Featured Research

from universities, journals, and other organizations

Bacterial colonization prior to catching flu may protect against severe illness

Date:
July 10, 2014
Source:
The Wistar Institute
Summary:
Severe illness and even death are likely to result if you develop another respiratory infection after catching the flu. Now, however, a team of researchers has determined that if you reverse the order of infection, pneumococcus bacteria may actually protect against a bad case of the flu. The bacterial protein pneumolysin, a bacterial virulence factor, might protect certain immune system cells (macrophages) in the alveoli of the lungs, preventing inflammation and, thus, pneumonia.

Many studies have shown that more severe illness and even death are likely to result if you develop a secondary respiratory infection after developing influenza. Now, however, a team of researchers based at The Wistar Institute has determined that if you reverse the order of infection, the bacteria Streptococcus pneumoniae (often called pneumococcus) may actually protect against a bad case of the flu.

The researchers discovered that the bacterial protein pneumolysin, which is described as a bacterial virulence factor, might protect macrophages -- a type of immune system cell -- in the lungs. Their findings, performed in a mouse model of influenza infection, appear in the August issue of the journal Virology, available online now.

"Influenza remains a major killer, and there is a preponderance of evidence, both scientific and historical, to show how secondary bacterial infections can be fatal," said Jan Erikson, Ph.D., professor at The Wistar Institute. "However, pneumococci often colonize the respiratory tract asymptomatically, particularly in children, leading us to consider how pre-colonization would impact a subsequent influenza infection."

"Our studies showed that prior colonization offered a protective effect against severe disease in mice," Erikson said, "and we were able to point to the bacterial virulence factor pneumolysin in mediating this protection."

In their investigations, Erikson and her colleagues found that mice who were colonized by Streptococcus pneumonia ten days prior to exposure to influenza were significantly less likely to develop severe disease or pneumonia than mice who were not colonized by the bacteria. In contrast, disease symptoms were exacerbated in mice that were exposed to the flu prior to a secondary pneumococcal infection.

"Mice that were first exposed to pneumococci exhibited less inflammation in the lungs following influenza infection. Virus infection wasn't blocked but the response to it was changed such that the mice no longer showed signs of illness," Erikson said.

The researchers then went about investigating how this might occur. Using mutant strains of pneumococcus that lacked certain proteins, Erikson and her colleagues were able to single out one bacterial protein, pneumolysin, which was necessary to generate the protective effect of pneumococcus. While the exact mechanisms by which pneumolysin lessens the severity of disease remain unknown, Erikson and her colleagues were able to show how alveolar macrophages were less likely to recruit inflammation-causing immune cells to the lungs. Less inflammation would mean less chances of developing pneumonia, which is a major source of flu deaths, Erikson says.

According to Erikson, her results suggest that one factor contributing to the highly variable response to influenza virus infection and severity of disease observed in humans is the presence of specific respiratory tract microbes. "It remains to be seen what lessons we can learn from pneumococcus in lessening flu infections," Erikson said, "but I would be interested in seeing if we could get the benefit of pneumococcal colonization without the associated risks."


Story Source:

The above story is based on materials provided by The Wistar Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. Amaya I. Wolf, Maura C. Strauman, Krystyna Mozdzanowska, Katie L. Williams, Lisa C. Osborne, Hao Shen, Qin Liu, David Garlick, David Artis, Scott E. Hensley, Andrew J. Caton, Jeffrey N. Weiser, Jan Erikson. Pneumolysin expression by streptococcus pneumoniae protects colonized mice from influenza virus-induced disease. Virology, 2014; 462-463: 254 DOI: 10.1016/j.virol.2014.06.019

Cite This Page:

The Wistar Institute. "Bacterial colonization prior to catching flu may protect against severe illness." ScienceDaily. ScienceDaily, 10 July 2014. <www.sciencedaily.com/releases/2014/07/140710131047.htm>.
The Wistar Institute. (2014, July 10). Bacterial colonization prior to catching flu may protect against severe illness. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2014/07/140710131047.htm
The Wistar Institute. "Bacterial colonization prior to catching flu may protect against severe illness." ScienceDaily. www.sciencedaily.com/releases/2014/07/140710131047.htm (accessed September 2, 2014).

Share This




More Health & Medicine News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Get on Your Bike! London Cycling Popularity Soars Despite Danger

Get on Your Bike! London Cycling Popularity Soars Despite Danger

AFP (Sep. 1, 2014) Wedged between buses, lorries and cars, cycling in London isn't for the faint hearted. Nevertheless the number of people choosing to bike in the British capital has doubled over the past 15 years. Duration: 02:27 Video provided by AFP
Powered by NewsLook.com
Can You Train Your Brain To Eat Healthy?

Can You Train Your Brain To Eat Healthy?

Newsy (Sep. 1, 2014) New research says if you condition yourself to eat healthy foods, eventually you'll crave them instead of junk food. Video provided by Newsy
Powered by NewsLook.com
We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Liberia Continues Fight Against Ebola

Liberia Continues Fight Against Ebola

AFP (Aug. 30, 2014) Authorities in Liberia try to stem the spread of the Ebola epidemic by raising awareness and setting up sanitation units for people to wash their hands. Duration: 00:41 Video provided by AFP
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