Cryptosporidium parvum Elongation Factor 1α Participates in the Formation of Base Structure at the Infection Site During Invasion

Abstract

Background Cryptosporidium is a genus of apicomplexan parasites, the causative agents of cryptosporidiosis in humans and/or animals. Although most apicomplexans parasitize within the host cell cytosols, Cryptosporidium resides on top of host cells, but it is embraced by a double-layer parasitophorous vacuole membrane derived from host cell. There is an electron-dense band to separate the parasite from host cell cytoplasm, making it as an intracellular but extracytoplasmic parasite. However, little is known on the molecular machinery at the host cell-parasite interface. Methods Cryptosporidium parvum at various developmental stages were obtained by infecting HCT-8 cells cultured in vitro. Immunofluorescence assay was used to detect CpEF1α with a polyclonal antibody and host cell F-actin with rhodamine-phalloidin. Recombinant CpEF1α protein was used to evaluate its effect on the invasion by the parasite. Results We discovered that a C parvum translation elongation factor 1α (CpEF1α) was discharged from the invading sporozoites into host cells, forming a crescent-shaped patch that fully resembles the electron-dense band. At the same time, host cell F-actin aggregated to form a globular-shaped plug beneath the CpEF1α patch. The CpEF1α patch remained for most of the time but became weakened and dissolved upon the completion of the invasion process. In addition, recombinant CpEF1α protein could effectively interfere the invasion of sporozoites into host cells. Conclusions CpEF1α plays a role in the parasite invasion by participating in the formation of electron-dense band at the base of the parasite infection site.

Cryptosporidiosis Modulates the Gut Microbiome Metabolism and Immune Response in an Infected Host

“…Host actin has shown to be essential for the invasion and replication of apicomplexan parasites such as Cryptosporidium [43]. Our results were in line with previous cell culture and microscopy studies showing that Cryptosporidium forces the host actins to assemble and polymerise into plaque structures in order to complete the invasion process by sporozoites [44,45].…”

Discovery of New Microneme Proteins in Cryptosporidium parvum and Implication of the Roles of a Rhomboid Membrane Protein (CpROM1) in Host–Parasite Interaction

“…Transcript levels were substantially higher in oocysts and sporozoites than in the intracellular stages, for example, transcript levels were 24.3-fold higher in sporozoites than in intracellular parasites 6 h post-infection (hpi) and 4.8-to 7.5-fold higher than the levels at 3, 12, 24, 48, and 72 hpi. The qRT-PCR assay was reliable because the transcriptomic profiles detected in parallel for three reference genes (CpEF1α, CpLDH, and CpTIPH) followed the same patterns as those previously reported (29,38,39). The native protein in C. parvum oocysts was also detected using Western blot analysis (Figure 5B).…”

Cryptosporidiosis Modulates the Gut Microbiome and Metabolism in a Murine Infection Model

“…Host actin has been shown to be essential for the invasion and replication of apicomplexan parasites such as Cryptosporidium [44]. Previous cell culture and microscopy studies have showed that Cryptosporidium forces the host actins to assemble and polymerise into plaque structures in order to complete the invasion process by sporozoites [45,46]. However, upregulation of actin as a result of parasite infection has not been previously reported.…”