TABLE 1.

Results of second passage of serum from mixed infections

Duck no.	Day of serum collection	Size of inoculum (genomes)	Fraction of DR1-13 in inoculum	No. of ducklings infected	No. of ducks with DR1-13
78	78	108	0.24	4	0
84	137	108	0.85	4	0
85	137	108	0.84	4	0
86	137	108	0.44	3	0
87	137	108	0.73	3	0
88	137	108	0.78	4	0
89	137	108	0.40	3	0