Researchers Improve a Way of Injecting Tuberculosis Vaccine

Saturday, January 11, 2020 - 14:07

Based on the World Health Organization (WHO), despite widespread efforts to boost vaccination and treatment of Tuberculosis, each year around 10 million people become ill from the disease, and in 2018 some 1.5 million people died.

According to the Nature report, astonishingly, the only licensed tuberculosis vaccine — BCG (Bacillus Calmette–Guérin), made from a weakened strain of the disease-causing bacterium, Mycobacterium tuberculosis — has been in use for almost a century. Although BCG ably protects infants from systemic infection, it does less well against the lung disease that tuberculosis causes in adolescents and adults.

In the study, researchers in the United States compared the results when BCG was delivered in three different ways to separate groups of macaque monkeys (Macaca mulatta): intravenously; by injection into the skin; or through an aerosol spray.

The team found that intravenous administration yielded more T cells — a type of immune cell — that responded to M. tuberculosis than did either of the other routes. Moreover, these T cells were found throughout the animals’ lungs.

Six months later, some of the macaques were exposed to M. tuberculosis. Of those who received the vaccine intravenously, nine out of ten animals were highly protected against disease and six showed no detectable signs of infection. By contrast, most of the macaques vaccinated by other routes exhibited hallmarks of infection.

The results were a surprise: it was thought that intravenous delivery of the vaccine might limit the severity of disease, but not prevent infection altogether. Instead, intravenous BCG delivery seems to trigger the establishment of a population of T cells in the lungs that can rapidly neutralize M. tuberculosis.

Intravenous vaccines are being developed in other areas, too. One malaria vaccine called PfSPZ is due to be tested in a large clinical trial in 2,100 people this year in Bioko, Equatorial Guinea.

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