Featured Research

from universities, journals, and other organizations

Novel pathway for parasite invasion, dissemination discovered

Date:
April 16, 2014
Source:
Rutgers Biomedical and Health Sciences
Summary:
A novel hybrid invasion pathway that starts with the host cell eating the Toxoplasma parasite which, in turn, escapes to form its own vacuolar niche, has been described in a new article by researchers. In humans, toxoplasmosis -- initiated by ingestion of contaminated food and water -- quickly spreads throughout the body. To fight off the infection, the immune system generates a specific type of response called type 1 immunity which kills most of the invading parasites and prevents overgrowth and death of the host.

Parasites known as apicomplexans are responsible for widespread infections, including malaria and toxoplasmosis, in human and animal populations. While most other intracellular pathogens get into our cells first by a process known as phagocytosis or "cellular eating," apicomplexans are well-known exceptions because they infect their host cells by active invasion at the cell's membrane surface. Now, researchers in the Center for Immunity and Inflammation at Rutgers New Jersey Medical School describe a novel hybrid invasion pathway that starts with the host cell eating the Toxoplasma parasite which, in turn, escapes to form its own vacuolar niche.

This study has been published by the journal Proceedings of the National Academy of Sciences.

In humans, toxoplasmosis -- initiated by ingestion of contaminated food and water -- quickly spreads throughout the body. To fight off the infection, the immune system generates a specific type of response called type 1 immunity which kills most of the invading parasites and prevents overgrowth and death of the host. An important cell that senses the parasite and alerts the rest of the immune system is the professional phagocyte -- cells that protect the body from infections -- known as dendritic cells and macrophages. Phagocytes however, are also co-opted by the parasite using these immune cells to ferry infectious stages into the eyes and brain where the parasite remains hidden. In patients whose immune response becomes weakened by AIDS or chemotherapy, reactivation of the parasite infection in the brain can lead to fatal encephalitis.

The team of scientists led by George Yap, an associate professor of medicine at Rutgers, investigated the differences between virulent and avirulent strains of the parasite in how they infected phagocytic cells known as macrophages. Yanlin Zhao, a research associate in the Yap lab, found that virulent strains infected cells via the classical pathway of invasion at the cell surface. However, avirulent strains were surprisingly gobbled up by macrophages, where they soon ended up in lysosomes, the cellular compartment where phagocytosed material are normally digested and degraded. Instead of dying inside lysosomes, the parasite initiated invasion and established a structure known as a moving junction. Escaping through the moving junction, the parasite establishes its vacuolar niche inside the macrophage where it can acquire nutrients and divide. The researchers suggest that their findings represent a new pathway for parasite invasion, which they named phagosome-to-vacuole-invasion or PTVI.

The PTVI pathway of Toxoplasma infection of phagocytic cells may be important for the ability of avirulent strains to induce a stronger immune response, which enhances their dissemination to tissue sites -- such as the eyes, brain and placenta -- and ultimately their increasing prevalence in nature. Future work will determine what phagocytic receptors are involved in PTVI and what parasite genes were lost during the evolution of virulent strains. Andrew Marple, an MD/PhD student at NJMS as well as collaborator at Oxford University and Dartmouth, also contributed to the published work.


Story Source:

The above story is based on materials provided by Rutgers Biomedical and Health Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. Y. Zhao, A. H. Marple, D. J. P. Ferguson, D. J. Bzik, G. S. Yap. Avirulent strains of Toxoplasma gondii infect macrophages by active invasion from the phagosome. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1316841111

Cite This Page:

Rutgers Biomedical and Health Sciences. "Novel pathway for parasite invasion, dissemination discovered." ScienceDaily. ScienceDaily, 16 April 2014. <www.sciencedaily.com/releases/2014/04/140416133203.htm>.
Rutgers Biomedical and Health Sciences. (2014, April 16). Novel pathway for parasite invasion, dissemination discovered. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2014/04/140416133203.htm
Rutgers Biomedical and Health Sciences. "Novel pathway for parasite invasion, dissemination discovered." ScienceDaily. www.sciencedaily.com/releases/2014/04/140416133203.htm (accessed July 26, 2014).

Share This




More Health & Medicine News

Saturday, July 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Beatings and Addiction: Pakistan Drug 'clinic' Tortures Patients

Beatings and Addiction: Pakistan Drug 'clinic' Tortures Patients

AFP (July 24, 2014) A so-called drugs rehab 'clinic' is closed down in Pakistan after police find scores of ‘patients’ chained up alleging serial abuse. Duration 03:05 Video provided by AFP
Powered by NewsLook.com
Too Few Teens Receiving HPV Vaccination, CDC Says

Too Few Teens Receiving HPV Vaccination, CDC Says

Newsy (July 24, 2014) The Centers for Disease Control and Prevention is blaming doctors for the low number of children being vaccinated for HPV. Video provided by Newsy
Powered by NewsLook.com
New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Newsy (July 24, 2014) Sheik Umar Khan has treated many of the people infected in the Ebola outbreak, and now he's become one of them. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins