Browsing by Author "Alenquer, Marta"
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- Balance between maternal antiviral response and placental transfer of protection in gestational SARS-CoV-2 infectionPublication . Gonçalves, Juliana; Melro, Magda; Alenquer, Marta; Araújo, Catarina; Castro-Neves, Júlia; Amaral-Silva, Daniela; Ferreira, Filipe; Ramalho, José S.; Charepe, Nádia; Serrano, Fátima; Pontinha, Carlos; Amorim, Maria João; Soares, HelenaThe intricate interplay between maternal immune response to SARS-CoV-2 and the transfer of protective factors to the fetus remains unclear. By analyzing mother-neonate dyads from second and third trimester SARS-CoV-2 infections, our study shows that neutralizing antibodies (NAbs) are infrequently detected in cord blood. We uncovered that this is due to impaired IgG-NAb placental transfer in symptomatic infection and to the predominance of maternal SARS-CoV-2 NAbs of the IgA and IgM isotypes, which are prevented from crossing the placenta. Crucially, the balance between maternal antiviral response and transplacental transfer of IgG-NAbs appears to hinge on IL-6 and IL-10 produced in response to SARS-CoV-2 infection. In addition, asymptomatic maternal infection was associated with expansion of anti-SARS-CoV-2 IgM and NK cell frequency. Our findings identify a protective role for IgA/IgM-NAbs in gestational SARS-CoV-2 infection and open the possibility that the maternal immune response to SARS-CoV-2 infection might benefit the neonate in 2 ways, first by skewing maternal immune response toward immediate viral clearance, and second by endowing the neonate with protective mechanisms to curtail horizontal viral transmission in the critical postnatal period, via the priming of IgA/IgM-NAbs to be transferred by the breast milk and via NK cell expansion in the neonate.
- Challenges in imaging analyses of biomolecular condensates in cells infected with influenza A virusPublication . Etibor, Temitope Akhigbe; O’Riain, Aidan; Alenquer, Marta; Diwo, Christian; Vale-Costa, Sílvia; Amorim, Maria JoãoBiomolecular condensates are crucial compartments within cells, relying on their material properties for function. They form and persist through weak, transient interactions, often undetectable by classical biochemical approaches. Hence, microscopy-based techniques have been the most reliable methods to detail the molecular mechanisms controlling their formation, material properties, and alterations, including dissolution or phase transitions due to cellular manipulation and disease, and to search for novel therapeutic strategies targeting biomolecular condensates. However, technical challenges in microscopy-based analysis persist. This paper discusses imaging, data acquisition, and analytical methodologies’ advantages, challenges, and limitations in determining biophysical parameters explaining biomolecular condensate formation, dissolution, and phase transitions. In addition, we mention how machine learning is increasingly important for efficient image analysis, teaching programs what a condensate should resemble, aiding in the correlation and interpretation of information from diverse data sources. Influenza A virus forms liquid viral inclusions in the infected cell cytosol that serve as model biomolecular condensates for this study. Our previous work showcased the possibility of hardening these liquid inclusions, potentially leading to novel antiviral strategies. This was established using a framework involving live cell imaging to measure dynamics, internal rearrangement capacity, coalescence, and relaxation time. Additionally, we integrated thermodynamic characteristics by analysing fixed images through Z-projections. The aforementioned paper laid the foundation for this subsequent technical paper, which explores how different modalities in data acquisition and processing impact the robustness of results to detect bona fide phase transitions by measuring thermodynamic traits in fixed cells. Using solely this approach would greatly simplify screening pipelines. For this, we tested how single focal plane images, Z-projections, or volumetric analyses of images stained with antibodies or live tagged proteins altered the quantification of thermodynamic measurements. Customizing methodologies for different biomolecular condensates through advanced bioimaging significantly contributes to biological research and potential therapeutic advancements.
