[Detection of influenza B virus antibodies in different age groups using hemagglutination inhibition tests].

Antibody levels against influenza B virus were investigated by using hemagglutination-inhibition (HA-I) tests in 402 sera obtained from different age groups. Hemagglutination antigens were obtained by production of influenza B virus (B/Singapur/LLC 6201) in trypsinized Madin Darby Bovine Kidney (MDBK) cell cultured and they were used in tests. In 355 out of 402 sera (88.