Antiserum is blood serum

Blood serum

In blood, the serum is the component that is neither a blood cell nor a clotting factor; it is the blood plasma with the fibrinogens removed...

 containing polyclonal antibodies. Antiserum is used to pass on passive immunity

Immunity (medical)

Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...

 to many diseases. Passive antibody transfusion from a previous human survivor is the only known effective treatment for Ebola

Ebola

Ebola virus disease is the name for the human disease which may be caused by any of the four known ebolaviruses. These four viruses are: Bundibugyo virus , Ebola virus , Sudan virus , and Taï Forest virus...

 infection (but with little success rate).

The most common use of antiserum in humans is as antitoxin

Antitoxin

An antitoxin is an antibody with the ability to neutralize a specific toxin. Antitoxins are produced by certain animals, plants, and bacteria. Although they are most effective in neutralizing toxins, they can kill bacteria and other microorganisms. Antitoxins are made within organisms, but can be...

 or antivenom, to treat envenomation

Envenomation

Envenomation is the process by which venom is injected into some animal by the bite of a venomous animal. Many kinds of animals, including mammals , reptiles , spiders , insects , employ venom for hunting and for self defense...

.

How it works

Antibodies in the antiserum bind the infectious agent or antigen. The immune system then recognizes foreign agents bound to antibodies and triggers a more robust immune response. The use of antiserum is particularly effective against pathogens which are capable of evading the immune system in the unstimulated state but which are not robust enough to evade the stimulated immune system. The existence of antibodies to the agent therefore depends on an initial "lucky survivor" whose immune system by chance discovered a counteragent to the pathogen, or a "host species" which carries the virus but does not suffer from its effects. Further stocks of antiserum can then be produced from the initial donor or from a donor organism that is inoculated with the pathogen and cured by some stock of preexisting antiserum

Further reading

• Mupapa K, Massamba M, Kibadi K, Kuvula K, Bwaka A, Kipasa M, Colebunders R, Muyembe-Tamfum JJ. 1999. Treatment of Ebola Hemorrhagic Fever with Blood Transfusions from Convalescent Patients. The Journal of Infectious Diseases 179(suppl 1):S18-23.