- Defining basic rules for hardening influenza A virus liquid condensatesPublication . Etibor, Temitope Akhigbe; Vale-Costa, Silvia; Sridharan, Sindhuja; Brás, Daniela; Becher, Isabelle; Mello, Victor Hugo; Ferreira, Filipe; Alenquer, Marta; Savitski, Mikhail M; Amorim, Maria-JoãoIn biological systems, liquid and solid-like biomolecular condensates may contain the same molecules but their behaviour, including movement, elasticity and viscosity, is different on account of distinct physicochemical properties. As such, it is known that phase transitions affect the function of biological condensates and that material properties can be tuned by several factors including temperature, concentration and valency. It is, however, unclear if some factors are more efficient than others at regulating their behaviour. Viral infections are good systems to address this question as they form condensates de novo as part of their replication programmes. Here, we used influenza A virus liquid cytosolic condensates, A.K.A viral inclusions, to provide a proof of concept that liquid condensate hardening via changes in the valency of its components is more efficient than altering their concentration or the temperature of the cell. Liquid IAV inclusions may be hardened by targeting vRNP interactions via the known NP oligomerizing molecule, nucleozin, both in vitro and in vivo without affecting host proteome abundance nor solubility. This study is a starting point for understanding how to pharmacologically modulate the material properties of IAV inclusions and may offer opportunities for alternative antiviral strategies.
- Pre-existing IgG antibodies to HCoVs NL63 and OC43 spike increased during the pandemic and after COVID-19 vaccinationPublication . Hasan, Zahra; Masood, Kiran Iqbal; Veldhoen, Marc; Qaiser, Shama; Alenquer, Marta; Akhtar, Mishgan; Balouch, Sadaf; Iqbal, Junaid; Wassan, Yaqub; Hussain, Shahneel; Feroz, Khalid; Muhammad, Sajid; Habib, Atif; Kanji, Akbar; Khan, Erum; Mian, Afsar Ali; Hussain, Rabia; Amorim, Maria Joao; Bhutta, Zulfiqar A.Preexisting immunity may be associated with increased protection against non-related pathogens such as, SARS-CoV-2. There is little information regarding endemic human coronaviruses (HCOVs) from Pakistan, which experienced a relatively low COVID-19 morbidity and mortality. We investigated antibodies to SARS-CoV-2 and HCoVs NL63 and OC43, comparing sera from prepandemic controls (PPC) period with responses in healthy controls from the pandemic (HC 2021). Further, we investigated the effect of inactivated and mRNA COVID-19 vaccinations on antibody responses to the pandemic and endemic coronaviruses. We measured IgG antibodies to Spike of SARS-CoV-2, HCoV-NL63 and HCoV-OC43 by ELISA. Serum neutralizing capacity was determined using a SARS-CoV-2 psuedotyped virus assay. Vaccinees were sampled prior to vaccination as well after 6, 12 and 24 weeks after COVID-19 inactivated (Sinovac), or mRNA (BNT162b2) vaccine administration. PPC sera showed seropositivity of 15 % to SARS-CoV-2, whilst it was 45 % in the HC 2021 group. Five percent of sera showed virus neutralizing activity in PPC whilst it was 50 % in HC 2021. IgG antibodies to Spike of NL63 and OC43 were also present in PPC; anti-NL63 was 2.9-fold, and anti-OC43 was 10.1-fold higher than to anti-SARS-CoV-2 levels. IgG antibodies to Spike SARS-CoV-2 were positively correlated with HCoV-NL63 in HC 2021, indicating recognition of shared conserved epitopes. IgG antibody levels increased during the pandemic; 2.7-fold to HCoV-NL63 and 1.9-fold to HCoV-OC43. SinoVac and BNT162b2 vaccine induced an increase in IgG antibodies to Spike SARS-CoV-2 as well as HCoV-NL63 and HCoV-OC43. Our data show that antibodies to spike protein of endemic coronaviruses were present in the prepandemic population. Antibodies to SARS-CoV-2, NL63 and OC43 were all raised during the pandemic and further enhanced after COVID-19 vaccinations. The increase in antibodies to spike of coronaviruses would contribute to protection against SARS-CoV-2.