Biology subjects

Barribeau, S. M.

Publications and source records attributed to Barribeau, S. M..

4 recordsLinked to original sources

bioRxiv2021

Immune priming can prevent WNV establishment in Culex quinquefasciatus mosquitoes: evidence for immune priming based reversal of WNV-mediated immune suppression.

Mosquito-borne infectious diseases cause wide-spread loss of life and livelihood often in low-income settings. However, control of mosquito-vectored viral diseases such as West Nile virus (WNV) and Japanese encephalitis virus (JEV) remains challenging. Here we use an existing feature of the insect immune system to effectively vaccinate Culex quinquefasciatus mosquitoes against WNV infection. We find that priming mosquitoes by exposure to inactivated WNV reduces their likelihood of developing transmissible infections of WNV after live infection. We used RNA sequencing to identify gene expression in response to WNV and JEV infection, and the role of prior priming exposure on constitutive and induced expression on infection. Infection with either Flavivirus causes broad suppression of gene expression. WNV and JEV infection resulted in suppression of different suites of genes with notable immune genes, such as antimicrobial peptides, being strongly suppressed on WNV infection. We hypothesise that the increased resistance to WNV infection seen in primed mosquitoes may be the result of priming nullifying the immune suppression found in non-primed WNV-fed mosquitoes, potentially through greater expression of mRNA regulatory genes such as cap-binding proteins in primed mosquitoes. Author summaryMosquitoes vector many devastating infectious diseases. Two such vectored viral diseases are West Nile virus (WNV) and Japanese encephalitis virus (JEV). Control of these diseases remains challenging, and no vaccine exists for WNV. Here, we tested whether we could instead vaccinate the mosquitoes against WNV. By injecting mosquitoes with dead WNV we found that we could reduce the number of infected mosquitoes by half. We then used whole-genome RNA sequencing to identify which genes are transcribed, which will help us understand genes that are important for this form of insect immune priming, and for responses to normal WNV and JEV infection. We found that WNV suppresses the expression of many immune genes but these genes are expressed normally in vaccinated mosquitoes. Our findings expand our understanding of mosquito infection with these viruses but also demonstrate how prior exposure to a disease can produce lasting protection.

genomics↗

bioRxiv2021

Life-histories as determinants of infection prevalence for trypanosomatids: A meta-analysis

Trypanosomatids are a diverse family of protozoan parasites, some of which cause devastating human and livestock diseases. There are two distinct infection life-cycles in trypanosomatids; some species complete their entire life-cycle in a single host (monoxenous) while others infect two hosts (dixenous). Dixenous trypanosomatids are mostly vectored by insects, and the human trypanosomatid diseases are caused mainly by vectored parasites. While infection prevalence has been described for subsets of hosts and trypanosomatids, little is known about whether monoxenous and dixenous trypanosomatids differ in infection prevalence. Here, we use meta-analyses to synthesise all published evidence of trypanosomatid infection prevalence for the last two decades, encompassing 931 unique host-trypansomatid systems. In examining 581 studies that describe infection prevalence, we find, strikingly, that monoxenous species are two-fold more prevalent than dixenous species across all hosts. We also find that dixenous trypanosomatids have significantly lower infection prevalence in insects than their non-insect hosts. Within monoxenous trypanosomatids, genera infecting bees are most prevalent and infection prevalence does not vary between wild and managed bees. To our knowledge, these results reveal for the first time, a fundamental difference in infection prevalence according to host specificity where vectored species suffer from lower infection prevalence as a result of a jack of all trades, master of none style trade-off between the vector and subsequent hosts.

evolutionary biology↗

bioRxiv2020

Repurposing the orphan drug nitisinone to control the transmission of African trypanosomiasis

Tsetse transmit African trypanosomiasis, which is a disease fatal to both humans and animals. A vaccine to protect against this disease does not exist so transmission control relies on eliminating tsetse populations. Although neurotoxic insecticides are the gold standard for insect control, they negatively impact the environment and reduce insect pollinator species. Here we present a promising, environment-friendly alternative that targets insect tyrosine metabolism pathway. A bloodmeal contains high levels of tyrosine, which is toxic to haematophagous insects if it is not degraded. RNAi silencing of either the first two enzymes in the tyrosine degradation pathway (TAT and HPPD) was lethal to tsetse. Furthermore, nitisinone (NTBC), an FDA-approved tyrosine catabolism inhibitor, killed tsetse regardless if the drug was orally or topically applied. However, it did not affect bumblebee survival. A mathematical model shows that NTBC could reduce the transmission of African trypanosomiasis in sub-Saharan Africa, thus accelerating current elimination programmes.

biochemistry↗

bioRxiv2020

Genus-wide characterization of bumblebee genomes reveals variation associated with key ecological and behavioral traits of pollinators

Bumblebees are a diverse group of globally important pollinators in natural ecosystems and for agricultural food production. With both eusocial and solitary lifecycle phases, and some social parasite species, they are especially interesting models to understand social evolution, behavior, and ecology. Reports of many species in decline point to pathogen transmission, habitat loss, pesticide usage, and global climate change, as interconnected causes. These threats to bumblebee diversity make our reliance on a handful of well-studied species for agricultural pollination particularly precarious. To broadly sample bumblebee genomic and phenotypic diversity, we de novo sequenced and assembled the genomes of 17 species, representing all 15 subgenera, producing the first genus-wide quantification of genetic and genomic variation potentially underlying key ecological and behavioral traits. The species phylogeny resolves subgenera relationships while incomplete lineage sorting likely drives high levels of gene tree discordance. Five chromosome-level assemblies show a stable 18-chromosome karyotype, with major rearrangements creating 25 chromosomes in social parasites. Differential transposable element activity drives changes in genome sizes, with putative domestications of repetitive sequences influencing gene coding and regulatory potential. Dynamically evolving gene families and signatures of positive selection point to genus-wide variation in processes linked to foraging, diet and metabolism, immunity and detoxification, as well as adaptations for life at high altitudes. These high-quality genomic resources capture natural genetic and phenotypic variation across bumblebees, offering new opportunities to advance our understanding of their remarkable ecological success and to identify and manage current and future threats.

genomics↗