Horton, D. | Search bioRxiv

bioRxiv2018

Survival and development of potato psyllid (Hemiptera: Triozidae) on Convolvulaceae: effects of a plant-fungus symbiosis (Periglandula)

Plant species in the family Solanaceae are the usual hosts of potato psyllid, Bactericera cockerelli ([S]ulc) (Hemiptera: Psylloidea: Triozidae). However, the psyllid has also been shown to develop on some species of Convolvulaceae (bindweeds and morning glories). Developmental success on Convolvulaceae is surprising given the rarity of psyllid species worldwide associated with this plant family. We assayed 14 species of Convolvulaceae across four genera (Convolvulus, Calystegia, Ipomoea, Turbina) to identify species that allow development of potato psyllid. Two populations of psyllids were assayed (Texas, Washington). The Texas population overlaps extensively with native Convolvulaceae, whereas Washington State is noticeably lacking in Convolvulaceae. Results of assays were overlain on a phylogenetic analysis of plant species to examine whether Convolvulaceae distantly related to the typical host (potato) were less likely to allow development than species of Convolvulaceae more closely related. Survival was independent of psyllid population and location of the plant species on our phylogenetic tree. We then examined whether presence of a fungal symbiont of Convolvulaceae (Periglandula spp.) affected psyllid survival. These fungi associate with Convolvulaceae and produce a class of mycotoxins (ergot alkaloids) that may confer protection against plant-feeding arthropods. Periglandula was found in 11 of our 14 species, including in two genera (Convolvulus, Calystegia) not previously known to host the symbiont. Of these 11 species, leaf tissues from five contained large quantities of two classes of ergot alkaloids (clavines, amides of lysergic acid) when evaluated by LC-MS/MS. All five species also harbored Periglandula. No ergot alkaloids were detected in species free of the fungal symbiont. Potato psyllid rapidly died on species found to harbor Periglandula and fungus-produced alkaloids, but survived on species in which the mutualism was absent. These results support the hypothesis that a plant-fungus symbiotic relationship affects the suitability of certain Convolvulaceae to potato psyllid.

ecology↗

bioRxiv2017

Generation of Arctic-like Rabies Viruses Containing Chimeric Glycoproteins Enables Serological Potency Studies.

Rabies viruses have the highest case fatality rate of any known virus and are responsible for an estimated 60,000 deaths each year. This is despite the fact that there are highly efficacious vaccines and postexposure prophylaxis available. However, while it is assumed these biologics provide protection against all rabies virus isolates, there are certain subdivisions of RABV lineages, such as within the Arctic-like RABV (AL rabies virus lineage, where data is limited and thus the potency of existing biologics has not been thoroughly assessed. By fusing the Arctic-like rabies virus envelope glycoprotein ecto- and transmembrane domains with the vesicular stomatitis virus cytoplasmic domain, a high titre (7.7 x 105 - 6.1 x 106 RLU/ml) pseudotyped virus was generated that was subsequently used in a pseudotyped virus neutralisation assay. These results showed that Arctic-like rabies viruses are neutralised to human, canine and feline vaccines and human post-exposure prophylaxis and this was not influenced by the swapping of the cytoplasmic domains (CVS-11 vs CVS-11etmVSVc; r = 0.99, p < 0.0001). This study supports the concept that rabies virus vaccines and newly identified mAbs are able to neutralise rabies virus variants that cluster in a monophyletic clade, referred to as phylogroup I lyssaviruses.

microbiology↗