, utilizamos proteínas recombinantes baseadas em antígenos de formas sanguíneas de P. vivax, os quais têm sido considerados candidatos à vacina contra a malária vivax. No presente trabalho, nossos estudos imunoepidemiológicos concentraram-se em 396 indivíduos de uma comunidade rural da Amazônia ocidental brasileira, localizada no Estado do Acre, com o objetivo de realizar um estudo transversal e longitudinal da resposta de anticorpos contra um painel de proteínas recombinantes derivadas de merozoítos de P. vivax (MSP119, AMA-1, MSP3α e MSP3β). Para isso, os soros desses indivíduos foram testados por ELISA quanto ao reconhecimento das quatro proteínas recombinantes. As proporções de indivíduos na linha de base com anticorpos IgG contra MSP119, AMA- 1, MSP3α e MSP3β foram de 59,8%, 50,0%, 23,5% e 26,5%, respectivamente. Dentre esses indivíduos, apenas 10,9% tinham infecções por P. vivax, P. falciparum ou malária mista. No grupo de infectados por P. vivax, a proporção de respondedores foi maior para as proteínas recombinantes MSP119 e AMA-1, atingindo 78,6%, em ambos os casos. A proporção de indivíduos com anticorpos para cada uma das proteínas associou-se com o maior tempo de exposição à malária, exceto para a MSP3β. Além disso, a positividade foi mais alta nas áreas de maior risco de transmissão. Não observamos associações relevantes entre o genótipo do antígeno Duffy dos indivíduos e presença de anticorpos para as proteínas estudadas. No estudo longitudinal, observamos um aumento da prevalência de respondedores durante a parasitemia patente, sendo de 81,9%, 80,9%, 31,9% e 48,9% para a MSP119, AMA-1, MSP3α e MSP3β, respectivamente. Em conclusão, nossos resultados confirmam a alta antigenicidade dessas proteínas, o que pode ser de grande importância para futuros ensaios clínicos na região. / In recent years we studied various aspects of the naturally acquired immune response in individuals from different endemic areas of the Amazon region exposed to malaria. For this purpose we used recombinant proteins based on P. vivax blood stage antigens considered candidates for a vaccine against vivax malaria. In the present study, we focused on 396 individuals from a rural community in western Brazilian Amazon located at the state of Acre. We conducted a transversal and longitudinal study of the antibody response to a panel of recombinant proteins representing P. vivax merozoites surface antigens (MSP119, AMA-1, MSP3α and MSP3β). The sera of these individuals were tested by ELISA for the recognition of the four antigens mentioned above. The proportions of individuals at the baseline with IgG antibodies to MSP119, AMA-1, MSP3α and MSP3β were 59.8%, 50.0%, 23.5% and 26.5%, respectively. Among these individuals, 10.9% had patent malaria infections with either P. vivax or P. falciparum or both. Among individuals with patent P. vivax infection, the frequency of responders was high for MSP119 and AMA-1, (78.6% in both cases). Except in the case of MSP3β, the proportion of individuals with antibodies to each protein correlated with the time of malaria exposure. Also, the positivity was higher in areas of higher transmission levels. No relevant association was found between the Duffy genotypes and presence of antibodies to the different antigen. In longitudinal study, we observed an increased prevalence of responders during patent parasitemia, 81.9% 80.9% 31.9% and 48.9% to MSP119, AMA-1, MSP3α and MSP3β, respectively. In conclusion, our results confirm the high antigenicity of these proteins, which can be of great importance for future clinical trials in the region.

