Attenuation

Attenuation is a reduction in the pathogenic ability (virulence) of bacteria and viruses using various methods.

There are several methods of attenuation:

1. Chemical exposure - treatment with chemicals, such as formaldehyde.

2. Heating is the cultivation of microorganisms at elevated temperatures.

3. Drying - freeze drying of bacteria and viruses.

4. Growing in unfavorable conditions - for example, with a lack of nutrients.

5. Carrying through another organism - successive passages through chicken embryos.

Microorganisms weakened in this way retain the ability to cause an immune response, but lose their pathogenic properties. They are often used for immunization - the introduction of a weakened pathogen in order to create immunity to the disease.

Deterioration is the process of reducing the functionality of something, in this case bacteria and viruses. That is, they lose the ability to parasitize and cause harm. Briefly, I have labeled this “reduction of pathogenicity.”

There are many ways that bacteria can deteriorate, but I will discuss only a few of them, and the most interesting ones.

Cooling Bacteria must feel good before they multiply and multiply only in an environment suitable for them. Therefore, cooling negatively affects them - they feel worse and stop reproducing. It is also known that cold-loving bacteria have the ability to degenerate after the temperature of their environment drops, that is, they can change their DNA after hypothermia. This is called thermolability, and is designated as T°; in the case of bacteria, this indicator is low and ranges from 15 to 30°.

Atlanta (isolation) – reduction of the pathogenic properties of microorganisms under the influence of various chemicals, disinfection, drying, irradiation, temperature changes, exchange of nutrients between the microorganism and the macroorganism. It is caused by mutational variability of part of the microbial population, as well as the selection of typical variants by eliminating low-virulent strains. Occurs as a result of “genetic drift” on the one hand and stabilizing selection on the other. Titer of weakened microbial cultures under different conditions of infectivity or immunogenicity, i.e. reactions on the part of the macroorganism are not the same. In the same type of pathogen, with different passages through animals susceptible to it, it can give both a delayed and normal reaction. Atlanta has significant diagnostic value - not only some natural strains have reduced virulence under certain conditions of its induction, but also those that usually do not have it. The latter were isolated from this source and certain influences were applied to them. Subsequently, their artificial reduction in virulence was called attenuation. Many pathogenic microorganisms, especially viruses and protozoa, have a high ability to survive and reproduce not only in the host, but also in culture under a layer of glass or other protective agent for many days, even weeks. This limits the ability to study virulence factors by monoinfection in cell cultures infected with microorganisms in the culture medium, since the time until cell death—the first or one of the first manifestations of virulence activity—may not be sufficient to produce results. Therefore, cultures can survive their removal after cytotoxicity testing. There may also be a true decline in their ability to infect hosts, including resistance to antimicrobial drugs.

Many years later, similar processes became known as “atenuation” or “induction of attenuation.” This process had the same meaning for medicine as attenuation and was studied using the example of many forms of pathogenic microflora. It was observed before the advent of selective breeding of strains, which consisted of separating (selection, separation) antigenic (capable of causing a reaction in a given host) from non-antigenic. It was found that antigenicity is an independent characteristic of a microorganism. The greatest attention at one time was paid to the weakening of vibrio cholera, diphtheria, dysentery and salmonellosis. Numerous reports of the clinical use of the culture of cholera vibrio Ganata serova 0313 led to the creation of the Serum Institute in the USA (now the Central Institute of Serums and Vaccines). However, it should be noted that attenuation is also used mainly when selecting a strain for a simple animal (mouse, sea urchin). It had a significant (at that time) and disproportionately large role in practical serology due to the development and improvement of an antigenic method for diagnosing infectious diseases of animals and humans based on the reaction