Response of Caenorhabditis elegans during subsequent infections with Gram positive and Gram negative bacteria

Background

The nematode Caenorhabditis elegans is one of the popular model hosts for the study of the evolutionarily conserved mechanism of microbial pathogenesis and innate immunity. C. elegans can be effectively used to study the dynamics of polymicrobial infections. Proteus mirabilis, an opportunistic pathogen, does not cause death in C. elegans. In this study the C. elegans was pre-infected with Staphylococcus aureus to make the C. elegans immunocompromised to study the effect of P. mirabilis in the host.

Methods

This study involved in investigation of impact of subsequent infections at both physiological and molecular levels using C. elegans by killing assays and real time PCR analysis.

Results

The study revealed that 12 h of S. aureus and 80 h of P. mirabilis subsequent infections reduced the life-span of 80% of the infected nematodes. Real time PCR analyses indicated the regulation of innate immune regulatory genes, lysozyme, CUB-like proteins, neuropeptide-like factors, transcription factors of MAP kinase and daf-2–daf-16, insulin-like signaling pathways and C-type lectin family members during polymicrobial infections, indicating possible role and contribution of the above players during host immune response against subsequent infections.

Conclusions

Our findings demonstrate that the vulnerability of a host is an integral part of the S. aureus infection that enables the bacteria to subvert the host immune system, which can lead to the P. mirabilis to exert its pathogenicity in the host C. elegans.