Question

Describe the correlation of the following cell structures or cellular processes with the establishment of microbial infections. Some of these may aid in the infection process, some of the host structures could be used by microbes to establish disease, and some of these could be used by the microbe to resist the immune system or antimicrobial chemotherapy.

Microbial cell: bacterial cell wall

Host cell: nucleus

Answer 1

Bacterial Cell Wall

Bacterial cell wall components helps in adhesion to host cells. Many of these components acts as adhesin and receptors which aid bacterial cell to adhere on host cell. Adhesive ligand on bacteria interact with the receptor on host cell surface and thus form adhesive ligand - receptor complex. Many bacteria form biofilm on such surfaces. Biofilms are communities of bacteria in which many bacteria attach to each other and embedded in slimy extracellular matrix.

Bacterial cell wall is composed of peptidoglycan layer. Both Gram positive and Gram negative bacteria have peptidoglycan layer (thinner in later) strong enough protect them against extreme environmental conditions. Thus, helps in surviving and eastablishing infection. In Gram-negative microbes such as E. coli, Lipopolysachharides (bacterial cell wall derived constituents) is one of the principal component responsible for the induction of septic shock in infections.

Correlation of Bacterial cell wall with host cell Nucleus in Infection and Disease

Eukaryotic cell nucleus is a central organelle for regulation of whole cellular processes and physiology. Pathogenic bacteria release various factors in host cell and thus directly interfering with transcription, chromatin remodelling, RNA splicing or DNA replication and repair. Bacteria employ various strategies to affect the host cell cycle and gene expression programme for their own benefit.

For example, Virulent strains of bacteria cause disease by transferring a segment of their own DNA called T-DNA into the nucleus of host cells. The expression of this T-DNA-encoded genes by the host transcription machinery promote promote production of many amino acids and other components for their own use.