The use of antipoliovirus monoclonal antibodies as an improved safety test for oral live poliomyelitis vaccine

Abstract

Almost all the individual preparations of poliovirus type 3 specific monoclonal antibodies showed high neutralizing antibody titres against low-titre Sabin type 3 virus with a titer of 10 2 CCID 50 25 μ l . However, the preparations failed to neutralize high-titre virus at a titre of about 10 7 CCID 50 25 μ l (undiluted virus fluid). The use of pooled monoclonal antibodies, comprising two or more individual antibodies, however, showed a high neutralizing activity for the high-titre virus suspension. The results indicate that the neutralization of high-titre Sabin type 3 virus can be achieved by the use of pooled monoclonal antibodies when appropriate antibodies are present. It seems likely that neutralization by these antibodies is achieved through the recognition of different neutralizing epitopes by specific antibodies. One of the safety tests used during the production of oral poliomyelitis vaccine (OPV) is that which employs type-specific antipoliovirus rabbit sera to detect adventitious viruses in monovalent poliovirus fluid. It has, however, proved difficult to prepare sera of this nature which can completely neutralize high-titre poliovirus having no cross-reactivity against other types of poliovirus. In our studies, pooled monoclonal antibodies showed a neutralizing activity against high-titre Sabin type 3 virus about 100-fold greater than that shown by rabbit antisera. Moreover, these antibodies appear to have two further important advantage for use in testing the safety of OPV: they showed no cross-neutralizing activity against heterotypic polioviruses; and they showed no evidence inhibiting the propagation of a number of viruses of monkey and human origin.