Intimina é uma adesina de natureza protéica das bactérias diarreiogênicas Escherichia coli enteropatogenica (EPEC) e enterohemorrágica (EHEC), capazes de induzir a lesão \'attaching e effacing\' em enterócitos. Os principais subtipos de intiminas de EPEC e EHEC prevalentes no Brasil são α, β e γ. Nosso objetivo foi investigar a transferência de anticorpos maternos anti-intiminas aos recém-nascidos de mães saudáveis de São Paulo, Brasil. Foram pesquisados anticorpos SIgA no colostro e IgG no soro de 50 mulheres saudáveis e no soro de cordão umbilical de seus recém-nascidos, por ELISA utilizando como antígeno proteínas recombinantes purificadas das regiões conservadas e variáveis de intiminas α, β e γ. As concentrações de anticorpos no colostro foram superiores quando comparadas com as concentrações do soro para todos os tipos de intiminas. Não se observaram diferenças estatísticas entre as concentrações de anticorpos reativos com as diferentes intiminas nas amostras de colostro. As concentrações de anticorpos reativos com a região conservada da intimina foram significativamente mais elevadas em comparação com as regiões variáveis no soro dos grupos de mães e de recém-nascidos. Houve alta correlação entre todos os anticorpos anti-intiminas nas amostras de colostro. Comparando-se as concentrações de anticorpos séricos, os coeficientes foram maiores entre anti-α e anti-β que entre os outros pares. Nossos resultados confirmam a transferência de anticorpos maternos para o recém-nascido pela placenta e pelo aleitamento materno e reforça o efeito protetor da amamentação contra infecção por EPEC. / Intimin is a proteic adhesin of enteropatogenic (EPEC) and enterohemorragic (EHEC) Escherichia coli, capable of inducing attachment and effacement lesion in enterocytes. The main subtypes of intimins of EPEC and EHEC prevalent in Brazil are α, β and γ. Our aim is to investigate the transference of maternal anti-intimin antibodies to the newborns of healthy mothers from Sao Paulo, Brazil. IgG and SIgA antibodies were determined in sera and colostrum from 50 healthy women and cord sera from their newborns, by ELISA using as antigens purified recombinant proteins, conserved and variable regions of α, β and γ intimins. The IgA antibody concentrations of colostrum are higher than IgG antibodies in serum for all intimins and there were no statistical differences between them in colostrum samples. The concentrations of antibodies reactive with the conserved region of intimin are significantly higher compared to the variable regions in the sera groups, mothers and newborns. There were high correlation coefficients between all the anti-intimins antibodies in colostrum samples. In the comparison of the seric antibody concentrations, the coefficients were higher between anti-α and anti-β than all the other pairs. Our results confirm the transference of maternal antibodies to the newborns by placenta and breastfeeding and reinforce the high protection effect of breastfeeding against EPEC infection.

Das humorale Immungedächtnis wird von reifen Plasmazellen des Knochenmarks vermittelt, welche bei Immunreaktionen aus aktivierten B-Lymphozyten gebildet werden. Dabei sind im Blut Plasmablasten als unmittelbare Vorläufer der Plasmazellen nachweisbar, die von dort aus in das Knochenmark einwandern. Anhand der durchflusszytometrischen Detektion spezifischer Plasmablasten gelang es hier, das simultane Auftauchen von Wellen neu generierter, migratorischer Plasmablasten und reifer, nicht-migratorischer Plasmazellen im Blut eine Woche nach einer Tetanusimpfung nachzuweisen. Plasmablasten und Plasmazellen lagen stets im Gleichgewicht vor, wodurch auf die stöchiometrische Mobilisierung reifer Plasmazellen des Knochenmarks durch systemisch induzierte Plasmablasten geschlossen wurde. Ein solcher Verdrängungsmechanismus wird hier erstmalig als Anpassungsmechanismus des humoralen Immungedächtnisses dargestellt, der die Aufnahme neuer Spezifitäten in das Gedächtnis unter Wahrung der Stabilität präexistierender Spezifitäten erlaubt. Anders als systemisch induzierte Plasmablasten, weisen Plasmablasten, die im immunologischen Ruhephase zirkulieren, Kennzeichen mukosaler Immunreaktionen auf: sie exprimieren IgA sowie die mukosalen Zellmigrationsrezeptoren alpha4beta7-Integrin und CCR10. Wahrscheinlich wandern sie in mukosale Plasmazelldepots ein und interferieren nicht mit den Plasmazellen des Knochenmarks, sodass die Stabilität des humoralen Gedächtnisses in der Ruhephase gewahrt bleibt. Eine Anpassung des humoralen Gedächtnisses findet somit nur im Rahmen systemischer Immunreaktionen statt. Bei splenektomierten Patienten und unter der B-Zell-Depletionstherapie bei Rheumapatienten bleiben mukosale Plasmablasten im Blut nachweisbar. Dies belegt deren autonome Bildung aus mukosalen, therapie-refraktären B-Zellen. Insgesamt wird hier eine bisher unbeachtete Komplexität menschlicher peripherer Plasmablasten und Plasmazellen und ihren Beziehungen zum