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. 1991 Aug;65(8):4137–4141. doi: 10.1128/jvi.65.8.4137-4141.1991

The topoisomerase I inhibitor, camptothecin, inhibits equine infectious anemia virus replication in chronically infected CF2Th cells.

E Priel 1, S D Showalter 1, M Roberts 1, S Oroszlan 1, D G Blair 1
PMCID: PMC248847  PMID: 1649321

Abstract

Camptothecin (CPT), a topoisomerase I-specific inhibitor, was found in this study to inhibit the replication of equine infectious anemia virus (EIAV) in chronically infected CF2Th cells (designated CF2Th/EIAV). By measuring viral reverse transcriptase activity in the culture medium, we demonstrated that treatment for 1 h with noncytotoxic doses of this drug inhibited production by 32 to 52%, whereas continuous exposure to this drug resulted in an 85 to 92% inhibition. No effect on the viability or growth rate of the cells was detected in any of these treatments. Indirect immunofluorescence analysis of the CPT-treated CF2Th/EIAV cells with anti-p26 capsid protein antibodies showed 60 to 85% reduction in the immunofluorescence-positive cells following drug treatment, and radioimmunoprecipitation analysis of these cells showed a comparable decrease of the pr55gag precursor protein. These data suggest that CPT acts as an anti-EIAV agent to block virus replication in the chronically infected cells.

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