Bacterial RNA will increase the effectiveness of vaccines

It is known that vaccination with live weakened bacteria is more effective than vaccination with drugs containing killed microorganisms. The immune system recognizes certain components of the bacterial cell and remembers them, acquiring resistance to the corresponding pathogen. However, the introduction of live microorganisms is always associated with the risk of developing the disease against which vaccination is directed. For this reason, doctors usually use vaccines based on killed bacteria – safer, but also less effective.

A group of researchers led by Professor Michael Muller from Wageningen University, the Netherlands, used genomics and modern computer analysis methods to study differences in the immune system's responses to dead and live bacteria. The purpose of this work was to find an answer to a number of questions:

• How does the immune system distinguish living bacteria from dead ones?
• The absence of which component in dead bacteria causes the inferiority of the emerging immunity?
• Is it possible to get full-fledged immunity by adding this component to a vaccine based on killed pathogens?

In order to identify the mysterious component, scientists killed bacteria by various methods: using alcohol, ultraviolet radiation, antibiotics and formaldehyde. They suggested that different methods of killing destroy different components of the bacterial cell. After that, the killed bacteria were used to make vaccines that were administered to healthy volunteers. As the researchers expected, almost all the bacteria killed caused the formation of defective immunity. The only exception was bacteria treated with formaldehyde. The use of formaldehyde was the only method that did not lead to the destruction of bacterial informational RNAs (mRNAs).

To confirm that mRNA is the desired substance, scientists introduced bacterial mRNA into vaccines made from killed bacteria. And indeed, vaccination with the resulting "cocktail" ensured the formation of a full-fledged immunity.

The authors believe that the data they have obtained will not only lead to the emergence of new improved vaccines, but also help in the fight against chronic inflammatory processes caused by facultative microflora of the body, especially bacteria inhabiting the gastrointestinal tract. They claim that knowledge of the exact molecular mechanisms of the formation of immune responses to the presence of bacteria will effectively counteract infection.

Article by Leif E. Sander et al. Detection of prokaryotic mRNA signs microbial viability and promotes immunity is published on May 22 in the preliminary on-line version of the journal Nature.

Evgeniya Ryabtseva
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of Wageningen University: Better vaccines thanks to RNA.

03.06.2011