the demonstration that the addition of formaldehyde to the virus protein results in a simultaneous decrease of activity , of amino groups , and of groups that react with folin 's phenol reagent , and that under conditions favorable for the removal of formaldehyde the virus activity is regained and the number of such groups increases , indicates that certain of these groups play at least a partial role in the structure necessary for virus activity .
C0042736
virus protein
C0042776
virus