Malaria and tuberculosis co-infection:role for hemozoin immunosuppression?

Tese de doutoramento, Ciências Biomédicas (Microbiologia e Parasitologia), Universidade de Lisboa, Faculdade de Medicina, 2014

Avaliação do estatuto de conservação da flora endémica de Cabo Verde

Tese de mestrado. Biologia (Ecologia e Gestão Ambiental). Universidade de Lisboa, Faculdade de Ciências, 2014

A Community-Level, Mesoscale Analysis of Fish Assemblage Structure in Shoreline Habitats of a Large River Using Multivariate Regression Trees.

The mesoscale (100–102 m) of river habitats has been identified as the scale that simultaneously offers insights into ecological structure and falls within the practical bounds of river management. Mesoscale habitat (mesohabitat) classifications for relatively large rivers, however, are underdeveloped compared with those produced for smaller streams. Approaches to habitat modelling have traditionally focused on individual species or proceeded on a species-by-species basis. This is particularly problematic in larger rivers where the effects of biological interactions are more complex and intense. Community-level approaches can rapidly model many species simultaneously, thereby integrating the effects of biological interactions while providing information on the relative importance of environmental variables in structuring the community. One such community-level approach, multivariate regression trees, was applied in order to determine the relative influences of abiotic factors on fish assemblages within shoreline mesohabitats of San Pedro River, Chile, and to define reference communities prior to the planned construction of a hydroelectric power plant. Flow depth, bank materials and the availability of riparian and instream cover, including woody debris, were the main variables driving differences between the assemblages. Species strongly indicative of distinctive mesohabitat types included the endemic Galaxias platei. Among other outcomes, the results provide information on the impact of non-native salmonids on river-dwelling Galaxias platei, suggesting a degree of habitat segregation between these taxa based on flow depth. The results support the use of the mesohabitat concept in large, relatively pristine river systems, and they represent a basis for assessing the impact of any future hydroelectric power plant construction and operation. By combing community classifications with simple sets of environmental rules, the multivariate regression trees produced can be used to predict the community structure of any mesohabitat along the reach.

The Activity of Breast Milk and Monoclonal HIV-specific Antibodies in Mother-to-Child Transmission

Mother-to-child transmission of HIV is a unique setting that allows us to explore both the correlates of protective immunity and the characteristics of transmitted variants. This thesis first describes the levels and functional capacity of breast milk HIV-specific antibodies in 19 women with high plasma viral loads. Neutralizing antibodies (Nabs) were detected in breast milk supernatant (BMS) of 4 of 19 women examined, were of low potency and were not associated with infant infection. The low NAb activity in BMS was reflected in binding antibody levels with HIV envelope specific IgG titers being 2.2 log10 lower in BMS versus plasma. In contrast, non- neutralizing antibodies (nNAbs) capable of antibody dependent cell-mediated cytotoxicity (ADCC) were detected in the BMS from all 19 women. BMS ADCC activity was associated with envelope-specific IgG titers (p = 0.014) and was inversely associated with infant infection risk (p = 0.039). Our data indicate that BMS has limited HIV neutralizing activity, however, BMS ADCC activity is a correlate of transmission that may impact infant infection risk. In the second part of this thesis the neutralization sensitivity of 111 variants of diverse subtypes obtained from mothers and infants was determined against 7 HIVspecific broadly neutralizing monoclonal antibodies (mAbs) (NIH45-46w, VRC01, PGT128, PGT121, PG9 PGT145 and b12). Maternal and infant variants did not differ in their neutralization sensitivity to these mAbs and neither did variants from transmitting versus those from non-transmitting women. However, subtype A viruses were iii significantly more sensitive to neutralization by NIH45-46w and VRC01 (p= 0.0001 in both cases) and PGT145 (p=0.03) compared to non-subtype A viruses. Together, NIH45- 46w and PGT128 neutralization profiles resulted in 100% coverage of the variants tested. These data suggest that the epitopes targeted by these mAbs are present and accessible in both circulating and transmitted variants and that a combination of antibodies would provide maximum coverage against diverse subtypes commonly found in HIV endemic regions. Overall, this data suggest that an antibody based HIV vaccine capable of eliciting antibodies of multiple specificities that can mediate ADCC and/or neutralizing activity can provide protection and conquer the genetic diversity displayed by HIV.

Plano de gestão e conservação de Azorina vidalii (Wats.) Feer

Dissertação de Mestrado, Gestão e Conservação da Natureza, 15 de Maio de 2015, Universidade dos Açores.

Estudo morfológico e filogenético das subespécies Daucus carota ssp. Azoricus e Daucus carota ssp. Maritimus na ilha de S. Miguel

Dissertação de Mestrado, Biodiversidade e Biotecnologia Vegetal, 17 de Março de 2015, Universidade dos Açores.

Biodiversidade da Reserva Florestal de Recreio do Pinhal da Paz

Dissertação de Mestrado, Biodiversidade e Biotecnologia Vegetal, 4 de Fevereiro de 2016, Universidade dos Açores.

