A virus neutralization screening test: its limitations in classifying field isolates of infectious bronchitis virus

A virus neutralization screening test using a 1:5 serum dilution of known antisera against approximately 100 embryo infective doses50 of an unknown virus was used to classify field isolates of infectious bronchitis virus. Such a test will detect the major antigen and antibody relationships. The Weakness of a screening test is that it does not quantitatively measure the minor antigen-antibody relationships between strains which would be essential to develop a classification scheme for infectious bronchitis isolates. A system of strain classification is proposed patterned after the scheme developed for the classification of the human rhinoviruses.