APR 29, 2020 8:43 PM PDT

Toxoplasma Infections Can Cause Epigenetic Changes in Males

WRITTEN BY: Carmen Leitch

It's been estimated that anywhere from 25 to 80 percent of the world's population is infected with a parasite called Toxoplasma gondii. Most of the time, the illness caused by the parasitic infection is mild, but it can cause more serious problems in people with weak immune systems, infants, and pregnant women. Researchers have now found that the parasite can cause epigenetic changes in male mice that affects gene expression in their offspring. There were alterations in the brain function and behavior of pups born to male mice infected with Toxoplasma gondii (compared to pups born to uninfected male mice).

Gene expression has to be carefully controlled by cells, and there are a variety of ways that genes are regulated. One of those ways is epigenetic tags - chemical groups that modify the genome. Toxoplasma infections caused epigenetic changes in the sperm of male mice. There is evidence that shows that these types of epigenetic changes in sperm are passed down to offspring.

Study co-author and Associate Professor Chris Tonkin noted that people can be infected with the parasite for decades, which has been associated with symptoms of mental illness. "Toxoplasma infections have been shown to cause long-term epigenetic changes in a range of cells around our body. These are changes that do not alter the genetic sequence of DNA, but influence gene expression - that is, which genes are switched on or off," he said. "As other epigenetic changes in fathers - such as those caused by trauma or smoking - can influence their children, we decided to look at whether the effects of epigenetic changes caused by Toxoplasma infection could also be passed between generations."

Toxoplasma parasites within cells can form these visually appealing 'bouquets' (which have been artificially coloured), but they can cause severe illness and long-lasting health impacts. Our latest research suggests Toxoplasma infection may also impact the brain health of subsequent generations. / Credit: Walter and Eliza Hall Institute, Australia

The mouse model used in this study showed that these epigenetic changes were having an impact. "We discovered that Toxoplasma infection alters levels of DNA-like molecules, called small RNA, that are carried by sperm," explained Walter and Eliza Hall Institute researcher Dr. Shiraz Tyebji. "These changes in small RNA levels affect gene expression, and so could potentially influence brain development and behavior of offspring. We were stunned to see that even the next generation - the 'grandchildren' of the original infected male - displayed changes in their behavior."

This work is the first to show that an infection can cause heritable epigenetic changes, but has to be confirmed in people, noted study co-author Professor Anthony Hannan at the Florey Institute of Neuroscience and Mental Health. "While our studies were in mice, it raises an important question about whether infections in human fathers before conception also impact their children," he said.

This image shows neurons and their connections to each other in red and yellow, and the cell's DNA in blue. These neurons were used to study the impact of Toxoplasma infection on cells. / Credit: Walter and Eliza Hall Institute, Australia

"We normally think more about how infectious diseases in women affect the developing fetus, but perhaps certain infections in men could have long-term impacts on subsequent generations' health. This is certainly something we are following up, both looking at what is happening in humans, as well as investigating infections other than Toxoplasma, including animal models of infection with the SARS-CoV-2 virus which causes COVID-19."

Sources: AAAS/Eurekalert! via Walter and Eliza Hall Institute, Cell Reports

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAR 23, 2020
Genetics & Genomics
MAR 23, 2020
Diagnosing Cancer by Looking for Microbial DNA in the Blood
Liquid biopsies aim to diagnose a disease with only a bit of biological fluid, usually blood.
MAR 23, 2020
Cell & Molecular Biology
MAR 23, 2020
How a Father's Diet Can Impact the Health of His Offspring
When fathers consume a diet high in fat or low in protein it can increase the risk of metabolic disorders like diabetes ...
APR 07, 2020
Genetics & Genomics
APR 07, 2020
One Gene Can Accelerate or Slow ALS Progression
Mutations in a single gene had different biological impacts depending on the context.
APR 12, 2020
Genetics & Genomics
APR 12, 2020
Even Brief Exposure to Air Pollution Can Affect Gene Expression
Studies in mice and humans have shown that the negative health effects of pollution are accompanied by changes in gene e ...
APR 20, 2020
Genetics & Genomics
APR 20, 2020
Advances in Gene Therapy for Neurons
New research may aid in the development of gene therapies for diseases like Alzheimer's and Parkinson's.
MAY 06, 2020
Genetics & Genomics
MAY 06, 2020
Advances in Genome Sequencing Technology
We've come a long way from the human genome project, which took years to complete. It now takes about 6 hours to sequenc ...
Loading Comments...