# Evaluation of the Expression of Virulence Factors of V. cholerae After Interaction With the Human Colon Adenocarcinoma (Caco-2) Cell Line

## TL;DR

This study shows how V. cholerae changes its gene expression when interacting with human colon cells, revealing differences between two biotypes that could help in managing cholera.

## Contribution

The study compares gene expression changes in two V. cholerae biotypes after interaction with Caco-2 cells, highlighting biotype-specific virulence responses.

## Key findings

- The classical biotype showed a 6-fold increase in ctxAB gene expression compared to the El Tor biotype's 2-fold increase.
- The hlyA gene expression increased 13-fold in the classical biotype and 7-fold in the El Tor biotype after Caco-2 interaction.
- TcpA gene expression increased significantly in the classical biotype but not in the El Tor biotype when interacting with Caco-2 cells.

## Abstract

Cholera remains a global challenge, and understanding how V. cholerae adapts to environmental condition is essential for innovating new management strategies. This research aims to examine the expression of ctxAB, tcpA, and hlyA genes in V. cholerae (El Tor and classical biotypes) after interaction with Caco-2 cells compared to brain heart infusion (BHI) broth. After assaying of viability of Caco-2 cells against V. cholerae at multiplicity of infection (MOI) of 10, 20, 50, and 80, the number of bacteria attached to Caco-2 cells was determined using the adhesion assay. To conduct a valid comparison, an equivalent number of bacteria that attached to Caco-2 cells was inoculated into BHI broth. The expression of ctxAB, tcpA, and hlyA genes in V. cholerae (El Tor and classical biotypes) was assayed using the real-time PCR method. After interaction of Caco-2 cells with V. cholerae, the expression of the genes ctxAB, tcpA, and hlyA in the El Tor biotype increased by 2-, 1.02-, and 7-fold, respectively, while in the classical biotype, it increased by 6-, 2-, and 13-fold, respectively. The expression of the genes ctxAB and hlyA was significantly increased in Caco-2 cells in both biotypes. There was a significant increase in the expression of the gene tcpA in the classical biotype, while no significant increase was detected in the expression of this gene in the El Tor biotype. Caco-2 cells induced the highest increase in hlyA gene expression in the classical biotype, while there was no significant effect on tcpA gene expression in the El Tor biotype of V. cholerae. In conclusion, V. cholerae showed greater pathogenicity in the Caco-2 cells. Knowing the behavior of V. cholerae in different conditions can lead to create innovative strategies for combating and managing cholera.