125I-albumin-IFN-alpha2b was prepared with the methods of Ch-T and purified with PD-10 column. The radiochemical purity was measured with TCA (trichloroacetic acid) precipitation. The antiviral activities of 125I-albumin-IFN-alpha2b and albumin-IFN-alpha2b were compared with WISH/VSV system in vitro. SD rats were injected with 125I-albumin-IFN-alpha2b subcutaneously and sacrificed at 0.5

2

6

24

48

90

180 and 300 h post-injection. Selected organs were dissected

weighed and their radioactivity was measured using γ-counter. The accumulated radioactivity in the tissues was calculated in terms of percentage of injected dose per gram organ (%ID·g-1). The labeling yield was 82.72%. The radiochemical purity of 125I-albumin-IFN-alpha2b was 95.53%

and its radioactivity was 0.26 MBq/μg. The antiviral bioactivities of albumin-IFN-alpha2b and 125I-albumin- IFN-alpha2b did not change. Biodistribution analysis of 125I-albumin-IFN-alpha2b in rats showed that concentrated 125I- albumin-IFN-alpha2b in blood reached maximum at 6 h post injection

and eliminated slowly. No specific accumulation was seen in other tissues. 125I-albumin-IFN-alpha2b could maintain in peripheral blood for a long time and it meant albumin-IFN-alpha2b would be an effective long-term interferon.