humoralen Immungedächtnis dargestellt. / Humoral memory, i.e. persistence of specific antibody titers, is provided by plasma cells in the bone marrow, which are generated from activated B cells during immune responses. At this, immediate plasma cell precursors, the plasmablasts, migrate via the blood to the bone marrow. Using cytometric detection of antigen-specific plasmablasts, synchronous circulation of waves of recently generated, migratory plasmablasts and non migratory plasma cells with a mature phenotype was demonstrated one week after tetanus vaccination. Circulating plasmablast and plasma cell numbers were always in homeostasis, so that the stoichiometric mobilization of old bone marrow plasma cells by recently generated plasmablasts was hypothesized. This plasma cell replacement mechanism is herein described for the first time as an adaption mechanism of the humoral memory that allows incorporation of new antibody specificities while maintaining pre-existing ones. In immunological steady state, very low numbers of plasmablasts are detectable in any donor. These express IgA and receptors for mucosal homing, alpha4beta7 integrin and CCR10, and therefore most likely migrate into mucosal plasma cell depots and do not interfere with plasma cells of the bone marrow, preserving the stability of humoral memory during steady state. Hence, adaption of humoral memory is only possible during systemic immune reactions. Circulating mucosal plasmablasts produced during steady state remain detectable in patients with rheumatoid arthritis during B cell depletion therapy as well as in asplenic patients. Hence, this type of plasmablasts is self-sufficiently generated from mucosal B cells that are refractory to B cell depletion therapy. This work demonstrates a hitherto disregarded complexity of peripheral plasmablast and plasma cell subsets in healthy humans, with implications for the regulation of induction and maintenance of humoral memory.

Intimina é uma adesina de natureza protéica das bactérias diarreiogênicas Escherichia coli enteropatogenica (EPEC) e enterohemorrágica (EHEC), capazes de induzir a lesão \'attaching e effacing\' em enterócitos. Os principais subtipos de intiminas de EPEC e EHEC prevalentes no Brasil são α, β e γ. Nosso objetivo foi investigar a transferência de anticorpos maternos anti-intiminas aos recém-nascidos de mães saudáveis de São Paulo, Brasil. Foram pesquisados anticorpos SIgA no colostro e IgG no soro de 50 mulheres saudáveis e no soro de cordão umbilical de seus recém-nascidos, por ELISA utilizando como antígeno proteínas recombinantes purificadas das regiões conservadas e variáveis de intiminas α, β e γ. As concentrações de anticorpos no colostro foram superiores quando comparadas com as concentrações do soro para todos os tipos de intiminas. Não se observaram diferenças estatísticas entre as concentrações de anticorpos reativos com as diferentes intiminas nas amostras de colostro. As concentrações de anticorpos reativos com a região conservada da intimina foram significativamente mais elevadas em comparação com as regiões variáveis no soro dos grupos de mães e de recém-nascidos. Houve alta correlação entre todos os anticorpos anti-intiminas nas amostras de colostro. Comparando-se as concentrações de anticorpos séricos, os coeficientes foram maiores entre anti-α e anti-β que entre os outros pares. Nossos resultados confirmam a transferência de anticorpos maternos para o recém-nascido pela placenta e pelo aleitamento materno e reforça o efeito protetor da amamentação contra infecção por EPEC. / Intimin is a proteic adhesin of enteropatogenic (EPEC) and enterohemorragic (EHEC) Escherichia coli, capable of inducing attachment and effacement lesion in enterocytes. The main subtypes of intimins of EPEC and EHEC prevalent in Brazil are α, β and γ. Our aim is to investigate the transference of maternal anti-intimin antibodies to the newborns of healthy mothers from Sao Paulo, Brazil. IgG and SIgA antibodies were determined in sera and colostrum from 50 healthy women and cord sera from their newborns, by ELISA using as antigens purified recombinant proteins, conserved and variable regions of α, β and γ intimins. The IgA antibody concentrations of colostrum are higher than IgG antibodies in serum for all intimins and there were no statistical differences between them in colostrum samples. The concentrations of antibodies reactive with the conserved region of intimin are significantly higher compared to the variable regions in the sera groups, mothers and newborns. There were high correlation coefficients between all the anti-intimins antibodies in colostrum samples. In the comparison of the seric antibody concentrations, the coefficients were higher between anti-α and anti-β than all the other pairs. Our results confirm the transference of maternal antibodies to the newborns by placenta and breastfeeding and reinforce the high protection effect of breastfeeding against EPEC infection.

