Encephalomyocarditis virus may use different pathways to initiateinfection of primary human cardiomyocytes

Encephalomyocarditis virus (EMCV) caninfect a wide range of vertebrate species including swineand non-human primates, but few data are available forhumans. We therefore wanted to gain further insight intothe mechanisms involved in EMCV infection of humancells. For this purpose, we analyzed the permissiveness ofprimary human cardiomyocytes towards two strains ofEMCV; a pig myocardial strain (B279/95) and a rat strain(1086C). In this study, we show that both strains productivelyinfect primary human cardiomyocytes and inducecomplete cytolysis. Binding and infection inhibitionexperiments indicated that attachment and infection areindependent of sialic acid and heparan sulfate for B279/95and dependent for 1086C. Sequence comparison betweenthe two strains and three-dimensional analysis of the capsidrevealed that six of the seven variable residues are surfaceexposed,suggesting a role for these amino acids in binding.Moreover, analysis of variants isolated from the 1086Cstrain revealed the importance of lysine 231 of VP1 in theattachment of EMCV to cell-surface sialic acid residues.Together, these results show a potential for EMCV strainsto use at least two different binding possibilities to initiateinfection and provide new insights into the mechanismsinvolved in primary human cell recognition by EMCV

Bumble bee parasite strains vary in resistance to phytochemicals

Nectar and pollen contain diverse phytochemicals that can reduce disease in pollinators. However, prior studies showed variable effects of nectar chemicals on infection, which could reflect variable phytochemical resistance among parasite strains. Inter-strain variation in resistance could influence evolutionary interactions between plants, pollinators, and pollinator disease, but testing direct effects of phytochemicals on parasites requires elimination of variation between bees. Using cell cultures of the bumble bee parasite Crithidia bombi, we determined (1) growth-inhibiting effects of nine floral phytochemicals and (2) variation in phytochemical resistance among four parasite strains. C. bombi growth was unaffected by naturally occurring concentrations of the known antitrypanosomal phenolics gallic acid, caffeic acid, and chlorogenic acid. However, C. bombi growth was inhibited by anabasine, eugenol, and thymol. Strains varied >3-fold in phytochemical resistance, suggesting that selection for phytochemical resistance could drive parasite evolution. Inhibitory concentrations of thymol (4.53-22.2 ppm) were similar to concentrations in Thymus vulgaris nectar (mean 5.2 ppm). Exposure of C. bombi to naturally occurring levels of phytochemicals—either within bees or during parasite transmission via flowers—could influence infection in nature. Flowers that produce antiparasitic phytochemical, including thymol, could potentially reduce infection in Bombus populations, thereby counteracting a possible contributor to pollinator decline