Identification, characterization and heparin binding capacity of a spore-wall, virulence protein from the shrimp microsporidian, Enterocytozoon hepatopenaei (EHP)

Abstract

BackgroundThe microsporidian Enterocytozoon hepatopenaei (EHP) is a spore-forming, intracellular parasite that causes an economically debilitating disease (hepatopancreatic microsporidiosis or HPM) in cultured shrimp. HPM is characterized by growth retardation and wide size variation that can result in economic loss for shrimp farmers. Currently, the infection mechanism of EHP in shrimp is poorly understood, especially at the level of host-parasite interaction. In other microsporidia, spore wall proteins have been reported to be involved in host cell recognition. For the host, heparin, a glycosaminoglycan (GAG) molecule found on cell surfaces, has been shown to be recognized by many parasites such as Plasmodium spp. and Leishmania spp.ResultsWe identified and characterized the first spore wall protein of EHP (EhSWP1). EhSWP1 contains three heparin binding motifs (HBMs) at its N-terminus and a Bin-amphiphysin-Rvs-2 (BAR2) domain at its C-terminus. A phylogenetic analysis revealed that EhSWP1 is similar to an uncharacterized spore wall protein from Enterospora canceri. In a cohabitation bioassay using EHP-infected shrimp with naïve shrimp, the expression of EhSWP1 was detected by RT-PCR in the naïve test shrimp at 20 days after the start of cohabitation. Immunofluorescence analysis confirmed that EhSWP1 was localized in the walls of purified, mature spores. Subcellular localization by an immunoelectron assay revealed that EhSWP1 was distributed in both the endospore and exospore layers. An in vitro binding assay, a competition assay and mutagenesis studies revealed that EhSWP1 is a bona fide heparin binding protein.ConclusionsBased on our results, we hypothesize that EhSWP1 is an important host-parasite interaction protein involved in tethering spores to host-cell-surface heparin during the process of infection.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2758-z) contains supplementary material, which is available to authorized users.

Invasion of Host Cells by Microsporidia

“…With the availability of genome data for the Encephalitozoonidae as well as many other microsporidia on MicrosporidiadB.org (part of EuPathdB.org) homologs of these SWPs have been found in most of the Encephalitozoonidae as well as in the other microsporidia genomes found on MicrosporidiadB (such as microsporidia that infect invertebrates) . Examples of such homologs include, Antonospora locustae SWP2 (AlocSWP2) and Enterocytozoon hepatopenaei SWP1 (EHSWP1) (Chen et al, 2017;Jaroenlak et al, 2018).…”

Identification and characterization a novel polar tube protein (NbPTP6) from the microsporidian Nosema bombycis

“…Microsporidians are obligate, intracellular, spore-forming parasites and currently considered as a kind of fungi [ 1 – 4 ]. Since the discovery of the first microsporidian Nosema bombycis from silkworms in the 19th century, there are some microsporidians that infect immunocompromised humans such as Encephalitozoon hellem (Eh), E. cuniculi (Ec) and Enterocytozoon bieneusi (Eb) [ 1 , 5 ]; other microsporidians are insect pathogens such as N. bombycis (Nb), N. ceranae (Nc), and Antonospora locustae (Al) [ 6 – 8 ]. Although microsporidians differ in host range and specificity, they all utilize a similar infection mechanism.…”

Bioinformatics analysis and characterization of a secretory cystatin from Thelohanellus kitauei

“…Total RNA of purified T. kitauei was extracted using Trizol RNA extraction reagent, according to Jaroenlak's method with some modifications (Jaroenlak et al 2018). The extraction used as template RNA in reverse transcription reactions to produce cDNA using an oligo-dT primer, which subsequently used as the template for cloning the TK-cystatin gene.…”