Four novel vaccine candidates developed by a University of Guelph chemist have been recently recognized by the World Health Organization (WHO) for potential use in treating what medical experts call a “hidden pandemic.”

Combatting the growing threat of antimicrobial resistance (AMR) to conventional antibiotics is the goal of researchers including Dr. Mario Monteiro, a professor in the College of Engineering and Physical Sciences, whose vaccine candidates are included in a new WHO report.

The document lists four of his potential vaccines against bacterial infections – three in preclinical development and one in human trials – caused by C. difficile, E. coli, Campylobacter and Shigella. Preclinical trials occur before vaccines are tested in full human clinical trials.

The report, called “Bacterial Vaccines in Clinical and Preclinical Development 2021,” lists 155 vaccine candidates against pathogens on the 2017 WHO bacterial priority pathogens list.

“It’s nice to be recognized, especially by organizations such as this,” said Monteiro. “The main goal is to improve global health.”

Chemist focuses on carbohydrate-based vaccines

Nolan Frame, a student in Dr. Mario Monteiro’s lab, prepares a sample.

His lab in the Department of Chemistry is one of few worldwide that develops carbohydrate-based vaccines, which recognize polysaccharides (sugars) on bacterial surfaces to mount an immune response. Most current vaccine candidates focus on targeting bacterial proteins.

Monteiro’s C. diff vaccine developed in 2017 has been licensed by a U.S. biotech company. It’s one of five C. diff candidates in preclinical development listed by the WHO with high development feasibility.

“C. difficile has been a health problem for a long time that has found no solution,” he said.

The other three U of G vaccines are listed as feasible but facing various challenges for development.

Among them, Monteiro’s E. coli vaccine combines sugars and proteins; it also targets Shigella and Campylobacter. This vaccine is in preclinical development, along with one of two Campylobacter candidate vaccines developed by the U of G chemist.

Both of his Campylobacter vaccine candidates, including one in clinical development, were developed in collaboration with the U.S. Navy.

The WHO report is intended to analyze the complete vaccine pipeline for pathogens on the organization’s priority list, including spelling out lessons learned from vaccines no longer under development.

Antibiotic-resistant strains pose serious health threats

Worldwide, about five million deaths were associated with AMR in 2019. If left untreated, AMR could cause nearly 2.5 million deaths in North America, Europe and Australia between 2015 and 2050, and even more in low- and middle-income countries, according to the report.

Vaccines offer a preventive alternative to treatment with antimicrobial drugs. Besides reducing transmission of drug-resistant strains, vaccines may reduce the use of antibiotics – a key driver of resistance, according to the WHO report.

“That’s what the issue is now,” said Monteiro. “We’re lacking antibiotics to fight against E. coli, C. difficile and Campylobacter. These are serious health issues.”

His lab focuses on pathogens that cause gastrointestinal illnesses.


Dr. Mario Monteiro