Melbourne - The search for globally effective vaccine against group A streptococci (Strep A, Streptococcus pyogenes) continues. Researchers from the University of Queensland and the Doherty Institute were able to identify common gene signature in almost all global Strep A strains. To do this, they sequenced more than 2,000 samples of bacterial genomes from 22 countries and published their data in Nature Genetics (2019; doi:).
The variety of Strep A strains makes the search for an effective vaccine difficult. So far, most of the studies have come from high-income regions such as the UK and the USA. The latest study results show that current vaccine candidates would have limited effectiveness in low-income areas of the world. The bacterium causes far more problems here.
"For 10 years we have been collecting isolates from all over the world - from Africa, the Pacific, New Zealand and the Australian Aborigines - in order to determine the peculiarities of the pathogen, how it causes disease and why it differs from high-income regions in endemic regions, ”explains Mark Davies, Doherty-Sanger Fellow am.
Pharyngitis caused by Strep A is global phenomenon the most common bacterial diseases in childhood. On the other hand, streptococcal pyoderma occurs mainly in small children in tropical and subtropical climates. The prevalence is very much dependent on personal hygiene and associated with socio-economic status.
Genomic sequencing confirmed the existence of more than 290 genetically different lineages of the Strep A bacterium. Using this data, the researchers were able to identify common gene signature in almost all Strep A strains, which "would be huge step forward in identifying globally effective vaccine candidate," said Davies.
Strep A bacteria are spread worldwide. They cause acute infections of the upper respiratory tract, skin, soft tissues and sepsis. The number of acute streptococcal pharyngitis in Germany is estimated at 1 to 1.5 million per year. If left untreated, the infection can lead to rheumatic heart disease. In some endemic regions, large part of the population is constantly exposed to Strep A. Aborigines in Australia have one of the highest incidence rates of rheumatic heart disease.
“Vaccine developers and the broader scientific community can now use the database we have created to manage the identify common genes that could help develop an effective Group A strep vaccine, ”said Senior Author Mark Walker of the University of Queensland.