Vaccine candidate against pig infection discovered

Synthesis of oligosaccharides related to Streptococcus suis marks a first step towards a possible vaccination

May 20, 2021

For the first time, researchers at the Max Planck Institute of Colloids and Interfaces have synthesized sugar chains that resemble the envelopes of the four major variations of the bacterium Streptococcus suis. This is a first step for the development of glycoconjugate vaccines against a pathogen that is a serious problem in pigs.

Vaccine candidate forms protective shield against the pathogen Streptococcus suis

Once in the pigsty, the pathogen spreads rapidly, which regularly causes major problems for farms. The bacterium causes diseases such as meningitis, pneumonia and pericarditis, which often lead to death. It also promotes piglet mortality. Treatment is exclusively by antibiotics, as there is no effective commercial vaccine for this pathogen to date. As a zoonotic pathogen, it can also spread to humans.

While glycoconjugate vaccines have been used very successfully in humans against Pneumococcus, Meningococcus and Haemophilus influenzae type b, they remain a largely unexplored option for animals. This may now change: A team of researchers led by Peter H. Seeberger, director of the Max Planck Institute for Colloids and Interfaces, has prepared a collection of 30 novel multiple sugars (oligosaccharides) resembling the polysaccharides related to four major serotypes 2, 3, 9, 14 of the bacterium Streptococcus suis. ‘Using synthetic chemistry, we can recreate relevant sugar structures of pathogens such as Streptococcus suis and use them to produce vaccines candidates. We aim to stimulate the immune system to produce antibodies against these sugars and thereby protect from infections’, says Peter H. Seeberger. Complex sugars such as glycans coat most cells and form the basis for vaccines against bacteria, parasites and viruses.

‘Currently, we are preparing challenge studies in pigs to develop effective vaccines that primarily protect pigs, but also humans working in the swine industry, while reducing the use of antibiotics’, says Shuo Zhang, first author of the study.

How it works

A collection of 30 oligosaccharides was synthesized, the synthetic sugars were printed onto array surfaces to create glycan microarrays. Sera from pigs infected with the bacterium were screened for antibodies against the glycans and helped to discover glycan epitopes that are now the basis for the further vaccine development.

Synthesized oligosaccharides on microarray slides, together with unrelated synthetic glycans for control. Addition of sera from infected pigs, detection of antibodies with fluorescently labeled secondary antibodies.
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