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Immune response provides vertebrates an important mechanism to fight pathogens and to reduce the incidence of diseases. Defining the molecular basis of antibody response may facilitate genetic improvement in the immune response of animals to pathogens. For almost 4 decades, antibody titers in response to challenge by sheep red blood cells (anti-SRBC) have provided an investigative tool in the efforts to define molecular mechanisms that underlie vertebrate immune response. The overall objective of this dissertation research was to identify DNA markers associated with anti-SRBC response in chickens. Specific objectives were: to develop a resource population for QTL analysis for anti-SRBC, to identify DNA markers and genes associated with primary anti-SRBC, and to evaluate the allelic frequencies in non-selected chicken populations of candidate markers associated with either high or low anti-SRBC response. These objectives tested the hypothesis that genetic control of a chicken's response to SRBC is polygenic. The resource population developed consisted of F1, backcross, and F2 derived from reciprocal crosses of birds from parental lines in the 28th generation of divergent selection for low (L) and high (H) anti-SRBC. The mean anti-SRBC titers of the parental lines were significantly different, with 11.5 for H and 2.6 for L (P<0.05). That for the 4 groups of F2 progeny ranged from 6.3 to 7.5, while those of the 8 groups of backcross progeny ranged from 3.9 to 13.3. Four of 555 random primers used to screen the parental H and L anti-SRBC lines were informative by amplifying seven line-specific fragments (P<0.0025). Each of the 7 line-specific fragments was converted to a sequence characterized amplified region (SCAR) within which single nucleotide polymorphisms (SNPs) were identified and tested for association with anti-SRBC. Only two of the seven SCARs in the parental lines were associated (P<0.05) with anti-SRBC level in the backcross resource population. Additionally, from analysis of the parental L and H anti-SRBC lines using microarrays, a total of 57 line-specific SNPs were also identified. Twenty of the line-specific SNPs were in and/or near genes previously reported to have immunity-related function. Microarray-based gene expression profiling of pooled RNA samples from L and H anti-SRBC birds identified three differentially expressed genes. In summary, this dissertation describes resources that include candidate SCARs and SNPs as well as differentially expressed genes that may be useful for the identification of genes that underlie antibody response. / Ph. D.

Skin is the largest immune organ and an ideal site to administer vaccines. However, by nature, skin is not permeable to antigens, which are macromolecules. The major hurdle in skin permeation is the outermost stratum corneum layer. Microneedles have proven feasible to create micron-sized channels in the epidermis of the skin, through which protein and plasmid DNA antigens can penetrate into the viable skin epidermis and dermis. However, the immune responses induced by microneedle-mediated transcutaneous immunization with protein or plasmid DNA alone are generally weak, and a vaccine adjuvant is often required to induce strong immune responses. Data from numerous previous studies have shown that nanoparticles as a vaccine carrier can significantly enhance the immunogenicity of antigens, but the feasibility of utilizing nanoparticles as a vaccine carrier to enhance the immune responses induced by microneedle-mediated transcutaneous immunization has rarely been studied. In this dissertation, using protein antigen (OVA) chemically conjugated onto the surface of solid-lipid nanoparticles and plasmid DNA (pCMV-beta, pVax/opt-BoNT/C-Hc50, and pCI-neo-sOVA) physically coated on the surface of cationic polymeric nanoparticles, we showed that the immune responses induced by microneedle-mediated transcutaneous immunization with protein antigens or plasmid DNA vaccines are significantly enhanced by delivering the proteins and plasmid DNA with nanoparticles. Importantly, microneedle-mediated transcutaneous immunization with proteins or plasmid DNA induces not only systemic immune responses, but also mucosal immune responses. In addition, it is generally believed that microneedles are safe. However, it remained unclear whether the micropores created by microneedles on the skin will also facilitate the permeation of microbes such as bacteria into the skin. In this dissertation, we also designed an unique ex vivo model to evaluate the permeation of live bacteria through mouse skin pretreated with microneedles. The results demonstrated that the risk of potential bacterial infection associated with microneedle treatment is not greater than that associated with a hypodermic needle injection. / text

The gonococcal transferrin binding proteins (Tbps) are two surface-exposed outer membrane proteins, TbpA and TbpB, which together function to remove and internalized iron from human transferrin. Iron is an essential nutrient to the gonococcus, without which it cannot survive. The Tbps have been established as virulence factors, demonstrating their importance in establishing infection. Both TbpA and TbpB are well conserved among gonococcal isolates, and have been considered potential vaccine targets. Vaccine studies with the closely related species Neisseria meningitidis, have demonstrated these proteins to be protective in murine challenge studies. Though the meningococcal Tbps have demonstrated promise, no similar gonococcal vaccine experiments have been conducted prior to the current studies. Here we demonstrate purification of recombinant TbpA and TbpB. These recombinant proteins were utilized to evaluate the human immune response to these proteins during natural infections, and their immunogenicity in murine vaccine studies. Our results demonstrate a paucity of antibodies elicited to these proteins during natural infections in serum and mucosal secretions from infected individuals. From this study we hypothesized the induction of both serum and genital antibodies to these proteins could serve to protect an individual from infection. To begin testing this hypothesis, we immunized mice both intranasally (IN) and subcutaneously (s.c.) with full-length Tbps in conjunction with the B subunit of cholera toxin (Ctb) as an adjuvant. We also performed another vaccine study using domains from both proteins in genetic fusions with Ctb and E. coli heat labile toxin IIb (LtbIIb). Both studies demonstrated that these antigens were immunogenic, as Tbp-specific antibodies were elicited in the serum and vaginal washes of female Balb/C mice. Intranasal immunization however was the only route with which we were able to elicit vaginal Tbp-specific IgA, and IgG, whereas subcutaneous immunization only elicited vaginal IgG. Furthermore, we found the full-length Tbps and the Ctb/LtbIIb chimeras were able to elicit bactericidal antibodies, which were also effective in killing heterologous gonococcal strains. This body of work comprises the first published study using the gonococcal transferrin binding proteins as vaccine antigens, and highlights their potential as vaccine antigens in the development of an efficacious gonococcal vaccine.

