TABLE 1.

Tissue section grading systems for apoptosis and histopathological damage in σ1s⁻ and σ1s⁺ reovirus-infected animals

Condition scored	Criteria for score of:
	0	1	2	3	4
Apoptosis (CNS and heart)	No caspase-3-positive cells in tissue area	Scattered caspase-3-positive cells in tissue area	Groups of caspase-3-positive cells occupying up to 30% of affected tissue area	Groups of caspase-3-positive cells found in >30% of affected tissue area
CNS histopathologya	No lesions	Affected area ≤10% of total section with morphological changes of individual dead neurons and small patchy areas of tissue destruction	Affected area approximately 10-40% of total section with partly confluent areas of tissue destruction	Affected area approximately 40-75% of total section with large confluent areas of tissue destruction	Affected area >75% of total section with total disintegration of cortical tissue, large complete areas of tissue destruction in the thalamus, and neuronal death in the hippocampus
Cardiac histopathologyb	No lesions	One or a few small lesions	Many small or a few large lesions	Multiple small and large lesions	Massive lesions

^aAs described in reference 30.

^bAs described in references 8 and 29.