My research group is working to improve our understanding how the molecular interactions of dengue virus and other flaviviruses with their mosquito vectors contribute to the transmission and global emergence of these viruses. I am passionate about using science to improve health and wellbeing in the real world. I sit on the Microbiology Society policy committee, and have organised training workshops in Indonesia. I am a founding member of the University of Surrey Neglected Tropical Diseases Hub (@NTDhub), an interdisciplinary network bringing together biomedical and social scientists with engineers to solve the biggest challenges in neglected tropical diseases globally. I am also a co-organiser of the Recently Independent Virology Researchers network in the UK. I have developed teaching material for underprivileged youths in New York City, and contributed to programme development at the BBC. My research has been funded by the Wellcome Trust, Medical Research Council, and the Global Challenges Research Fund.
Previously, I studied herpesvirus assembly for my PhD thesis in the lab of Professor Gill Elliott at Imperial College London (London, UK), after graduating with degree in Medical Microbiology and Virology from the University of Warwick (Coventry, UK). I was then funded by the Wellcome Trust to study the molecular interactions between dengue virus and its human host and mosquito vector on a postdoctoral fellowship split between the labs of Professor Ana Fernandez-Sesma (Icahn School of Medicine at Mount Sinai, New York, USA) and Dr. Andrew Davidson (University of Bristol, UK).
Areas of specialism
University roles and responsibilities
- Senior Professional Training Year Tutor (International)
Affiliations and memberships
The Maringer Lab is working to understand the fundamental processes that determine how mosquito-borne viruses are transmitted between humans, alongside studies into the mechanisms that drive the global emergence and spread of new mosquito-borne diseases. We are most interested in the flavivirus dengue virus, which is the most significant arthropod-borne virus (arbovirus) affecting humans, with an estimated 400 million infections across the globe each year. We are also studying the related Zika virus to understand how this virus emerged so rapidly across the Americas. Our research focuses on the mosquito species Aedes aegypti (the 'yellow fever mosquito') and Aedes albopictus (the 'Asian tiger mosquito'), which are distributed globally across the tropics and subtropics and are vectors for dengue virus and Zika virus as well as other important arboviruses that infect humans (for example yellow fever virus and chikungunya virus). Because many mosquito-borne viruses lack effective vaccines or antiviral therapies, targeting their mosquito vectors remains one of our most important strategies for preventing human disease.
Our approach is to use cutting-edge 'omics' technologies to profile global responses of mosquito cells to viral infection. For example, we use 'proteomics' methods to measure every protein in a given sample, which can tell us how mosquito cells respond when infected with dengue or Zika virus (e.g. does the immune system activate?), and whether these viruses alter the cellular environment for their own benefit (e.g. do they steal the cell's nutrients?). We follow up on the big data sets generated using gene editing technologies (CRISPR-Cas9) and molecular tools developed in our lab. By comparing related and unrelated arboviruses in this way, we can pinpoint virus-specific and broadly-applicable molecular mechanisms that drive the transmission, emergence and global spread of flaviviruses like dengue virus and Zika virus. This information will facilitate the development of vector-targeted interventions to reduce the global burden of arboviral disease.
If you are a prospective student or postdoc interested in joining our research group, please get in touch. We welcome ERASMUS students, please get in touch if you are interested in our research.
We are working with Dr. Paola Campagnolo (School of Bioscience and Medicine) to study how dengue virus causes vascular leakage in haemorrhagic fever patients.
We are collaborating with Dr. Andrew Davidson and Dr. David Matthews (both University of Bristol, UK) to develop new bioinformatic methods to study the proteomes and transcriptomes of mosquito vectors of human disease.
We are collaborating with Dr. Rennos Fragkoudis (Pirbright Institute) and Professor Andres Merits (Institute of Technology, University of Tartu, Estonia) to study molecular drivers of arbovirus emergence in mosquitoes.
Courses I teach on
tegument proteins are recruited by the cytoplasmic tails of viral glycoproteins. In the case of herpes simplex
virus tegument protein VP22, interactions with the glycoproteins gE and gD have been shown. We have
previously shown that the C-terminal half of VP22 contains the necessary signal for assembly into the virus.
Here, we show that during infection VP22 interacts with gE and gM, as well as its tegument partner VP16.