[ES] Antecedentes: Los patrones de colonización microbiana alterados durante la infancia pueden ser en parte responsables del aumento de enfermedades alérgicas en los países desarrollados. La microbiota intestinal difiere en composición y diversidad durante los primeros meses de vida en niños que luego desarrollan o no una enfermedad alérgica. Sin embargo, poco se sabe sobre la importancia de las respuestas inmunitarias tempranas de la mucosa a la microbiota intestinal en el desarrollo de alergias infantiles. Además, los estudios con respecto al efecto protector de la microbiota de la leche materna en el riesgo de desarrollar alergias no han sido concluyentes. Aunque la cavidad bucal es el primer lugar de encuentro entre la mayoría de los antígenos exógenos y el sistema inmunológico, no existen datos sobre la influencia de las bacterias orales en el desarrollo de alergias durante la infancia. Objetivos: El objetivo general de esta tesis fue evaluar la composición y diversidad microbiana en muestras orales, intestinales y de leche materna, junto con su interacción con IgA, para estudiar el papel de la colonización microbiana durante edades tempranas de la vida en condiciones de salud y de enfermedad alérgica. Sujetos: Los bebés y las madres incluidas en este estudio forman parte del ensayo aleatorio doble ciego más grande de Suecia, entre 2001 y 2003, donde se evaluaron los posibles efectos preventivos sobre la alergia de Lactobacillus reuteri ATCC 55730 hasta los 2 y 7 años. En esta tesis, utilizamos muestras de heces recogidas a los 1 y 12 meses, y muestras orales de bebés, obtenidas longitudinalmente a los 3, 6, 12, 24 meses y 7 años. Además, analizamos muestras de leche materna, recogidas a un mes después del parto de las madres correspondientes. Métodos: Se utilizaron tecnologías de secuenciación de segunda generación dirigidas al gen 16S rARN, en combinación con citometría de células marcadas por fluorescencia, para abordar las respuestas de IgA de la mucosa hacia las bacterias intestinales y de la leche materna. Además, se utilizó la secuenciación del gen 16S para describir la colonización oral de la microbiota, en muestras de saliva, de niños que desarrollaron alergias o de aquellos que se mantuvieron sanos. Los niveles de carga bacteriana en diferentes hábitats microbianos se obtuvieron mediante la metodología de qPCR y los niveles totales de IgA de las muestras de heces se determinaron mediante inmuno-ensayo ELISA. Resultados y conclusión: La colonización de la cavidad bucal durante la infancia temprana es progresiva, aumenta en complejidad con el tiempo, y varios factores externos parecen influir en gran medida en la maduración de la microbiota oral, ya sea con un impacto a corto o largo plazo. Los cambios tempranos en la composición microbiana oral parecen influir en la maduración inmune y el desarrollo de alergias en la infancia, y la presencia de especies bacterianas específicas puede ser importante para este proceso. Además, las respuestas de IgA alteradas hacia la microbiota intestinal durante la infancia precedieron a las manifestaciones de asma y alergia durante los primeros 7 años de vida, y el consumo de leche materna con una riqueza microbiana reducida en el primer mes de vida puede aumentar el riesgo de desarrollar alergia durante la infancia. Los hallazgos observados en la presente tesis deben confirmarse en cohortes más grandes y la importancia de los factores ambientales postnatales para el desarrollo temprano de la microbiota debe abordarse más a fondo. Las investigaciones futuras deben ir más allá de la caracterización de la composición de la comunidad bacteriana e investigar los mecanismos funcionales entre los microorganismos colonizadores tempranos, la maduración inmunitaria y la alergia, así como el desarrollo del asma durante la infancia. / [CAT] Antecedents: S'ha proposat que els patrons de colonització microbiana alterats durant la infància podrien ser en part els responsables de l'augment de malalties al·lèrgiques als països desenvolupats. La microbiota intestinal difereix en composició i diversitat durant els primers mesos de vida en els nens que després van desenvolupar una malaltia al·lèrgica. No obstant això, poc es sap sobre la importància de les respostes immunes de la mucosa a la microbiota intestinal en el desenvolupament d'al·lèrgies infantils. A més, les investigacions amb relació a l'efecte protector de la microbiota de la llet materna en el risc de desenvolupar al·lèrgies no han sigut