# Establishment of an in vitro co-infection model of Cryptosporidium parvum and Giardia duodenalis

## TL;DR

This study created a lab model to study how two gut parasites, Cryptosporidium parvum and Giardia duodenalis, interact with intestinal cells and affect cell health.

## Contribution

The novel contribution is the establishment and optimization of an in vitro co-infection model using IPEC-J2 cells for C. parvum and G. duodenalis.

## Key findings

- C. parvum infection did not significantly affect cell viability, but G. duodenalis had a dose-dependent impact.
- Co-infection resulted in higher G. duodenalis gene copy numbers compared to single infections.
- The co-infection model was optimized for 72 hours to study parasite interactions and host cell effects.

## Abstract

The two intestinal protozoan parasites Giardia duodenalis and Cryptosporidium parvum cause infections in a wide spectrum of vertebrates and have also been shown to infect suitable hosts simultaneously. To investigate potential effects between these parasites and on host cells, a co-infection model with IPEC-J2 cells was established.

Optimal infection conditions and several infection doses of both parasites were tested. The effect of Giardia growth medium on IPEC-J2 cells was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay, while the effect of different infection doses of each parasite on host cell viability was investigated by CellTiter Blue cell viability assay. For co-infection, IPEC-J2 cells were first infected with C. parvum sporozoites, and 3.5 h later, G. duodenalis trophozoites were added. Parasite propagation during single infection and co-infection were analyzed by quantitative real-time polymerase chain reaction (qPCR) as well as immunofluorescent staining.

The infection with C. parvum sporozoites had no significant impact on cell viability, while G. duodenalis trophozoites affected cell culture in a dose dependent manner. The amount of gene copies of C. parvum in single and co-infected cells did not differ significantly, while statistically higher amounts of G. duodenalis gene copies in co-infected cell cultures were identified.

In this study, single infections and co-infections of IPEC-J2 cells with C. parvum and G. duodenalis were established and optimized over a period of 72 h.