Porcine circovirus type 2 is a single stranded DNA virus that belongs to the genus Circovirus in the family Circoviridae. This virus is associated with many kinds of diseases in pigs and causes significant economic losses in swine-breeding. In this study, two approaches of vaccination were tested in order to develop an effective vaccine against PCV2. The first approach was to test DNA vaccines. For this purpose, eukaryotic expression plasmids encoding two form of PCV2 Cap protein were constructed. The expression plasmids encoding murine TNF-α and IFN-α1 were also prepared for co-immunization with antigen encoding plasmid to enhance the immune response. The second approach is based on the previous finding that chimeric pentamers of VP1 mouse polyomavirus capsid protein fused with PCV2 can induce protective immunity against PCV2. These chimeric pentamers were further modified by AA substitutions in PCV2 Cap immunodominant epitope in order to enhance protective antibody response directed against PCV2. The chimeric pentamers and DNA vaccines were tested for ability to induce antibody immune response against PCV2 in mice. The results showed that chimeric pentamers are more potent inducers of protective antibody immune response against PCV2 compared to DNA vaccines. However, the protective antibody...

Hantaviruses are found practically all over the world and cause hemorrhagic fevers in man. Each year about 150,000 people are hospitalized in these zoonotic infections which can be of two types: hemorrhagic fever with renal syndrome (HFRS) or hantavirus cardiopulmonary syndrome (HCPS), depending on the infecting virus. Hantavirus infections are emerging infectious diseases. That is, the number of reported cases of hantaviral disease is increasing, new hantaviruses are discovered continually, and already known hantaviruses are expected to spread to new areas. Therefore, knowledge and monitoring of these viruses are imperative from a public health perspective. In this thesis, the characterization of a local human Puumala (PUUV) virus isolate is described. Genetic and serological relationships to other hantaviruses are investigated and the viral protein interactions, critical for genome packaging and assembly, are studied. We found that the nucleotide and amino acid sequences of the local PUUV strains are significantly different from the PUUV prototype strain Sotkamo, a difference that indicates that there might be a risk of misdiagnosing PUUV infected patients when using reagents derived from the prototype strain. These data contributed to the introduction of locally derived diagnostic tools to the Laboratory of Clinical Virology at the Umeå University hospital, which is the reference centre for hantaviral diseases in Sweden. Furthermore, when studying the underlying mechanisms of genome packaging, we identified several regions and amino acids absolutely required for nucleocapsid protein interactions. Also, a region that appeared to regulate this interaction was discovered. Finally, the serological immune responses in DNA-vaccinated mice and PUUV infected patients were investigated. We found that the cross-reactive antibody response in vaccinated mice and in infected individuals was unique and independent of homologous titres. Furthermore, four immunodominant epitopes with specific cross-reactive characteristics were identified. Our findings have highlighted the complexity of the serological immune responses to hantavirus infections, and they emphasize the importance of customizing the diagnostic tools and performing clinical analyses on locally derived strains. In conclusion, we believe that these results are valuable in the development of new serological, genetic, and epidemiological tools.

