This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
A heterophile antibody is found in - 
Select and explain. 
A. Weil Felix test, B. Widal test, C. Elisa, D. All
A: Weil Felix test
Answer: A: Weil Felix test 
Explanation: Ans. is 'a' i.e., Weil Felix test Heterophilic agglutination reaction o Some organisms of different class or species share closely related antigens. o When serum containing agglutinin (antibody) of one organism gives agglutination reaction with the antigen of another organism, it is called heterophilic agglutination test. Examples are o Streptococcus M.G agglutination test for primary# atypical pneumonia. o Weil - Felix reaction for typhus fever. o Paul Bunnell test for 1MN. 0 VDRL