Staphylococcal enterotoxin B (
SEB) is an
enterotoxinAn enterotoxin is a protein toxin released by a microorganism in the intestine. Enterotoxins are chromosomally encoded exotoxins that are produced and secreted from several bacterial organisms. They are often heat-stable, and are of low molecular weight and water-soluble...
produced by the bacterium
Staphylococcus aureusStaphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
. It is a common cause of food poisoning, with severe
diarrheaDiarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
,
nauseaNausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
and intestinal cramping often starting within a few hours of ingestion.. Being quite stable, the toxin may remain active even after the contaminating bacteria are killed. It can withstand boiling at 100°C for a few minutes.
GastroenteritisGastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...
occurs because SEB is a
superantigenSuperantigens are a class of antigens which cause non-specific activation of T-cells resulting in oligoclonal T cell activation and massive cytokine release...
, causing the immune system to release a large amount of
cytokineCytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
s that lead to significant inflammation.
Biological Warfare
The US Army Chemical Warfare Service may have supplied a vial of SEB to
OSSThe Office of Strategic Services was a United States intelligence agency formed during World War II. It was the wartime intelligence agency, and it was a predecessor of the Central Intelligence Agency...
agents during the Second World War to incapacitate a Nazi agent in
North AfricaNorth Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
at the time of the
D-dayD-Day is a term often used in military parlance to denote the day on which a combat attack or operation is to be initiated. "D-Day" often represents a variable, designating the day upon which some significant event will occur or has occurred; see Military designation of days and hours for similar...
invasion to prevent effective handling of intelligence in the early hours of the invasion.
The United States weaponized SEB originally as agent
PG, later
UC, during the
Cold WarThe Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
. It was anticipated to have a rate-of-action of several hours and a duration-of-action of 1 - 2 days. There was a crash program to deliver a usable weapon, and there was a plan to use it in the opening hours of an invasion of Cuba during the
Cuban Missile CrisisThe Cuban Missile Crisis was a confrontation among the Soviet Union, Cuba and the United States in October 1962, during the Cold War...
, but the plan was later rejected.
Field trials with the A/B 45-4 dry agent spray tank demonstrated that a 95 kg payload of UC was capable of neutralizing a 1000 square miles (2,590 km²) target.
The ICt
50 of UC is 2 mg·
minA minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
/m³, with a
probitIn probability theory and statistics, the probit function is the inverse cumulative distribution function , or quantile function associated with the standard normal distribution...
slope of 1. The is 5 mg·
minA minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
/m³, and unlike the per oral route is known to have a neurotoxic effect when inhaled.