Mathematical model for HIV dynamics in HIV-specific helper cells

In this paper we study a delay mathematical model for the dynamics of HIV in HIV-specific CD4 + T helper cells. We modify the model presented by Roy and Wodarz in 2012, where the HIV dynamics is studied, considering a single CD4 + T cell population. Non-specific helper cells are included as alternative target cell population, to account for macrophages and dendritic cells. In this paper, we include two types of delay: (1) a latent period between the time target cells are contacted by the virus particles and the time the virions enter the cells and; (2) virus production period for new virions to be produced within and released from the infected cells. We compute the reproduction number of the model, R0, and the local stability of the disease free equilibrium and of the endemic equilibrium. We find that for values of R0<1, the model approaches asymptotically the disease free equilibrium. For values of R0>1, the model approximates asymptotically the endemic equilibrium. We observe numerically the phenomenon of backward bifurcation for values of R0⪅1. This statement will be proved in future work. We also vary the values of the latent period and the production period of infected cells and free virus. We conclude that increasing these values translates in a decrease of the reproduction number. Thus, a good strategy to control the HIV virus should focus on drugs to prolong the latent period and/or slow down the virus production. These results suggest that the model is mathematically and epidemiologically well-posed.

A coinfection model for HIV and HCV

We study a mathematical model for the human immunodeficiency virus (HIV) and hepatites C virus (HCV) coinfection. The model predicts four distinct equilibria: the disease free, the HIV endemic, the HCV endemic, and the full endemic equilibria. The local and global stability of the disease free equilibrium was calculated for the full model and the HIV and HCV submodels. We present numerical simulations of the full model where the distinct equilibria can be observed. We show simulations of the qualitative changes of the dynamical behavior of the full model for variation of relevant parameters. From the results of the model, we infer possible measures that could be implemented in order to reduce the number of infected individuals.

Seroprevalência da Brucelose nos últimos cinco anos na Unidade Local de Saúde do Alto-Minho

A brucelose é uma zoonose com elevada importância, causada por bactérias gram-negativas que são altamente patogénicas para uma grande variedade de animais e humanos. Existem zonas endémicas onde esta se prolifera com mais facilidade. Neste estudo os dados são relativos ao distrito de Viana do Castelo, os dados são recolhidas da base de dados da Unidade Local de Saúde do Alto-Minho, uma zona não considerada endémica. Os animais infetados são a principal fonte de contaminação e dispersão da brucelose, é necessário uma reduzida carga bacteriana para ocorrer a infeção. Trata-se de uma doença que está longe de ser erradicada, impondo-se tomar medidas preventivas em relação à contaminação. Os testes usados na sua deteção podem ser alterados e melhorados de acordo com o estádio da doença. Na ULSAM são usados o teste de Wright e eventualmente a pesquisa microbiológica da bactéria Brucella. É pertinente saber o número de testes positivos que ocorrem por ano, se existe alguma sazonalidade relacionada com a doença, assim como, relacionar os parâmetros bioquímicos com um teste de Wright positivo. Os dados foram recolhidos entre o ano 2009-2013 com um número total de testes de 1035, dos quais o número total de positivos para o teste são 102, mas apenas trinta são positivos com significância. Os dados foram recolhidos através do programa Clinidata utilizado como base de armazenamento de dados da ULSAM e foram tratados estatisticamente com o programa SPSS juntamente com o Excel. Este estudo permitiu concluir que o número de casos em 2009 e 2010 era superior aos restantes anos, o que descreve uma tendência para diminuição do número de casos de brucelose atualmente no distrito de Viana do Castelo. Em relação a sazonalidade, os meses que apresentam uma percentagem superior a 50% em relação seroprevalência são os meses de Junho, Novembro e Dezembro. Os resultados revelam como declarado pela Organização Mundial de Saúde que o Distrito de Viana do Castelo não é uma zona endémica. Através da análise estatística foi possível concluir que um dos parâmetros bioquímicos, neste caso o número de leucócitos, poderá estar diretamente relacionado com um teste de Wright positivo, uma vez que, 37% da amostra de testes positivos revelam leucopenia.

Monomeric and oligomeric flavan-3-ols and antioxidant activity of leaves from different Laurus sp.

The phenolic profile and antioxidant activity of three endemic Laurus sp. from Portugal were analysed. Dried leaves of L. nobilis L., L. azorica (Seub.) Franco, and L. novocanariensis Rivas Mart., Lousã, Fern. Prieto, E. Días, J. C. Costa & C. Aguiar, collected in the mainland and in the Azores and Madeira archipelagos, respectively, were used to prepare different extracts (aqueous, ethanolic and hydroalcoholic). They were studied regarding their DPPH˙ scavenging activity, total phenolic and flavonoid contents, and the main phenolic compounds were identified by HPLC-DAD-ESI-MS/MS. Total flavonoid contents were 30.1, 46.3, and 36.7 mg of epicatechin equivalents per g of sample (dry weight) for L. nobilis, L. azorica and L. novocanariensis, respectively. Epicatechin was the major compound, representing ∼12.1% of total flavan-3-ols in L. nobilis, ∼25.6% in L. azorica, and ∼19.9% in L. novocanariensis. Although all samples presented a similar phenolic profile, significant differences were observed in their total contents and antioxidant activity.

