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The inhibitory effects of expression plasmids on HIV-1 replication were studied in a transient assay system. Test plasmids were co-microinjected with non-defective proviral HIV-1 DNA into a colon-carcinoma cell line (SW480) and the resulting infectious HIV-1 was quantitated after amplification in cocultivated CD4+ MT-4 cells. At a molar ratio of 1:1 and 5:1 plasmids capable of expressing a 410 bp HIV-1 fragment as antisense or sense transcript respectively both specifically inhibited HIV-1 replication up to 70%. This effect was specific for HIV-1 sequences and was not observed upon expression of unrelated RNA-segments. At a molar excess equal to or greater than 15:1, additional inhibitory effects were seen with control plasmids carrying only the strong human cytomegalovirus immediate early (HCMV IE) promoter/enhancer element. The reasons for these findings are discussed.

Summary Cloned DNA from human papillomavirus (HPV) type 16 was subjected to restriction enzyme analysis. A genome size of 7.8 ± 0.1 kb was determined and restriction maps were prepared. Fragments of HPV 16 DNA were nick-translated and hybridized with fragments of HPV 6b DNA. The two genomes appeared to be colinear. The physical state of HPV 16 DNA in genital tumours was analysed. In each of six benign tumours the viral DNA was detected exclusively as 8 kb circles. In four malignant tumours the viral DNA appeared to be integrated within the host genome but one cervical carcinoma and one case of Bowen's disease also contained oligomeric episomal molecules of viral DNA. One cervical carcinoma (WV 2965), containing only integrated viral DNA, was examined in detail. HPV 16 DNA was integrated as head-to-tail tandem repeats at more than one site. Three virus/cell junction fragments from this tumour were cloned. Two contained lengths of repetitive cellular DNA and one a length of apparently single copy cellular DNA.