New Vaccine for Tuberculosis Holds Promise of Protection

Highlights

• A research team has utilized biobeads that present Mycobacterium antigens on the surface and which were found to induce an immune reaction.
• A non-tuberculosis causing species of Mycobacterium was used for the vaccine which limits risk of the vaccine causing tuberculosis infection.
• This vaccine shows promise of providing immunity and comes nearly 100 years after a previously developed but unsuccessful tuberculosis vaccine.

A newly developed vaccine has shown promise in clinical trials and, if found to be effective, it is the first tuberculosis (TB) vaccine in over a century. The rise in multi-drug resistance tuberculosis has led to an increasing difficulty in treating the disease. TB has resulted in a lot of deaths and has been a huge burden to public health and medical costs.

Biobeads

Biobeads are used by the vaccine onto which antigens are presented from Mycobacterium tuberculosis to the immune system. These biobeads are natural polyesters that are assembled into tiny spheres by bacterium that are not tuberculosis causing.

Cell Mediated Immune Response

The research team had worked on antigen presentation on the biobeads during an earlier study and found that it elicited a cell mediated immune response. The scientists used E.coli to assemble the biobeads. When the scientists studied the antigen presentation in the biobeads, they found that E.coli proteins were also presented on them.

Primary author Dr. Axel Heiser, who is a research scientist at AgResearch Ltd situated at Palmerston North, New Zealand, said that from the findings of the study, the scientists hypothesized that these proteins of E.coli that were presented on the surface of the biobeads, could also function as antigens. The scientists further stated that if these biobeads were synthesized by Mycobacterium species instead of E.coli, then many antigens of Mycobacterium would be represented on the biobeads and this would offer a protective immunity.

However, the main hitch is that E.coli have the necessary enzymes that are required to assemble biobeads stated Dr. Heiser. This encouraged the scientists to clone the bacterium, which allowed the expression of enzymes in M. smegmatis, a Mycobacterium that could not cause tuberculosis. Since this species could not cause the infection, the use of this bacterium in the development of the vaccine will prevent inadvertent infection.

When biobeads were purified and the bacteria killed, the scientists found that they were completely natural and bio-degradable. The Mycobacterial biobeads were then injected into mice and their immune response were studied. The team found that the mice produced an immune response that could potentially prevent TB infection. The scientists would next be introducing TB infection into mice which have been vaccinated to understand the level of protection. They would also be working on better methods of purification of the vaccine and efficient production.

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Benefits of the Biobeads

• The biobeads would be used to provide a new platform where a large combination of antigenic components would be expressed
• It could be compared with live vaccines
• It will have the safety levels of non-infectious material
• There is an absence of genetic material in the biobeads
• The production costs will be cost effective

Tuberculosis

Tuberculosis is a lung infection caused by the bacterium Mycobacterium tuberculosis and Mycobacterium bovis and is one of the top 10 causes of death across the world.

In the year 2015,

• 10.4 million people were infected with TB
• 1.8 million died due to the disease
• 0.4 million people had HIV
• Over 95% of TB related deaths occurs among people in low and middle income families.
• 1 million children became infected with TB
• 170 000 children died due to TB infection

The highest incidence of TB occurs in India and is also high in Indonesia, Pakistan, South Africa, China and Nigeria. Tuberculosis is especially life-threatening among people who are infected with HIV with 35% of HIV deaths associated with TB.

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The major limiting factor about TB infection and disease control is the development of multi-drug resistance, which occurred among an estimated 480 000 people in 2015. The development of this vaccine could soon improve control and spread of the disease.

Mycobacteria usually affect the lungs but they are also found to affect other parts of the body. The infection spreads when an infected individual coughs or sneezes or sometimes even while talking. The infection is most likely to spread to another individual who has a weak immune system.

The symptoms of the lung infection caused due to TB are:

• A very bad cough that lasts for atleast 3 weeks
• Drastic weight loss
• Blood or mucous while coughing
• Loss of appetite
• Sweating at night
• Fever

The previous vaccine for TB was developed in 1921, but it had the risk of causing infection, especially among people who were immune-compromised. The current study that focuses on the development of a TB vaccine would aid in treating people with multi-drug resistance and also in providing immunity for people who are at high risk of developing this disease, like nurses or caregivers.

References:

1. Tuberculosis - (http://www.who.int/mediacentre/factsheets/fs104/en/)
2. Tuberculosis Symptoms - (https://medlineplus.gov/tuberculosis.html)

Source-Medindia