However, by using a range of techniques we were unable to demonstrate VP22 binding to gD. By using pulldown
assays, we show that while the cytoplasmic tails of both gE and gM interact with VP22, only gE interacts
efficiently with the C-terminal packaging domain of VP22. Furthermore, gE but not gM can recruit VP22 to the
Golgi/trans-Golgi network region of the cell in the absence of other virus proteins. To examine the role of the
gE-VP22 interaction in infection, we constructed a recombinant virus expressing a mutant VP22 protein with
a 14-residue deletion that is unable to bind gE ( gEbind). Coimmunoprecipitation assays confirmed that this
variant of VP22 was unable to complex with gE. Moreover, VP22 was no longer recruited to its characteristic
cytoplasmic trafficking complexes but exhibited a diffuse localization. Importantly, packaging of this variant
into virions was abrogated. The mutant virus exhibited poor growth in epithelial cells, similar to the defect we
have observed for a VP22 knockout virus. These results suggest that deletion of just 14 residues from the VP22
protein is sufficient to inhibit binding to gE and hence recruitment to the viral envelope and assembly into the
virus, resulting in a growth phenotype equivalent to that produced by deleting the entire reading frame.
immune response. To efficiently infect humans, DENV must evade or inhibit fundamental elements of the innate immune
system, namely the type I interferon response. DENV circumvents the host immune response by expressing proteins that
antagonize the cellular innate immunity. We have recently documented the inhibition of type I IFN production by the
proteolytic activity of DENV NS2B3 protease complex in human monocyte derived dendritic cells (MDDCs). In the present
report we identify the human adaptor molecule STING as a target of the NS2B3 protease complex. We characterize the
mechanism of inhibition of type I IFN production in primary human MDDCs by this viral factor. Using different human and
mouse primary cells lacking STING, we show enhanced DENV replication. Conversely, mutated versions of STING that cannot
be cleaved by the DENV NS2B3 protease induced higher levels of type I IFN after infection with DENV. Additionally, we show
that DENV NS2B3 is not able to degrade the mouse version of STING, a phenomenon that severely restricts the replication of
DENV in mouse cells, suggesting that STING plays a key role in the inhibition of DENV infection and spread in mice.
4 DENV serotypes, epidemiological data suggest that DENV-2 secondary infections are associated
with more severe disease than DENV-4 infections. Mass cytometry by time-of-flight (CyTOF)
was used to dissect immune changes induced by DENV-2 and DENV-4 in human DCs, the initial
targets of primary infections that likely affect infection outcomes. Strikingly, DENV-4 replication
peaked earlier and promoted stronger innate immune responses, with increased expression of DC
activation and migration markers and increased cytokine production, compared with DENV-2. In
addition, infected DCs produced higher levels of inflammatory cytokines compared with bystander
DCs, which mainly produced IFN-induced cytokines. These high-dimensional analyses during
DENV-2 and DENV-4 infections revealed distinct viral signatures marked by different replication
strategies and antiviral innate immune induction in DCs, which may result in different viral fitness,
transmission, and pathogenesis.
specific differences in virus pathogenesis and
host inflammatory immune responses,PLoS Pathogens 13 (3) e1006258 Pubic Library of Science
until it emerged and spread across the Pacific Area and the Americas, causing large human
outbreaks associated with fetal abnormalities and neurological disease in adults. The factors
that contributed to the emergence, spread and change in pathogenesis of ZIKV are not
understood. We previously reported that ZIKV evades cellular antiviral responses by targeting
STAT2 for degradation in human cells. In this study, we demonstrate that Stat2-/- mice
are highly susceptible to ZIKV infection, recapitulate virus spread to the central nervous system
(CNS), gonads and other visceral organs, and display neurological symptoms. Further,
we exploit this model to compare ZIKV pathogenesis caused by a panel of ZIKV strains of a
range of spatiotemporal history of isolation and representing African and Asian lineages.
We observed that African ZIKV strains induce short episodes of severe neurological symptoms
followed by lethality. In comparison, Asian strains manifest prolonged signs of neuronal
malfunctions, occasionally causing death of the Stat2-/- mice. African ZIKV strains
induced higher levels of inflammatory cytokines and markers associated with cellular infiltration
in the infected brain in mice, which may explain exacerbated pathogenesis in comparison
to those of the Asian lineage. Interestingly, viral RNA levels in different organs did not
correlate with the pathogenicity of the different strains. Taken together, we have established
a new murine model that supports ZIKV infection and demonstrate its utility in highlighting
intrinsic differences in the inflammatory response induced by different ZIKV strains leading
to severity of disease. This study paves the way for the future interrogation of strain-specific
changes in the ZIKV genome and their contribution to viral pathogenesis.
Dengue virus (DENV) is the most significant arthropod-borne virus (arbovirus) of humans, primarily transmitted by Aedes aegypti mosquitoes. Currently there are no specific therapeutics and the existing vaccine exhibits limited efficacy. Therefore, vector control remains the best approach to manage disease spread.
