The neutralizing characteristics of strains of infectious bronchitis virus as measured by the constant-virus variable-serum method in chicken tracheal cultures.

The constant-virus variable-serum neutralization test in chicken tracheal organ cultures was employed in cross-neutralization tests with the following infectious bronchitis viruses: Massachusetts 41, Connecticut, Iowa 97, Iowa 609, Holte, JMK, Clark 333, SE 17, Florida, and Arkansas 99. These viruses all proved serologically distinct by this method. Chickens immunized with the Connecticut strain and later challenged with Arkansas 99 were not protected against it.