Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New findings about protection against pneumococcal disease

31.03.2005


Findings hoped to spur the development of an improved vaccine



Since 2000, U.S. infants have been routinely immunized against pneumococcal (Streptococcus pneumoniae) infection. Now, Boston researchers have made a surprising discovery about natural immunity to pneumococcus. Two related studies, led by Dr. Richard Malley of the Children’s Hospital Boston Division of Infectious Diseases and Dr. Marc Lipsitch of the Harvard School of Public Health, suggest that natural protection from pneumococcal disease may derive from some previously unrecognized immune mechanism, which could possibly be exploited for a new vaccine. The latest study appears in the current (March 29) issue of the Proceedings of the National Academy of Sciences.

In the U.S., before the advent of the pneumococcal conjugate vaccine, known as Prevnar, S. pneumoniae caused more than 7 million ear infections each year, half a million episodes of bacterial pneumonia, and life-threatening cases of meningitis and bacteremia. Prevnar is made up of material from the outer capsule of each of the seven pneumococcal strains most common in the U.S. This material triggers recipients’ immune systems to produce so-called anticapsular antibodies specific to those strains. However, Prevnar doesn’t work against many pneumococcal strains in the developing world, where pneumococcus kills nearly 1 million children annually, and it is expensive and difficult to manufacture, leading to chronic shortages. Moreover, in several studies, use of pneumococcal conjugate vaccines caused non-vaccine strains to become more common, raising concerns that Prevnar could eventually become ineffective even in the U.S. Of 90 known pneumococcal strains, Prevnar only covers seven.


Lipsitch and Malley first conducted epidemiologic studies in unvaccinated toddlers in the U.S., Israel, and Finland. As they reported in January in the online journal PLoS Medicine, the incidence of invasive disease from almost all pneumococcal strains fell by nearly half between 1 and 2 years of age. Yet, anti-capsular antibody concentrations increased only slightly, suggesting that a mechanism other than antibody to the pathogen’s outer capsule may be conferring natural protection against pneumococcal disease.

What then might provide this protection? Looking at the first step of pneumococcal disease, colonization of the nose and throat, Malley and Lipsitch were able to elicit long-lasting immunity to pneumococcus in mice independently of any antibodies. In the current (March 29) Proceedings of the National Academy of Science, they report that when mice were exposed to live pneumococci, or to a whole-cell vaccine developed in Malley’s lab, they were highly immune to pneumococcal colonization -- even if they were genetically unable to make antibodies. Moreover, mice exposed to a single pneumococcal strain became immune not just to that strain, but to others. The immunity appeared to arise from an effect on the immune system’s CD4+ T-cells, since mice that lacked these cells did not develop immunity.

"Textbooks say that naturally-acquired protection against pneumococcal disease depends on the development of antibody against the capsule of the bacterium," says Malley, who is also an assistant professor in pediatrics at Harvard Medical School. "We were surprised to find that protection was independent of not only antibody to the capsule, but also antibody of any specificity."

Overall, their findings suggest that while antibodies are sufficient for protection against pneumococcal disease, they may not represent the natural mechanism of protection.

"An interesting observation is that HIV-infected children, whose CD4+ cells are depleted by the virus, are at about a 200-fold higher risk for pneumococcal disease," Malley adds. "Our experiments in mice may provide an explanation for that vulnerability."

The whole-cell vaccine developed by Malley’s lab could potentially protect against all pneumococcal strains, Malley says. The vaccine, made of killed pneumococcal cells, was shown to prevent colonization and invasive disease when given to animals in the form of nose drops. Malley believes the vaccine stimulates CD4+ T-cells to identify components of pneumococcus that are identical in every strain and to provide protection at the earliest stage of infection, when pneumococcus is colonizing the nasal passages.

The whole-cell vaccine, or a derivative of it, would be a boon for the developing world, because it is inexpensive, covers all pneumococcal strains, and does not require refrigeration. Malley and colleagues are now working to define precisely how the whole-cell vaccine works immunologically, and determine what parts of the killed bacterium provide the actual protection. The ultimate goal is to test the vaccine in adult volunteers, and eventually in children.

Susan Craig | EurekAlert!
Further information:
http://www.childrens.harvard.edu

More articles from Health and Medicine:

nachricht Vanishing capillaries
23.03.2017 | Technische Universität München

nachricht How prenatal maternal infections may affect genetic factors in Autism spectrum disorder
22.03.2017 | University of California - San Diego

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>