Close-Up Of Cropped Hands Inserting Syringe Into Vial of prototype gonorrhea vaccine
Credit: Daniel Chetroni/ EyeEm, Getty Images

An artificial intelligence (AI) model developed by Evaxion Biotech in Denmark has identified two antigens that can be used to develop a messenger (m)RNA vaccine against the sexually transmitted infection gonorrhea caused by the bacteria Neisseria gonorrhoeae.

Gonorrhea can theoretically be treated with antibiotics, but drug resistant strains of the bacteria are becoming increasingly more common and new treatments and/or vaccines are desperately needed.

In this study, a group of researchers based at the University of Massachusetts Medical School carried out a preclinical study in collaboration with Evaxion to assess the efficacy of two antigens identified by Evaxion’s machine learning Efficacy Discriminative Educated Network (EDEN) model at killing off multidrug resistant N. gonorrhoeae in mice.

As reported in the journal mBio, the researchers used the EDEN model to analyze the proteomes of 10 common or medically important strains of N. gonorrhoeae and make a list of 26 vaccine candidates for screening in mice. EDEN predicted how well combinations of different antigens would reduce bacterial load in the animals.

Of all the different possibilities, a combination of NGO1549 (cell divisome protein) and NGO0265 (predicted cell division protein) was found to be most effective at reducing bacterial load, as predicted by EDEN.

The team found that blood taken from mice immunized with the two antigen proteins was able to kill multiple strains of the gonorrhea-causing bacteria in the lab. Immunized mice were then infected with gonorrhea and had a much-reduced bacterial burden.

“That really was a surprise,” said lead investigator Sanjay Ram, a researcher at the University of Massachusetts Chan Medical School, in a press statement. “Nobody would have predicted that these two proteins that were believed not to be surface exposed would work in vaccines, and other researchers reacted with skepticism.”

The publication of this research paper follows on from Evaxion’s announcement last month that it would partner with South African biotech Afrigen Biologics to develop a prophylactic mRNA vaccine against gonorrhea.

The two partners are not the only ones aiming to get a gonorrhea vaccine on the market, something that has proved difficult in the past. GSK also has a vaccine candidate against gonorrhea in Phase II development that achieved FDA fast track status in June. GSK is using nanoparticle technology called “generalized modules for membrane antigens” to develop the vaccine.

Past attempts to develop a gonorrhea vaccine have been complicated by continuing the  evolution of drug-resistant strains and the ability of the bacteria to use different surface markers to disguise itself and evade the immune system. Evaxion and Afrigen are hoping that the use of modern technologies such as AI and mRNA vaccine technology can help to overcome potential obstacles to finally getting a gonorrhea vaccine to the clinic.

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