Biology subjects

Popov, V. L.

Publications and source records attributed to Popov, V. L..

4 recordsLinked to original sources

bioRxiv2023

Dehydration induced AePer50 regulates midgut infection in Aedes aegypti

In the face of climate change, mosquitoes will experience evolving climates including longer periods of drought. An important physiological response to dry environments is the protection against water loss or dehydration, here defined as desiccation tolerance. Various environmental factors including temperature are known to alter interactions between the mosquito, Aedes aegypti, and the arboviruses it transmits, but little is known about how low humidity impacts arboviral infection. Here, we report that a gene upregulated in response to desiccation is important for controlling midgut infection. We have identified two genetically diverse lines of Ae. aegypti with marked differences in desiccation tolerance. To understand if the genetic basis underlying desiccation tolerance is the same between the contrasting lines, we compared gene expression profiles between desiccant treated and non-desiccant treated individuals in both the desiccation tolerant and susceptible lines by RNAseq. Gene expression analysis demonstrates that different genes are differentially expressed in response to desiccation stress between desiccation tolerant and susceptible lines. The most highly expressed transcript under desiccation stress in the desiccation susceptible line encodes a peritrophin protein, AePer50. Peritrophins play a crucial role in peritrophic matrix formation after a bloodmeal. Gene silencing of AePer50 by RNAi demonstrates that expression of AePer50 is required for survival of the desiccation susceptible line under desiccation stress, but not for the desiccation tolerant line. Moreover, the knockdown of AePer50 results in higher infection rates and viral replication rates of ZIKV and higher infection rates of CHIKV. Finally, following a bloodmeal, the desiccation susceptible line develops a thicker peritrophic matrix than the desiccation tolerant line. Together these results provide a functional link between the protection against desiccation and midgut infection which has important implications in predicting how climate change will impact mosquito-borne viruses.

microbiology↗

bioRxiv2022

Y-box binding protein 1 interacts with dengue virus nucleocapsid and mediates viral assembly

Infection with dengue virus (DENV) induces vast rearrangements of the endoplasmic reticulum, which allows the compartmentalization of viral RNA replication and particle assembly. Both processes occur in concert with viral and cellular proteins. Prior studies from our group suggest that the host RNA-binding protein (RBP) Y-box binding protein 1 (YBX1) is required for a late step in the DENV replication cycle. Here we report that YBX1 interacts with the viral nucleocapsid, distributes to DENV assembly sites and is required for efficient assembly of intracellular infectious virions and their secretion. Genetic ablation of YBX1 decreased the spatial proximity between capsid and envelope, increased the susceptibility of envelope to proteinase-K mediated degradation, resulted in the formation of rough empty-looking particles, and decreased the secretion of viral particles. We propose a model wherein YBX1 enables the interaction between the viral nucleocapsid with the structural protein E, which is required for proper assembly of intracellular virus particles and their secretion. ImportanceThe global incidence of dengue virus (DENV) infections has steadily increased over the past decades representing an enormous challenge for public health. During infection, DENV viral RNA interacts with numerous host RNA binding proteins (RBPs) that aid viral replication and thus constitute potential molecular targets to curb infection. We recently reported that Y-box-binding protein 1 (YBX1) interacts with DENV RNA and is required at a late step of the replication cycle. Here we describe the molecular mechanism by which YBX1 mediates DENV infection. We show that YBX1 interacts with the viral nucleocapsid, distributes to DENV assembly sites and is required for efficient assembly of intracellular infectious virions. These results provide important insights into DENV assembly, revealing novel functions of host RBPs during viral infection and opening new avenues for antiviral intervention.

molecular biology↗

bioRxiv2020

Microbial interactions in the mosquito gut determine Serratia colonization and blood feeding propensity.

How microbe-microbe interactions dictate microbial complexity in the mosquito gut is unclear. Previously we found that Serratia, a gut symbiont that alters vector competence and is being considered for vector control, poorly colonized Aedes aegypti yet was abundant in Culex quinquefasciatus reared under identical conditions. To investigate the incompatibility between Serratia and Ae. aegypti, we characterized two distinct strains of Serratia marcescens from Cx. quinquefasciatus and examined their ability to infect Ae. aegypti. Both Serratia strains poorly infected Ae. aegypti, but when microbiome homeostasis was disrupted, the prevalence and titers of Serratia were similar to the infection in its native host. Examination of multiple genetically diverse Ae. aegypti lines found microbial interference to S. marcescens was commonplace, however one line of Ae. aegypti was susceptible to infection. Microbiome analysis of resistant and susceptible lines indicated an inverse correlation between Enterobacteriaceae bacteria and Serratia, and experimental co-infections in a gnotobiotic system recapitulated the interference phenotype. Furthermore, we observed an effect on host behaviour; Serratia exposure to Ae. aegypti disrupted their feeding behaviour, and this phenotype was also reliant on interactions with their native microbiota. Our work highlights the complexity of host-microbe interactions and provides evidence that microbial interactions influence mosquito behaviour.

microbiology↗

bioRxiv2019

Gut-associated bacteria invade the midgut epithelium of Aedes aegypti and stimulate innate immunity and suppress Zika virus infection in cells.

Microbiota within mosquitoes influence nutrition, immunity, fecundity, and the capacity to transmit pathogens. Despite their importance, we have a limited understanding of host-microbiota interactions, especially at the cellular level. It is evident bacterial symbionts that are localized within the midgut also infect other organs within the mosquito; however, the route these symbionts take to colonize other tissues is unknown. Here, utilizing the gentamicin protection assay, we showed that the bacterial symbionts Cedecea and Serratia have the capacity to invade and reside intracellularly within mosquito cells. Symbiotic bacteria were found within a vacuole and bacterial replication was observed in mosquito cell by transmission electron microscopy, indicating bacteria were adapted to the intracellular milieu. Using gene silencing, we determined that bacteria exploited host factors, including actin and integrin receptors, to actively invade mosquito cells. As microbiota can affect pathogens within mosquitoes, we examined the influence of intracellular symbionts on Zika virus (ZIKV) infection. Mosquito cells harbouring intracellular bacteria had significantly less ZIKV compared to uninfected cells or cells exposed to non-invasive bacteria. Intracellular bacteria were observed to substantially upregulate the Toll and IMD innate immune pathways, providing a possible mechanism mediating these anti-viral effects. Examining mono-axenically infected mosquitoes using transmission electron and fluorescent microscopy revealed that bacteria occupied an intracellular niche in vivo. Our results provided evidence that bacteria that associate with the midgut of mosquitoes have intracellular lifestyles which likely have implications for mosquito biology and pathogen infection. This study expands our understanding of host-microbiota interactions in mosquitoes, which is important as symbiont microbes are being exploited for vector control strategies.

microbiology↗