[Creation of an avirulent and immunogenic mutant from the rhinopneumonitis virus].

The researchers successfully created a strain of the rhinopneumonitis virus that has lost its harmful properties but still triggers an immune response in horses. This mutated viral strain is being used to develop a vaccine against rhinopneumonitis.

Development of the Mutant Virus

• The research team started the experiment with a virulent strain of the rhinopneumonitis virus, which causes severe clinical symptoms of disease including abortions and respiratory diseases in horses.
• This virulent strain was then cultured or grown in a laboratory using a cellular medium containing 5-iodine-2-desoxiuridine, a type of antimetabolite. Antimetabolites are substances that interfere with the normal metabolic processes within cells, which may lead to genetic changes in those cells. In this case, the antimetabolite resulted in the creation of a mutated strain of the virus.

Characteristics of the Mutant Virus

• Despite these genetic changes, the mutant virus did not lose its ability to trigger an immune response in the host, meaning the viral strain retained its immunogenicity.
• Importantly, the mutant strain completely lost its virulence or ability to cause disease. This crucial characteristic makes it ideal for use in the production of a vaccine.
• These newly acquired biological properties of being avirulent and immunogenic were stable and irreversible, suggesting that the mutant will continue to be harmless and trigger an immune response over time.
• Furthermore, the animals immunized with the mutant strain neither acted as carriers of the virus nor shed the virus, demonstrating that the vaccine will not contribute to the spread of the virus.

Potential Application of the Research

• The mutant virus strain, which is avirulent, immunogenic, stable, and reversible, is being used in the development of a vaccine.
• The research holds promise for protecting horses from rhinopneumonitis without contributing to the spread of the virus, making it a pivotal development in the quest to control and prevent this disease.