Alternative for the neurovirulence test.

The neurovirulence test established by Albert B. Sabin is required according to different pharmaceutical monographies (WHO Technical Report Series, US-Pharmacopoeia, European Pharmacopoeia, etc) and is used for evaluation of sufficient and consistent attenuation of life monovalent poliomyelitis virus bulk lots (Sabin) which are used for the manufacture of oral poliomyelitis vaccines (OPV). Since this animal experiment is based on the use of relatively high numbers of primates (at least 22 animals per test vaccine for the virus serotypes 1 and 2 and at least 36 animals for serotype 3) it is searched for alternatives since several years.

Alternative for the neurovirulence test.

For safety testing and release for attenuated oral poliomyelitis virus (OPV) vaccine lots, national and international authorities require the in vivo neurovirulence test (NVT). This test is extremely expensive, time consuming and is carried out in socially sensitive monkeys. In this test the test vaccine is injected into the spinal chord of monkeys and the mean lesion score of neurovirulence is evaluated and compared to that of a reference vaccine.

Increased safety level of serotype 3 Sabin oral poliomyelitis vaccine lots by improved seed virus, and tissue culture and virus infection conditions.

The content of 472U to 472C revertant virus in serotype 3 oral poliomyelitis monovalent bulk vaccines can be quantified by MAPREC (Mutant Analysis by PCR and Restriction Enzyme Cleavage). Besides other wildtype reversions identified in propagated type 3 Sabin strain populations, the 472U to 472C reversion correlates most prominently with neurovirulence in the monkey neurovirulence test. Therefore, the results can be used for the discrimination of 'good' and 'bad' vaccines on the molecular level.

Mutations in Sabin 2 strain of poliovirus and stability of attenuation phenotype.

In this study, we attempted to identify the molecular determinants in the genome of the attenuated Sabin 2 vaccine strain of poliovirus that may change during vaccine production and result in an increase in monkey neurovirulence. An extensive search for suitable vaccine lots identified six batches that had failed the monkey neurovirulence test (MNVT). On repeated tests, these batches were found to have acceptable levels of monkey neurovirulence.