Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Irradiation preserves T-cell responses in bacterial vaccine

26.07.2006
Using gamma radiation to inactivate bacteria for the preparation of vaccines, instead of traditional heat or chemical methods of inactivation, appears to create a vaccine that is more effective than so-called "killed" vaccines against disease, and has the added advantage of a longer storage life than "live" vaccines, according to researchers at the University of California, San Diego (UCSD) School of Medicine.

Their findings, published in the July 26 issue of the journal Immunity, could result in more potent vaccines that are relatively inexpensive to produce, easy to store, and that can be transported without refrigeration.

In experiments with mice, the researchers, led by Eyal Raz, M.D., Professor of Medicine at UCSD's School of Medicine and Joshua Fierer, M.D., UCSD Professor of Medicine and Chief, Infectious Diseases Section, VA San Diego Healthcare System, demonstrated that a vaccine made with irradiated Listeria monocytogenes (LM) bacteria provided much better protection against disease than vaccine made from heat-killed bacteria. Listeria is a food-borne pathogen that can cause severe meningitis and systemic illness in immuno-compromised individuals. It is on a list of agents that could potentially be used in bioterrorist attacks, compiled by the National Institutes of Health.

To test the irradiated LM, mice were vaccinated with either heat-killed or irradiated vaccine, and then given lethal doses of LM bacteria. All of the unvaccinated or heat-killed vaccinated mice died, but 80% of those vaccinated with the irradiated vaccine survived. Protection against infection lasted more than one year after vaccination with irradiated LM.

"Irradiation is a technically simple process that retains structural features of the bacterial pathogen without destroying the natural antigens or the intrinsic adjuvants. Therefore, a strong immune response is induced in the vaccinated host," said Sandip Datta, M.D., assistant professor in UCSD's Department of Medicine and lead author of the study.

The inactivation, or attenuation, of pathogens has been a strategy for vaccine development since Louis Pasteur first attempted vaccinations nearly 150 years ago. Vaccines are designed to stimulate the immune system to protect against micro-organisms such as viruses or bacteria, by introducing a small amount of the virus or bacteria into the body. When this foreign substance invades the body, the immune system activates certain cells to destroy the invader. If the body is re-invaded by the virus or bacteria in the future, the memory cells will be reactivated and respond faster and more powerfully to destroy the virus.

Immunization with attenuated live micro-organisms promotes a strong immune response, but there are safety, storage and transportation issues with these live vaccines. Immunizations using killed bacteria are very safe, but they don't work as well in eliciting a protective immune response.

"Irradiation destroys the DNA, making the bacteria unable to replicate so it cannot establish an infection," said Raz. "But some residual metabolic activity may survive, so the irradiated bacteria can still find its natural target in the host."

The researchers further showed that, unlike heat-killed bacteria, irradiated bacteria retain the ability to activate the immune system through Toll-like receptors. Toll-like receptors detect signature molecules produced by microbes and help hosts recognize they are under attack by bacteria and trigger an inflammatory response against the bacteria. These receptors are the "sentinels" of the body's innate immune system, and they activate the acquired immune system that provides long-term, specific immunity against a pathogen. The ability of Listeria to activate these receptors appears to be intact after gamma-irradiation.

The researchers speculate that heat-killed bacteria may target an entirely different pathway, because the bacterial molecules that engage these surface cell receptors have been destroyed.

Vaccination with a freeze-dried powder formulation of the irradiated bacteria– a product with the potential to be easily and inexpensively stored and transported, then reconstituted just before use – was also shown to protect mice against lethal infection.

These findings could result in the mass production of more affordable, more effective vaccines for resource-poor regions where vaccines are most needed. The technology could also greatly expedite vaccine production and distribution during epidemic outbreaks, bioterrorist attacks or other biothreats, according to the researchers.

"The resulting vaccines using irradiation might be the next-best approach, after those produced using live bacteria. But they would be very safe, simple and inexpensive to produce," said Raz. "This might not be the ideal vaccine, but its practicality is beyond imagination."

The research team is experimenting with several other bacterial strains in addition to LM. They noted that there is a potential that the process may also work to produce a vaccine against Staphylococcus aureus, an important human pathogen that causes drug-resistant staph infections.

Debra Kain | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>