Investigation of genetic and epigenetic mechanisms of iNOS gene expression in infection of natural populations of Apodemus sylvaticus with the parasite Toxoplasma gondii

Eshenshani, A

Abstract

Toxoplasma gondii is a ubiquitous parasite that infects all warm blooded animals. It can cause pathology in both infected humans and infected animals. There have been many studies investigating the factors the affect infection of laboratory animals, with T. gondii, but relatively few that have studied mechanisms of infection in natural populations. Laboratory studies have shown that the host gene iNOS influences sensitivity and resistance to T. gondii infection. This study sets out to investigate the role of genetic and epigenetic mechanisms of iNOS gene expression in the outcome of infection of natural populations of Apodemus sylvaticus with T. gondii.
Collections of Apodemus sylvaticus were made from the Malham Tarn region of the Yorkshire Dales in the UK. These were tested for T.gondii infection using PCR based detection and each collection showed a significant prevalence ranging between 20 -40% of infected animals. This provided useful sample sets for investigating the role of iNOS gene expression in relation to infected or uninfected animals.
The DNA sequences of the iNOS and Arginase genes of A. sylvaticus were not available in the DNA databases. PCR amplification, based on development of primers, from related rodent sequences were used to build up a partial sequence of both genes. Additional use of a partial genome sequence was used to determine the sequences of several exons and introns in the Apodemus iNOS and Arginase genes. This also included a detailed analysis of the iNOS gene promoter and Exon 1.
Gene expression of the iNOS and Arginase genes were measured by quantitative PCR from mRNA derived cDNA. When the iNOS and Arginase gene expression was measured, uninfected Apodemus showed significantly higher ratio of iNOS/Arginase expression compared to infected animals.
Analysis of single nucleotide polymorphisms and epigenetic polymorphisms (methylated and non-methylated cytosines), were carried out on 144 animals within the iNOS gene promoter and exon 1. Interesting differences between infected an uninfected animal were observed that could potentially be linked to expression differences in iNOS gene expression.
The conclusions of this work are that there are both genetic and epigenetic differences in expression of the iNOS gene in wood mice and that these differences influence infection with Toxoplasma gondii.

Citation

Eshenshani, A. Investigation of genetic and epigenetic mechanisms of iNOS gene expression in infection of natural populations of Apodemus sylvaticus with the parasite Toxoplasma gondii. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: May 7, 2020
• Publicly Available Date: May 7, 2020
• Award Date: Jan 1, 2020