Featured Research

from universities, journals, and other organizations

Essential factor for Lyme disease transmission identified

Date:
December 19, 2013
Source:
Public Library of Science
Summary:
Borrelia burgdorferi, the bacterium that causes Lyme disease, hitchhikes in ticks for dissemination to mammalian hosts -- including humans. A new article identifies HrpA, an RNA helicase, as a crucial player in the transmission from ticks to mammals. Scientists have analyzed the molecular function of the HrpA protein and explored its role in the bacterium's complicated life cycle, in particular for transmission of the pathogen.

Deer ticks (Ixodes scapularis) were infected with B. burgdorferi.
Credit: Image Credit: Melissa J. Caimano, University of Connecticut Health Center.

Borrelia burgdorferi, the bacterium that causes Lyme disease, hitchhikes in ticks for dissemination to mammalian hosts--including humans. An article in the 19 December issue of PLOS Pathogens identifies HrpA, an RNA helicase, as a crucial player in the transmission from ticks to mammals.

George Chaconas, from the University of Calgary, Canada, and a member of the university's Snyder Institute for Chronic Diseases, and colleagues had previously identified HrpA as a modulator of B. burgdorferi protein expression. For this study, Chaconas' group joined forces with Justin Radolf and Melissa Caimano from the University of Connecticut Health Center, USA, to analyze the molecular function of the HrpA protein and further explore its role in the bacterium's complicated life cycle, in particular for transmission of the pathogen.

Its DNA sequence suggests that HrpA is an RNA helicase, a protein that can harvest energy from the cell's stores, use it to unwind RNA, and so regulate translation of RNA into protein. Most bacteria have several putative helicases, including one from the HrpA family, but nothing was known about the actual HrpA function from other species. HrpA is the only putative RNA helicase in B. burgdorferi, and the scientists found that it indeed possesses the multiple activities characteristic of a helicase: it can bind to RNA and use its ATPase activity to harvest energy, which in turn is used to unwind the RNA strand. They also showed that these activities are involved in the regulation of target RNAs.

When the scientists tested whether mutant B. burgdorferi that lacked the hrpA gene could infect mice, they found that the mutant bacteria could not. For this experiment, the scientists injected normal or mutant bacteria directly into mice, and subsequently tested mouse blood, skin, bladder, or joint tissue for the presence of bacteria. Normal bacteria could be recovered from all tissues after a week and up to 4 weeks post injection, but mutant bacteria were undetectable even after one week, suggesting that they were unable to survive or multiply in the mammalian host.

HrpA-deficient bacteria were also unable to infect mice using the natural route, i.e. via a bite from an infected tick. This was not because the mutant bacteria were unable to grow or survive in the ticks. Rather the mutants could not exit the tick midgut or enter the salivary glands, where Borrelia needs to be for successful transmission during feeding; even right after the engorged ticks fell off, mutant bacteria were not detectable in the mouse skin around the attachment site.

The authors say, "We now know that HrpA is involved in both parts of the B. burgdorferi lifecycle: animal infection and tick transmission, making it a very important protein in B. burgdorferi gene regulation and establishing gene regulation through an RNA helicase as an important regulatory pathway in the Lyme spirochete."


Story Source:

The above story is based on materials provided by Public Library of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Aydan Salman-Dilgimen, Pierre-Olivier Hardy, Justin D. Radolf, Melissa J. Caimano, George Chaconas. HrpA, an RNA Helicase Involved in RNA Processing, Is Required for Mouse Infectivity and Tick Transmission of the Lyme Disease Spirochete. PLoS Pathogens, 2013; 9 (12): e1003841 DOI: 10.1371/journal.ppat.1003841

Cite This Page:

Public Library of Science. "Essential factor for Lyme disease transmission identified." ScienceDaily. ScienceDaily, 19 December 2013. <www.sciencedaily.com/releases/2013/12/131219200040.htm>.
Public Library of Science. (2013, December 19). Essential factor for Lyme disease transmission identified. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2013/12/131219200040.htm
Public Library of Science. "Essential factor for Lyme disease transmission identified." ScienceDaily. www.sciencedaily.com/releases/2013/12/131219200040.htm (accessed April 21, 2014).

Share This



More Health & Medicine News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Breakfast Foods Are Getting Pricier

Breakfast Foods Are Getting Pricier

AP (Apr. 21, 2014) Breakfast is now being served with a side of sticker shock. The cost of morning staples like bacon, coffee and orange juice is on the rise because of global supply problems. (April 21) Video provided by AP
Powered by NewsLook.com
Nine-Month-Old Baby Can't Open His Mouth

Nine-Month-Old Baby Can't Open His Mouth

Newsy (Apr. 19, 2014) Nine-month-old Wyatt Scott was born with a rare disorder called congenital trismus, which prevents him from opening his mouth. Video provided by Newsy
Powered by NewsLook.com
'Holy Grail' Of Weight Loss? New Find Could Be It

'Holy Grail' Of Weight Loss? New Find Could Be It

Newsy (Apr. 18, 2014) In a potential breakthrough for future obesity treatments, scientists have used MRI scans to pinpoint brown fat in a living adult for the first time. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. 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