concloents. Encara que la cavitat bucal és el primer lloc de trobada entre la majoria dels gèneres externs i el sistema immunològic, encara no s'ha descobert la influència dels bacteris en el desenvolupament d'una al·lèrgia durant la infància. Objectius: L'objectiu general d'aquesta tesi va ser avaluar la composició microbiana i la diversitat de mostres orals, fecals i llet materns, juntament amb la seva interacció amb IgA, per estudiar el paper del desenvolupament microbià durant el període de la infància primerenca a la salut i la malaltia al·lèrgica. Subjectes: Les mares i xiquets inclosos en aquest estudi formen part d'un estudi aleatori doble-cec a Suècia, entre el 2001 i el 2003, on es van avaluar els possibles efectes preventius de la suplementació amb Lactobacillus ATCC 55730 fins als 2 i 7 anys. En aquesta tesi, s'utilitzaren mostres de bebès arreplegades longitudinalment, obtinguts a 1 i 12 mesos, 3, 6, 12, 24 mesos i 7 anys, respectivament. A més, s'analitzaren les mostres de llet materna, arreplegades a un mes postpart de les corresponents mares. Mètodes: S'han utilitzat tecnologies de seqüenciació de nova generació dirigides al ARNr 16S, en combinació amb la classificació de les cèl·lules activades, per abordar les respostes de la mucosa cap als bacteris intestinals i de la llet materna. A més, s'utilitzà la seqüenciació d'Illumina MiSeq del gen 16S per descriure la colonització microbiana oral, i es van obtenir mostres longitudinals de saliva de menuts que varen desenvolupar al·lèrgies i d'alguns que es van mantenir saludables. Els nivells de càrrega bacteriana en diferents nínxols microbians s'han obtingut mitjançant la metodologia de qPCR i els nivells totals d'IgA de les mostres fecals es determinaren mitjançant l'immunoassaig ELISA. Resultats i conclusions: La colonització de la cavitat bucal durant la primera infància és transitòria, augmenta la seva complexitat amb el temps, i diversos factors externs influeixen en gran mesura el procés de maduració de la microbiota oral, amb un impacte a curt i llarg termini. Els canvis primerencs en la composició microbiana oral pareixen influir en la maduració del sistema immunològic i el desenvolupament d'al·lèrgies a la infància, així com la presència d'espècies bacterianes específiques pot ser important per a aquest progrés. A més, les respostes d'IgA alterades cap a la microbiota intestinal durant la infància precedeixen a les manifestacions relatives a la malaltia asmàtica i al·lèrgiques durant els primers 7 anys de vida. Per altra banda, el consum de llet materna amb una microbiota de riquesa reduïda al primer mes de vida podria augmentar el risc de desenvolupar al·lèrgia durant la infància. Els resultats observats en aquest estudi haurien de confirmar-se en cohorts humanes més grans i la importància dels factors ambientals post natals que influeixen en el desenvolupament de la microbiota primerenca han de ser més estudiats. Les investigacions futures deuen anar més enllà de la caracterització de la composició de la comunitat bacteriana i investigar els mecanismes funcionals entre els microorganismes colonitzadors primerencs, la maduració del sistema immunològic i el desenvolupament de l'al·lèrgia i l'asma durant la in / [EN] Background: It has been proposed that altered microbial colonization patterns during infancy may be partly responsible for the increase of allergic diseases in developed countries. The gut microbiota differs in composition and diversity during the first months of life in children who later do or do not develop allergic disease. However, little is known about the significance of early mucosal immune responses to the gut microbiota in childhood allergy development, and the findings regarding the protective effect of breastmilk microbiota in the risk of allergy development have been inconclusive. Furthermore, even though the oral cavity is the first site of encounter between a majority of foreign antigens and the immune system, the influence of oral bacteria on allergy development during childhood has not yet been reported. Objectives: The general aim of this thesis was to assess the microbial composition and diversity of oral, fecal and breastmilk samples, together with its interaction with IgA, in order to study the role of microbial development during early childhood in health and allergic disease. Subjects: The infants and mothers included in this study were part of a larger randomized double-blind trial in Sweden, between 2001 and 2003, where potential allergy preventive effects of Lactobacillus reuteri ATCC 55730 were evaluated until 2 and 7 years of age. In this thesis, we used longitudinally collected stool and oral samples from infants, obtained at 1 and 12 months and 3, 6, 12, 24 months and 7 years of age, respectively. Furthermore, we analyzed breastmilk samples, collected at one month post partum, from the corresponding mothers. Methods: Next-generation sequencing technologies targeting the 16S rRNA gene, in combination with cell activated cell sorting, were used in order to address mucosal IgA responses towards gut and breastmilk bacteria. Furthermore, sequencing of the 16S rRNA gene was used in order to describe oral microbiota colonization, in longitudinally obtained saliva samples, from children developing allergy or staying healthy. Bacterial load levels in different microbial habitats were obtained by qPCR methodology and total IgA levels of stool samples were determined by ELISA immunoassays. Results and conclusion: Colonization of the oral cavity during early childhood is transitional, increasing in complexity with time, and several external factors appear to greatly influence oral microbiota maturation, having either a short or a long-term impact. Early changes in oral microbial composition seem to influence immune maturation and allergy development in childhood, and the presence of specific bacterial species may be important for this progress. Furthermore, altered IgA responses towards the gut microbiota during infancy preceded asthma and allergy manifestations during the first 7 years of life, and consumption of breastmilk with a reduced microbial richness in the first month of life may increase the risk for allergy development during childhood. Findings observed here need to be confirmed in larger cohorts and the importance of postnatal environmental factors for early microbiota development should be addressed further. Future research should go beyond characterization of bacterial community composition and investigate the functional mechanisms between early colonizing microorganisms, immune maturation and allergy and asthma development during childhood. / Dzidic, M. (2019). Microbiota development and mucosal IgA responses during childhood in health and allergic disease [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/125479 / TESIS

O presente trabalho teve como objetivo o estudo da variabilidade genética e dos fatores de virulência de isolados de U. diversum. As cepas foram submetidas a sequenciamento dos genes da urease e 16S rRNA e a testes para verificar os fatores de virulência: cápsula, fosfolipase C, IgAse e adesão e invasão. A análise do sequênciamento parcial do gene 16S rRNA resultou na presença de polimorfismos em 44 posições da seqüência, que diferenciou as amostras em sete grupos. Em relação aos fatores de virulência, os dados mostraram que as cepas estudadas apresentaram uma camada densa ao redor da membrana celular dos microrganismos e atividade de fosfolipase C. No entanto, não foi observado a atividade de IgAse nas cepas. Em relação a atividade de invasão, observou-se que os ureaplasma estudados puderam ser visualizados no interior de células Hep-2 com apenas um minutos de infecção, sendo observados em uma região perinuclear, mas não no interior do núcleo. Além disto, pode verificar que entre 1% a 10% dos ureaplasmas estudos penetraram na célula pelo teste da gentamicina. / The aim of the present study was the study of genetic variability and virulence factors of U. diversum clinical isolates. The strains were submitted to sequencing for 16S rRNA and urease genes. Moreover, the strains were analyzed to the virulence factors: capsule, phospholipase C, IgA protease and adhesion and invasion into Hep-2 cells. The sequencing of parcial 16S rRNA gene showed polymorphic patterns into 44 positions. These polymorphisms clustered the strains in seven groups. For the virulence factors, ureaplasma cells showed a dense-stained external capsule-like structure surrounding the cell membrane. A high level of phospholipase C activity was also detected in 31 studied ureaplasma. However, no strains showed IgA protease activity. For the invasion assay, the isolates and strains used were detected inside the cells after infection of one minute. The invasions of the ureaplasmas surrounded the nuclear region but were not observed inside the nuclei. The gentamicin invasion assay detected that 1% to 10% of studied ureaplasmas were inside the infected cells.

