young mice , vaccinated with formalin-inactivated . virus when 2 , 5 , and 7 days old , gave an immune response to such a degree that they showed ( a ) measurable peritoneal immunity which increased with small increments of age , ( b ) no cerebral resistance , and ( c ) detectable amounts of neutralizing antibody in their sera which paralleled , though at a considerably lower level , their peritoneal resistance .
C0301872
immune response
C0020964
immunity