We previously demonstrated that DENV-2 infection does not induce innate immunodeficiency (IMD) signalling in the Ae. aegypti Aag2 cell line, recapitulating in vivo data from other groups. Furthermore, prior infection with DENV-2 reduces IMD signalling activation by classical immune stimuli. This project aimed to identify DENV-2 antagonist(s) responsible for this immune inhibition using an RT-qPCR-based screening platform in which IMD signalling is stimulated in cells expressing DENV-2 proteins individually. Our results identified NS4A as a tentative antagonist, which can now be used to enhance our understanding of Ae. aegypti antiviral immunity by investigating virus-host interactions.
The study of vector immunity is hampered by the lack of tools such as antibodies and cell lines. Our group previously created CRISPR-Cas9 knockout Aag2 cell lines, which lack genes essential in the innate immune pathways. These knockout cell lines were created from clonally selected Aag2 cells derived from the heterogeneous parental cell line, and this report also describes the final characterisation of these clones. Results confirm that the cells are embryonic in origin, which confounded our sex analysis. Aag2 clones were confirmed to be persistently infected insect-specific viruses, cell fusing agent virus and Phasi Charoen-like virus. Transfection efficiencies were also determined for the clones of interest. Finally, mutations introduced by CRISPR-Cas9 were characterised in cells derived from one of the clonally selected lines, with one clone identified as the intended mutant, however the IMD pathway-deficient cell clones were determined as wild type.
Ultimately insights into vector antiviral immunity may contribute towards development of transmission-incompetent mosquitoes, thereby reducing the global burden of dengue.
Aedes aegypti is a vector mosquito of major public health importance, transmitting arthropod-borne viruses (arboviruses) such as chikungunya, dengue, yellow fever and Zika viruses. Wild mosquito populations are persistently infected at high prevalence with insect-specific viruses that do not replicate in vertebrate hosts. In experimental settings, acute infections with insect-specific viruses have been shown to modulate arbovirus infection and transmission in Ae. aegypti and other vector mosquitoes. However, the impact of persistent insect-specific virus infections, which arboviruses encounter more commonly in nature, has not been investigated extensively. Cell lines are useful models for studying virus-host interactions, however the available Ae. aegypti cell lines are poorly defined and heterogenous cultures.
We generated single cell-derived clonal cell lines from the commonly used Ae. aegypti cell line Aag2. Two of the fourteen Aag2-derived clonal cell lines generated harboured markedly and consistently reduced levels of the insect-specific bunyavirus Phasi Charoen-like virus (PCLV) known to persistently infect Aag2 cells. In contrast to studies with acute insect-specific virus infections in cell culture and in vivo, we found that pre-existing persistent PCLV infection had no major impact on the replication of the flaviviruses dengue virus and Zika virus, the alphavirus Sindbis virus, or the rhabdovirus vesicular stomatitis virus. We also performed a detailed characterisation of the morphology, transfection efficiency and immune status of our Aag2-derived clonal cell lines, and have made a clone that we term Aag2-AF5 available to the research community as a well-defined cell culture model for arbovirus-vector interaction studies.
Our findings highlight the need for further in vivo studies that more closely recapitulate natural arbovirus transmission settings in which arboviruses encounter mosquitoes harbouring persistent rather than acute insect-specific virus infections. Furthermore, we provide the well-characterised Aag2-derived clonal cell line as a valuable resource to the arbovirus research community.
severe dengue typified by potentially fatal microvascular leakage and hypovolaemic shock.
Blood vessels of the microvasculature are composed of a tubular structure of endothelial cells
ensheathed by perivascular cells (pericytes). Pericytes support endothelial cell barrier
formation and maintenance through paracrine and contact-mediated signalling, and are critical
to microvascular integrity. Pericyte dysfunction has been linked to vascular leakage in
noncommunicable pathologies such as diabetic retinopathy, but has never been linked to
infection-related vascular leakage. Dengue vascular leakage has been shown to result in part
from the direct action of the secreted dengue virus (DENV) non-structural protein NS1 on
endothelial cells. Using primary human vascular cells, we show here that NS1 also causes
pericyte dysfunction, and that NS1-induced endothelial hyperpermeability is more pronounced
in the presence of pericytes. Notably, NS1 specifically disrupted the ability of pericytes to
support endothelial cell function in a 3D microvascular assay, with no effect on pericyte viability
or physiology. These effects are mediated at least in part through contact-independent
paracrine signals involved in endothelial barrier maintenance by pericytes. We therefore
identify a role for pericytes in amplifying NS1-induced microvascular hyperpermeability in
severe dengue, and thus show that pericytes can play a critical role in the aetiology of an
infectious vascular leakage syndrome. These findings open new avenues of research for the
development of drugs and diagnostic assays for combating infection-induced vascular
leakage, such as severe dengue.