Modified TB bacteria shows protection in mice

A vaccine made up of a genetically modified bacterium that is closely related to the tuberculosis causing Mycobacterium tuberculosis protected mice against TB in a recent study.
While a vaccine to prevent TB infection called bacille Calmette-Guerin is widely available, it only provides limited protection and may cause severe TB infection in infants infected with HIV, which restricts its use in certain countries, UPI reports.
William R. Jacobs, Jr., the study leader from the Albert Einstein College of Medicine in New York, said that TB kills an estimated 1.7 million worldwide every year. Jacobs and his colleagues genetically modified M. smegmatis, a relative of Mycobacterium TB, which is genetically harmless to humans. Jacobs' team replaced a set of the harmless bacteria genes called esx-3, which is a DNA sequence that is unusually consistent across species, with the corresponding but not identical set of genes from Mycobacterium TB.
The researchers vaccinated mice with the modified form of M. smegmatis, essentially delivering the Mycobacterium TB version of esx-3, without including the bacterial components that would lead to infection, according to UPI. They then challenged the mice with Mycobacterium TB.
The study found that mice receiving the experimental vaccine had 1,000 times lower levels of TB bacteria than in those that received bacille Calmette-Guerin. The results of the study suggest that modifying M. smegmatis can induce a strong immune response in mice to protect them from TB.