IMMUNOGENICITY OF TRYPSIN-TREATED TYPE-2 AND TYPE-3 POLIOVIRUS IN RATS

Oral polio vaccine will encounter the proteolytic enzyme trypsin durin g administration but inactivated polio vaccine not. To investigate the effect of trypsin on the humoral immune response, rats were immunized intramuscularly with trypsin treated type 2 and type 3 poliovirus. Ig G and IgM responses were determined as well as the neutralizing antibo dy titer. It is shown that the immunogenicity of type 2 poliovirus, un like that of type 3, is hardly affected by trypsin treatment. For type 3, trypsin treatment results in an increase in IgM and neutralizing r esponse. The IgG response decreases after trypsin treatment. The resul ts indicate that IPV formulations may be improved by the addition of t rypsin treated type 3, as suggested by Roivainen and Hovi (J Virol 198 7; 61: 3749-3753) but not by the addition of trypsin treated type 2 po liovirus.