This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
MgCl2 is added to polio-vaccine because of the following 
Select and explain. 
A. Potentiates the vaccine, B. Vaccine can be kept in higher temperature, C. Preservative, D. None
B: Vaccine can be kept in higher temperature
Answer: B: Vaccine can be kept in higher temperature 
Explanation: (Vaccine can be kept in higher temperature) (491- A7th)* Molar MgCl2 protects the virus against heat inactivation* Poliovirus is resistant to ether, chloroform, bile protelytic enzymes of the intestinal contents and detergents* It is stable at PH-3* It is readily inactivated by heat (55degC for 30 minutes)* Chlorination destroys the virus in water, but organic matter delays inactivation* Phenolic disinfectants are not effective* Poliovirus does not survive lyophisation well