Vaccine against Streptococcus pneumonia
Salmonella poisoning typically causes diarrhoea. Now a modified salmonella is being trialled as a vaccine against Streptococcus pneumonia.
Streptococcus pneumonia causes pneumonia, meningitis and bacteraemia and is a leading cause of childhood deaths globally.
The new vaccine use Salmonella bacteria as couriers to deliver key antigens that trigger an immune response against the target pathogen. As Salmonella bacteria are typically responsible for food poisoning they must be inactivated, or 'attenuated', before being used as safe vaccine vectors.
Salmonella is a particularly versatile vector, possessing the ability to deliver antigens from a wide range of pathogens, and therefore could be used against viruses, bacteria and parasites.
This most recent research has found a new, safer way to use Salmonella as a vaccine vector against pneumonia. The new method is based on detoxifying Salmonella lipid A, which is associated with most of the symptoms experienced as a result of adverse reactions to Salmonella vaccines.
The new Salmonella strain was developed to synthesise a surface antigen – pneumococcal PspA – which induces the immune response. When mice were inoculated with this new strain they showed improved immunity to Streptococcus pneumonia and experienced less adverse symptoms thanks to the detoxification of lipid A.