Objective: To investigate the pathological evaluation method of polio vaccine in monkey neurovirulence test by intracerebral method.
Methods: The rhesus monkeys were injected into the bilateral thalamus. After 21 days of observation, the rats were dissected. The brain and spinal cord were completely removed. After trimming, they were dehydrated and embedded. The sections were stained with HE and gallic blue and observed under a light microscope. The nerve tissue lesions were scored, and the severity of the lesions was judged according to the scores. This study involved 240 animals in 12 batches of experiments.
RESULTS: This method collected materials from different parts of the left and right brains including the needle trace, midbrain, cerebellum, pons, medulla oblongata, cervical enlargement, and lumbar enlargement. Referring to the half-section scoring method of pathological evaluation of spinal cord neurotoxicity test, The lesions of the bilateral brainstem, cervical spinal cord and lumbar spinal cord were evaluated and scored, and the degree of lesions in these three parts was determined according to the average score and combined with the specific lesions. The incidence of specific neurological lesions in this study was 15%. The incidence of various vaccine lesions was similar, with the highest proportion of mild lesions. More serious lesions are mainly seen in type III vaccines.
Conclusion: In the intracerebral neurotoxicity test, the half-section scoring method is used to score lesions, which more objectively reflects the condition of nervous system lesions. As a reference for the pathological evaluation method of polio vaccine intracerebral neurovirulence test.