Salmonella Vaccine

Salmonella, what is it?

Salmonella is a diseased caused by a Gram-negative bacteria. Signs and symptoms of this illness include diarrhea, abdominal cramps, nausea, vomiting, and other things that don’t feel too great. The bacteria works by attaching to the epithelial cells in the small intestine and making these cells engulf them so that it can multiply and hide from phagocyte activity. After it is released by exocytosis, macrophages come to consume it which causes inflammation. It is the disease that explains why your mom tells you to not eat raw cookie dough. Salmonella is famously associated with raw eggs and uncooked chicken.

Although this disease may not be super prevalent in the United States due to food regulations and other factors such as sanitation and education, it has become deadly in places such as Sub-Saharan Africa and parts of Asia with a mortality rate of 20-25% of infected people dying. The specific strain causing such problems is Salmonella Typhi. The increase in illness prevalence is due mainly to immunocompromised people, such as children, the elderly, and HIV patients. A illness that would usually result in a severe upset stomach in healthy individuals, is becoming deadly for the immunocompromised. Due to the massive effect that Salmonella is having in places around the world, scientists in Australia and UC Davis are collaborating to develop an effective vaccine.

Theres a New Vaccine on the Horizon

Traditionally vaccines are targeted towards antibody and T cell responses. The vaccines, either attenuated or inactive, produce an artificially acquired immune response where T cells are activated, antibodies are forms by B cells, and memory cells are stored incase of second exposure. According to Professor Stephen McSorley with Science Daily, there is a type of T cell that has flown under the radar for many years and now scientists are trying to understand its role in the immune system, and its possible role in vaccine therapy. There are two categories of T cells, those that circulate in the body, and those that remain stagnant in tissues. After experimenting with mice and following the path of T-cells with florescent markers, scientists were able to identify specific non-circulating T-cells in the liver that target reoccurring Salmonella Typhi. Thus, efforts are now geared towards manufacturing these memory cells in vaccines and preventing the deadly effects of Salmonella in Africa and Asia.

The research provided in this article does not specifically state what the vaccine will entail and this is probably due to the fact that these efforts are still in an infancy stage. What is known is that the goal is to induce a response from these specific memory t-cells in the liver and my best guest would be with an inactivated virus. Although an attenuated virus would induce better memory and longer immunity, the target population for this vaccine is immunocompromised people, so attenuated virus vaccines are dangerous. But, the immune response generated would be a t-cell response that results in memory cells that get stored in the liver and do not circulate through the body after the infection is gone. Hopefully as research continues, the outcomes will be positive and the therapy cheap enough to get it to the people in these countries that need it.

Science is such an interesting and amazing field because we, as humans, are always discovering new things about the world and how our own bodies work. Not only are we gaining this understanding, but the knowledge is being put to good use saving the lives of those at risk. One day, probably really far in the future, we will know about every type of memory cell and every role they play, and diseases will have to up their game tremendously to keep up as long as we keep vaccinating!