['It is accepted that oral poliovirus vaccine (OPV) can cause vaccine-associated paralytic poliomyelitis (VAPP) and that wild poliovirus infection can rarely present as transverse myelitis. It is therefore possible that OPV could cause transverse myelitis. We previously reported a case of transverse myelitis that developed in a 6-month-old boy, 7 days after receiving his second dose of OPV.', 'Our aim was to test the virus from this patient with transverse myelitis for neurovirulence in a mouse model.', 'The TgPVR21 transgenic mouse line, which expresses the human poliovirus receptor CD155, was used to assess neurovirulence of the viruses tested. Neurovirulence was expressed as the PD(50), the dose of virus causing paralysis in 50% of the mice. Four type 3 polioviruses were tested: a prototype wild strain, a fully attenuated polio vaccine virus, a virus from a patient with VAPP and the virus from the patient with transverse myelitis.', 'The PD(50) for the wild poliovirus strain was 3.83 and for the fully attenuated vaccine strain, 7.63. The PD(50) for the two clinical isolates were between these values, > or = 4.96 for the poliovirus known to have caused VAPP and > or = 4.81 for the virus from the patient with transverse myelitis.'] Is oral poliovirus vaccine type 3 from a patient with transverse myelitis neurovirulent in a transgenic mouse model?