No description available.

O presente trabalho teve como objetivo o estudo da variabilidade genética e dos fatores de virulência de isolados de U. diversum. As cepas foram submetidas a sequenciamento dos genes da urease e 16S rRNA e a testes para verificar os fatores de virulência: cápsula, fosfolipase C, IgAse e adesão e invasão. A análise do sequênciamento parcial do gene 16S rRNA resultou na presença de polimorfismos em 44 posições da seqüência, que diferenciou as amostras em sete grupos. Em relação aos fatores de virulência, os dados mostraram que as cepas estudadas apresentaram uma camada densa ao redor da membrana celular dos microrganismos e atividade de fosfolipase C. No entanto, não foi observado a atividade de IgAse nas cepas. Em relação a atividade de invasão, observou-se que os ureaplasma estudados puderam ser visualizados no interior de células Hep-2 com apenas um minutos de infecção, sendo observados em uma região perinuclear, mas não no interior do núcleo. Além disto, pode verificar que entre 1% a 10% dos ureaplasmas estudos penetraram na célula pelo teste da gentamicina. / The aim of the present study was the study of genetic variability and virulence factors of U. diversum clinical isolates. The strains were submitted to sequencing for 16S rRNA and urease genes. Moreover, the strains were analyzed to the virulence factors: capsule, phospholipase C, IgA protease and adhesion and invasion into Hep-2 cells. The sequencing of parcial 16S rRNA gene showed polymorphic patterns into 44 positions. These polymorphisms clustered the strains in seven groups. For the virulence factors, ureaplasma cells showed a dense-stained external capsule-like structure surrounding the cell membrane. A high level of phospholipase C activity was also detected in 31 studied ureaplasma. However, no strains showed IgA protease activity. For the invasion assay, the isolates and strains used were detected inside the cells after infection of one minute. The invasions of the ureaplasmas surrounded the nuclear region but were not observed inside the nuclei. The gentamicin invasion assay detected that 1% to 10% of studied ureaplasmas were inside the infected cells.

The series of experiments described in this thesis were designed to investigate the role of suckling or late weaning in the response of young lambs to nematode infection. All experiments were conducted outdoors with grazing animals and no supplementation but for suckled groups of lambs whose counterparts were weaned to ryegrass – white clover swards. The parasite of interest was mainly Teladorsagia circumcincta solely but with mixed infection of Trichostrongylus colubriformis in one instance. In Chapter 3 (first experiment), the hypothesis that milk per se may have a direct effect on nematode development, rather than an indirect effect through enhancement of host immunity by superior nutrient supply was tested. Sixty, twinborn lambs were used, allocated to one of eight groups formed by either dosing lambs from 42 days of age or not with the equivalent of 1000 or 250 L₃ T. circumcincta larvae d⁻¹ until five days before necropsy, while a twin was either weaned at 39 days of age, suckled as single or twin until necropsy on day 84. The possibility that weaning one of a twin set onto pasture in close proximity to the ewe would cause abnormal ewe and lamb behaviour was tested by replicating the work in twins maintained as twins but in which one twin received equivalent of 250 and the other 1000 L₃ T. circumcincta larvae d⁻¹. This showed no abnormal ewe nursing or lamb suckling behaviour as a result of weaning a twin in a set. Relatively low faecal egg counts (FEC) and a two to three fold lower worm burdens suggest suckling could reduce larval establishment. Inability to detect peripheral titres of immunoglobulins supports this conclusion. An intra worm-population regulation of T. circumcincta, indicated by a pattern of greater egg-laying by a numerically smaller but physiologically better developed nematode population in suckled lambs measured in eggs 'in utero' and worm length made interpretation of FEC difficult. Suckling significantly improved weight gain and carcass weights, but early weaning did not reduce resilience to infection. In Chapter 4 (second experiment), 40 pairs of twin lambs, average age of 39 days, were either infected with the equivalent of 1000 L₃ T. circumcincta larvae d⁻¹ or not, while one twin was weaned and the other allowed to continue suckling. Necropsy was carried out on groups of five and six lambs from each of the uninfected and infected treatments, respectively, at mean age of 84, 112, and on six lambs from each group at 140 days of age. This serial slaughter allowed further confirmation of the hypothesis in Chapter 3 but also investigated the long-term effect of suckling on resistance or resilience of lambs at the trial when immune responses were anticipated to be developing. An in vitro direct larval challenge (IVDC) study, to monitor larval establishment, was carried out on tissue explants from necropsied lambs. Suckled lambs consistently showed lower FEC (P < 0.05) and