The effect of microfilament inhibitor on the Cryptosporidium infection in vitro

Transcriptome analysis of pig intestinal cell monolayers infected with Cryptosporidium parvum asexual stages

Background

Human cryptosporidiosis is caused primarily by two species of apicomplexan protozoa, Cryptosporidium parvum and C. hominis. In cultured cell monolayers, the parasite undergoes two generations of asexual multiplication (merogony). However, the proportion of parasites completing the life-cycle is low and insufficient to sustain continuous propagation. Due to the intracellular location of meronts and later life-cycle stages, oocyst and sporozoites are the only forms of the parasite that can readily be isolated.

Results

Research on the replicating forms of Cryptosporidium parasites and their interaction with the host cell remains challenging. Based on an RNA-Seq analysis of monolayers of pig epithelial cells infected with C. parvum, here we report on the impact of merogony on the host’s gene regulation. Analysis of the transcriptome of infected and uninfected monolayers demonstrates a significant impact of the infection on host cell gene expression. A total of 813 genes were differentially expressed. Functional terms significantly altered in response to infection include phosphoprotein, RNA binding and acetylation. Upregulation of cell cycle pathways indicates an increase in mitosis. Notably absent from differentially enriched functional categories are stress- and apoptosis-related functions. The comparison of the combined host-parasite transcriptome reveals that C. parvum gene expression is less diverse than the host cell transcriptome and is highly enriched for genes encoding ribosomal functions, such as ribosomal proteins.

Conclusions

These results indicate that C. parvum infection significantly changes host biological functions and provide new insight into gene functions driving early C. parvum intracellular development.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2754-3) contains supplementary material, which is available to authorized users.

Giardia and Cryptosporidium and public health: the epidemiological scenario from the Italian perspective

Giardia and Cryptosporidium spp. are protozoa that cause human and animal disease worldwide and often exhibit zoonotic transmission. This review gives ample information concerning the epidemiology of these parasites in Italy, i.e. prevalence data in humans, farm and pet animals, shellfish and aquatic environment. Moreover, it reports genotyping results obtained from different isolates, with particular emphasis on the spread of host-specific and zoonotic species/genotypes of various origin, and on molecular data that make the Italian situation different from that of other countries. Finally, possible explanations are given for the infrequent reports of Giardia and Cryptosporidium spp. outbreaks, despite widespread faecal contamination by these parasites.

Cryptosporidium parvum regulation of human epithelial cell gene expression

Cryptosporidium parvum is an obligate intracellular protozoan capable of causing life-threatening diarrhoeal disease in immunocompromised individuals. Efforts to develop novel therapeutic strategies have been hampered by the lack of understanding of the pathogenesis of infection. To better understand the host response to C. parvum infection, gene expression profiles of infected human ileocecal adenocarcinoma cells were analysed by using Affymetrix oligonucleotide microarrays containing probe sets for 12,600 human genes. Statistical analysis of expression data from three independent experiments identified 223 genes whose expression was reproducibly regulated by C. parvum infection at 24 h post-inoculation (125 up-regulated and 98 down-regulated), 13 of which were validated by quantitative reverse transcriptase polymerase chain reaction analysis. This analysis revealed the consistent up-regulation of host heat-shock genes and genes for pro-inflammatory chemokines IL-8, RANTES, and SCYB5. Multiple genes for host actin and tubulin genes were up-regulated whereas genes for actin binding proteins were down-regulated, confirming previous observations of host cytoskeleton rearrangement in response to C. parvum infection. In addition, host genes associated with cell proliferation and apoptosis were differentially regulated, reflecting the complexity of host-parasite interaction. Together, this study demonstrated that C. parvum infection results in significant changes in host biochemical pathways and provides new insights into specific biological processes of infectious disease caused by an intracellular protozoan parasite.

In vitro culture of Cryptosporidium muris in a human stomach adenocarcinoma cell line

We investigated the optimal culture conditions for Cryptosporidium muris in a human stomach adenocarcinoma (AGS) cell line by determining the effects of medium pH and of selected supplements on the development of C. muris. The optimum pH of the culture medium required for the development of C. muris was determined to be 6.6. The number of parasites significantly increased during cultivation for 72 hr (p < 0.05) at this level. On the other hand, numbers decreased linearly after 24 hr of incubation at pH 7.5. When cultured in different concentrations of serum, C. muris in media containing 5% FBS induced 4-7 times more parasites than in 1% or 10% serum. Of the six medium supplements examined, only 1 mM pyruvate enhanced the number of C. muris in vitro. Transmission electron microscopic observation showed the developmental stages of C. muris in the cytoplasm of the cells, not in an extracytoplasmic location. The growth of C. muris in AGS cells provides a means of investigating its biological characteristics and of testing its response to therapeutic agents. However, a more optimized culture system is needed for the recovery of oocysts on a large scale in vitro.