The Plasmodium vivax Duffy Binding Protein (DBP) is the ligand in the major pathway for P. vivax invasion of human reticulocytes, making it an appealing vaccine candidate. Region II of DBP (DBP-RII) is the minimal portion of the ligand that mediates recognition of the Duffy Antigen Receptor for Chemokines (DARC receptor) on the reticulocyte surface and constitutes the primary vaccine target. Analysis of natural variation in the coding sequences of DBP-RII revealed signature evidence for selective pressure driving variation in the residues of the putative receptor-binding site. We hypothesize that anti-DBP immunity in P. vivax infections is strain-specific and hindered by polymorphic residues altering sensitivity to immune antibody inhibition. To comprehend the human IgG response following P. vivax infections we investigated the specificity of IgG in Pursat Province, Western Cambodia. Using ELISAs, we quantified the antibody titer against five variant alleles of DBP-RII. We also sequenced the DBP-RII of the field isolates to determine their relationship to the variant alleles used in the ELISAs. When correlating the IgG titer between the DBP variants a strain-specific immune response was observed in patients with a high antibody titer to DBP-RII_AH as compared to the other variants. This was different from the correlation of high antibody titers between DBP-RII_P and DBP-RII_7.18 (ρ=0.88, p-value<0.0001) and DBP-RII_P and DBP-RII_O (ρ=0.87, p-value<0.0001). There appeared to be little correlation between specific polymorphic residues and IgG titer. Understanding the immune response to the polymorphisms within PvDBP will allow further identification of epitopes to enable the production of a more effective P. vivax vaccine

Aeromonas hydrophila is an opportunistic pathogen that causes a wide range of symptoms and diseases in fish. Development of a commercial vaccine has been problematic due to the heterogenicity between isolates of A. hydrophila. A new approach using immunoproteomics was used in this study to try to develop a vaccine that would protect against a wide range of A. hydrophila strains. The virulence of 14 isolates of A. hydrophila from different geographical regions was determined in common carp (Cyprinus carpio) indicating that 6 isolates were virulent, while 8 isolates were avirulent. Expression of cellular and extracellular products (ECP) of six of these isolates (4 virulent and 2 avirulent isolates) were examined following culture of the bacterium in vitro, in tryptic soy broth, and in vivo, in dialysis tubing placed within the peritoneal cavity of carp. Two types of molecular weight cut off tubes (25 and 100 kDa) were used for the implants. Whole cell (WC), outer membrane protein (OMP) and ECPs of the bacteria grown in vitro and in vivo were analysed by 1 dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (1D SDS-PAGE). Additionally, 2D SDS-PAGE was used to analyse WC preparations of A. hydrophila grown in vitro and in vivo. The production of unique proteins and up and down-regulation of protein expression were observed in all the preparations of bacteria grown in vitro and in vivo. Unique bands were seen in the 1D SDS-PAGE at 58 and 55 kDa for WC and OMP preparations, respectively, for all the isolates cultured in vivo. Bands of increased intensity were observed at 70, 55, 50 and 25 kDa with WC preparations for the virulent isolates cultured in vivo. Analysis of WC preparations by 2D SDS-PAGE indicated differences in the expression of spots between bacteria cultured in vitro and in vivo. A number of unique spots, mostly between 30 and 80 kDa with pI values ranging from 5.0-6.0 were observed in the bacteria grown in vivo. The protein profiles of different preparations (WC, OMP, ECP) of bacteria cultured in vitro and in vivo were screened by 1D Western blot using antibodies from carp artificially infected with different isolates of A. hydrophila to identify potential vaccine candidates. The WC preparations of A. hydrophila (T4 isolate) grown in vitro were also analysed by 2D Western blot. A 50 kDa protein of A. hydrophila was found to be the most immunogenic molecule in both WC and OMP of bacteria grown both in vitro and in vivo. The protection efficacy of this protein was determined in goldfish by vaccinating fish with electro-eluted 50 kDa protein then challenging the fish with A. hydrophila. Fish were also passively immunised with fish sera raised to the 50 kDa protein and then challenged. The relative percentage survival (RPS) was 67 % in the vaccination trial, while the results were inconclusive for the passive immunisation trial. The 50 kDa protein was confirmed to be the S-layer protein of A. hydrophila following identification using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Recombinant S-layer protein was then produced and the cross-protection efficacy of this protein against six virulent isolates of A. hydrophila was confirmed in a large scale vaccination trial using carp. The RPS value for the 6 isolates of A. hydrophila ranged from between 56 and 87 %. The results of this project suggest that the immunogenic S-layer protein of A. hydrophila could be used as a common antigen to protect fish against infection by different isolates of this pathogenic bacterium.