worm burdens (P < 0.05) at every phase of the trial. Within the infected groups, % in vitro larval rejection suggested earlier immune responses in the weaned lambs by day 84, which was not consistent with lower worm burdens in suckled lambs but appeared similar in the subsequent necropsies. Lambs continued to show better growth due to suckling while weaning did not reduce the resilience of lambs confirming observations in Chapter 3. The immunoglobulin profile suggested the commencement of immune responses in lambs from the period after the 84th day necropsy, with significantly greater (P < 0.01) IgA titre in the infected groups, and the suckled lambs towards the end of the trial on day 140. A vaccinating effect of early exposure to parasites was coincidentally revealed as a result of unintentional pasture larval contamination, seen in suckled non-infected lambs shedding fewer eggs and harbouring fewer worms during the later necropsies compared with their weaned non-infected counterparts. In Chapter 5 (third trial), 93 pairs of twin lambs, 47 pairs of which received a vaccinating mixed infection of T. circumcincta and T. colubriformis larvae (60 L₃ / kg W / d) at ratio 40:60, respectively during the period 36 – 103 days of age, were either weaned early on day 51 or later on day 108. All lambs were drenched on day 108 and groups received challenge infections from day 116, at same rate with the vaccinating infection, or not, which ceased five days before respective necropsies. Necropsies were carried out on selected lambs on days 108, 184 and 218. The direct effect of milk on larval establishment appeared to feature only in the T. circumcincta populations on slaughter day 108. The long-term benefit of late weaning for development of resistance was conditional on lambs receiving the vaccinating infection, and appeared to be more pronounced in the small intestine, reflected by a greater reduction of T. colubriformis populations in that organ than of T. circumcincta populations in the abomasum. A negative consequence of enhanced immune response was the suggestion of an increased metabolic cost in reduced performance of lambs. In conclusion, the work provides support to the hypotheses that: (a.) suckling may reduce the establishment of nematode larvae through the direct effect of milk, (b.) may enhance rapid development of host immunity to infection, and (c.) it further suggests that lack of larval experience during suckling may have long term negative implications for host resistance. Finally, it suggests that milk may play little role in the enhancement of host resilience to infection and, on the contrary, that additional metabolic cost may be associated with a more rapid development of immunity resulting from larval challenge while suckling.

The author addresses a broad overview of the significant role played by all those new developments and trends in science, technology and innovation (STI), which are applied to the environmental management of mining projects. It also examines the new provisions introduced by the D.S. No. 054-2013-PCM and D.S. No. 060-2013-PCM, as well as their complementary regulations (specifically, those of environmental relevance for the mining sector), in the context of policies aimed at stimulating the economy and promoting private investment that are being implemented by the Government. In addition, the article focuses on different practical situations and evaluates the relevant environmental implications that mining companies usually face when redesigning or modifying the components of their projects. Finally, analyzes the criteria of the Ministry of Energy and Mines concerning the rules on environmental management instruments for the mining industry, and the new regime applicable for amending these instruments, as well as the aspects, scope and measures that are being adopted and discussed with regards to the obligation of updating the approved environmental impact studies. / El autor muestra un panorama amplio del significativo papel que desempeñan los nuevos desarrollos en ciencia, tecnología e innovación (CTI) aplicados a la gestión ambiental de los proyectos mineros. Asimismo, analiza las nuevas disposiciones introducidas por los D.S. No. 054-2013-PCM y 060-2013-PCM, así como sus normas complementarias (específicamente, aquellas de relevancia ambiental para el sector minero), en el marco de las políticas de reactivación económica  y  promoción  de  la  inversión  privada  que  viene  implementando el Gobierno. Además, plantea distintas situaciones prácticas y evalúa las respectivas implicancias ambientales que, muchas veces, las empresas mineras afrontan al momento de rediseñar o modificar los componentes de sus proyectos. Por último, analiza los criterios del Ministerio de Energía y Minas respecto de la normativa en materia de los instrumentos de gestión ambiental en el sector minero (IGA) y del nuevo régimen aplicable a la modificación de los IGA, así como los aspectos, alcances y medidas que se vienen adoptando y discutiendo con relación a la obligación de actualizar los estudios ambientales aprobados.