Effects of treatment, awareness and condom use in a coinfection model for HIV and HCV in MSM

We develop a new a coinfection model for hepatitis C virus (HCV) and the human immunodeficiency virus (HIV). We consider treatment for both diseases, screening, unawareness and awareness of HIV infection, and the use of condoms. We study the local stability of the disease-free equilibria for the full model and for the two submodels (HCV only and HIV only submodels). We sketch bifurcation diagrams for different parameters, such as the probabilities that a contact will result in a HIV or an HCV infection. We present numerical simulations of the full model where the HIV, HCV and double endemic equilibria can be observed. We also show numerically the qualitative changes of the dynamical behavior of the full model for variation of relevant parameters. We extrapolate the results from the model for actual measures that could be implemented in order to reduce the number of infected individuals.

Unraveling maternal and fetal genetic factors protecting from Pregnancy Associated Malaria in the mouse

Malaria is one of the most devastating diseases in the world. In Plasmodium endemic regions, pregnant women are among the most vulnerable groups. Pregnancy Associated Malaria (PAM) threatens both maternal and foetal lives. Despite differences between human and mouse placentas PAM mouse models recapitulate key pathological features of human PAM. Here we describe new PAM models of mid gestation infection in the C57BL/6 mouse.(...)

Safety and immunogenicity of the M72/AS01 candidate tuberculosis vaccine in HIV-infected adults on combination antiretroviral therapy: a phase I/II, randomized trial.

OBJECTIVE: Tuberculosis (TB) is highly prevalent among HIV-infected people, including those receiving combination antiretroviral therapy (cART), necessitating a well tolerated and efficacious TB vaccine for these populations. We evaluated the safety and immunogenicity of the candidate TB vaccine M72/AS01 in adults with well controlled HIV infection on cART. DESIGN: A randomized, observer-blind, controlled trial (NCT00707967). METHODS: HIV-infected adults on cART in Switzerland were randomized 3 : 1 : 1 to receive two doses, 1 month apart, of M72/AS01, AS01 or 0.9% physiological saline (N = 22, N = 8 and N = 7, respectively) and were followed up to 6 months postdose 2 (D210). Individuals with CD4⁺ cell counts below 200 cells/μl were excluded. Adverse events (AEs) including HIV-specific and laboratory safety parameters were recorded. Cell-mediated (ICS) and humoral (ELISA) responses were evaluated before vaccination, 1 month after each dose (D30, D60) and D210. RESULTS: Thirty-seven individuals [interquartile range (IQR) CD4⁺ cell counts at screening: 438-872 cells/μl; undetectable HIV-1 viremia] were enrolled; 73% of individuals reported previous BCG vaccination, 97.3% tested negative for the QuantiFERON-TB assay. For M72/AS01 recipients, no vaccine-related serious AEs or cART-regimen adjustments were recorded, and there were no clinically relevant effects on laboratory safety parameters, HIV-1 viral loads or CD4⁺ cell counts. M72/AS01 was immunogenic, inducing persistent and polyfunctional M72-specific CD4⁺ T-cell responses [medians 0.70% (IQR 0.37-1.07) at D60] and 0.42% (0.24-0.61) at D210, predominantly CD40L⁺IL-2⁺TNF-α⁺, CD40L⁺IL-2⁺ and CD40L⁺IL-2⁺TNF-α⁺IFN-γ⁺]. All M72/AS01 vaccines were seropositive for anti-M72 IgG after second vaccination until study end. CONCLUSION: M72/AS01 was clinically well tolerated and immunogenic in this population, supporting further clinical evaluation in HIV-infected individuals in TB-endemic settings.

Sympatric speciation in palms on an oceanic island.

The origin of species diversity has challenged biologists for over two centuries. Allopatric speciation, the divergence of species resulting from geographical isolation, is well documented. However, sympatric speciation, divergence without geographical isolation, is highly controversial. Claims of sympatric speciation must demonstrate species sympatry, sister relationships, reproductive isolation, and that an earlier allopatric phase is highly unlikely. Here we provide clear support for sympatric speciation in a case study of two species of palm (Arecaceae) on an oceanic island. A large dated phylogenetic tree shows that the two species of Howea, endemic to the remote Lord Howe Island, are sister taxa and diverged from each other well after the island was formed 6.9 million years ago. During fieldwork, we found a substantial disjunction in flowering time that is correlated with soil preference. In addition, a genome scan indicates that few genetic loci are more divergent between the two species than expected under neutrality, a finding consistent with models of sympatric speciation involving disruptive/divergent selection. This case study of sympatric speciation in plants provides an opportunity for refining theoretical models on the origin of species, and new impetus for exploring putative plant and animal examples on oceanic islands.