Featured Research

from universities, journals, and other organizations

Two-pronged immune response offers hope for effective Salmonella vaccine

Date:
January 26, 2010
Source:
Wellcome Trust
Summary:
New research renewed hope that an effective vaccine could be developed against non-typhoidal strains of Salmonella. The work suggests that the body's immune system could be primed to tackle even the most resilient of strains.

Research from Malawi, Birmingham and Liverpool has renewed hope that an effective vaccine could be developed against nontyphoidal strains of Salmonella. The work, funded by the Wellcome Trust and GlaxoSmithKline, suggests that the body's immune system could be primed to tackle even the most resilient of strains.

Related Articles


In developed countries, nontyphoidal Salmonella (NTS) strains are mainly food-borne and usually cause gastroenteritis. In rare cases, they can lead to bacteraemia (bacterial infections of the blood). However, in the developing world, bacteraemia is far more common and serious: fatality rates can be as high as almost one in four among children under two years old and HIV-infected adults.

In previous research led by Dr Calman MacLennan, scientists based at the Malawi-Liverpool-Wellcome Trust Clinical Research Programme (MLW) in Blantyre, Malawi , showed that disease-causing strains of NTS were able to survive outside cells in the blood of children. This survival mechanism enables the bacteria to replicate unchecked, possibly leading to high levels of mortality associated with bacteraemia.

Dr MacLennan and colleagues also identified protective Salmonella-specific antibodies that develop in African children within the first two years of life, the period in which the majority of NTS-related cases of bacteraemia occur. These particular antibodies recognise the bacteria in the blood and then kill the bacteria without the help of immune cells. It is possible that these antibodies develop in response to a relatively mild infection by NTS or similar bacteria. Young children who have yet to encounter these bacteria lack the antibodies and are at greatest risk from infection.

However, the Salmonella bacteria can evade the antibodies by hiding away within phagocytes, another group of cells involved in the body's immune reaction. Phagocytes ordinarily 'eat' invasive bacteria before destroying them, but the Salmonella bacteria have adapted to avoid being destroyed once inside the phagocytes.

In addition, some strains have become resistant to the killing effect of antibodies even when they are outside these cells. If the bacteria are not completely cleared from the body, then it is possible for infection to reoccur if a patient's immune system is compromised, for example through HIV infection.

"Nontyphoidal Salmonella is a very serious problem in Africa and we urgently need a vaccine," says Dr MacLennan. "Our previous work gave some hope that a vaccine could be developed that produces antibodies to protect against fatal Salmonella infections. But unless we can develop a vaccine that completely clears the body of bacteria, including resistant strains, such a vaccine could quickly become redundant."

The researchers from the University of Malawi College of Medicine, Liverpool School of Tropical Medicine and the University of Birmingham, published their study in the Proceedings of the National Academy of Sciences, which demonstrates a second way that the immune system uses antibodies to kill the bacteria. The results are encouraging for the prospects of developing a vaccine, suggesting that a vaccine against NTS could be more effective than previously thought.

The research, carried out by Miss Esther Gondwe, a Malawian PhD student at MLW in Dr MacLennan's group, found that the bacteria could be tagged by the antibodies before being 'eaten' by the phagocytes. This made it more likely that the phagocytes would consume them, but would also flag them as unwanted guests, enabling the phagocytes to recognise and destroy them.

This two-pronged approach enables the immune system to kill Salmonella bacteria both within and outside of the blood cells, enabling the body to rid itself of the bacteria including strains that are resistant to killing outside of cells. It further highlights the role that antibodies play in protecting people from Salmonella infection.

"Antibodies clearly play a very important role in protecting people from Salmonella infection," says Dr MacLennan. "This makes even stronger the case for developing a vaccine which can stimulate antibody production. Such a vaccine could potentially save the lives of thousands of African children who would otherwise die."

Dr MacLennan and colleagues will now look for the most effective antibodies for attacking the bacteria in the blood and for activating phagocytes to kill. Finding the best antibodies will be key to developing a much-needed vaccine.


Story Source:

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


Cite This Page:

Wellcome Trust. "Two-pronged immune response offers hope for effective Salmonella vaccine." ScienceDaily. ScienceDaily, 26 January 2010. <www.sciencedaily.com/releases/2010/01/100125173236.htm>.
Wellcome Trust. (2010, January 26). Two-pronged immune response offers hope for effective Salmonella vaccine. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/2010/01/100125173236.htm
Wellcome Trust. "Two-pronged immune response offers hope for effective Salmonella vaccine." ScienceDaily. www.sciencedaily.com/releases/2010/01/100125173236.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Cambodian Capital's Only Working Elephant to Retire in Jungle

Cambodian Capital's Only Working Elephant to Retire in Jungle

AFP (Nov. 25, 2014) Phnom Penh's only working elephant was blessed by a crowd of chanting Buddhist monks Tuesday as she prepared for a life of comfortable jungle retirement after three decades of giving rides to tourists. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Buzz60 (Nov. 24, 2014) A Swedish Adventure racing team travels to try and win a world title, but comes home with something way better: a stray dog that joined the team for much of the grueling 430-mile race. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Yellow-Spotted Turtles Rescued from Trafficking

Yellow-Spotted Turtles Rescued from Trafficking

Reuters - Light News Video Online (Nov. 24, 2014) Hundreds of Amazon River turtles released into the wild in Peru. Sharon Reich reports. Video provided by Reuters
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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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