Table 1.

Serum neutralization titers to CVA13, CVA15 and CVA18.

Sample group	No. sera	No. CVA13-positive (%)	No. CVA15-positive (%)	No. CVA18-positive (%)	No. CVA21-positive (%)
Commercial immune globulin	2	0 (0)	0 (0)	0 (0)	2 (100)
Melanoma	15	0 (0)	0 (0)	0 (0)	3 (20.0)
Control	6	0 (0)	0 (0)	0 (0)	0 (0.0)
Total patients	21	0	0	0	3 (14.3)

Fifteen melanoma patients were examined for serum neutralization of CVA21, CVA13, CVA15 and CVA18. Heat inactivated serum samples were diluted serially, and then titrated against 100 TCID₅₀ (CVA21, CVA13, CVA15 and CVA18) to assess neutralization status. Fifty percent neutralization scores of 1:4 or above calculated by the Karber method [19], were considered to be positive for neutralization status. Six healthy volunteers were also assessed for serum neutralizing antibodies against CVA13, CVA15 and CVA18, all of which were below 1:4 (50% neutralization score). Two commercially available immune serum globulin samples were also tested for neutralizing capacity.