Sentence: The new primers ( C2U-C3L ) were located in the N-terminus of the S1 gene which contains hypervariabte region I ( HRV I , nucleotides , nt 142 320 ) ; this region is reponsible for induction of antibodies to the IBV that have been the basis for defining of different IBV serotypes ( 9 , 11 ). 
 Section: method