Retention and expression of the left end subfragment of the herpes simplex virus type 2 BglII N DNA fragment do not correlate with tumorigenic conversion of NIH 3T3 cells.

Cotransfection experiments have been carried out using recombinant plasmids pAG60, conferring resistance to antibiotic G418, and pXho3 which contains the left end subfragment (map coordinates 0.583 to 0.596) of the transforming herpes simplex virus type 2 BglII N DNA fragment and encodes the 36K polypeptide associated with the viral ribonucleotide reductase activity. Several NIH 3T3 cell clones resistant to G418 and having morphological changes commonly observed for transformed NIH 3T3 cells were isolated and examined for the presence and stable retention of the viral sequences. Seven of the clones that retained the transfected viral sequences were analysed for the expression of the 36K polypeptide and the tumorigenic phenotype. The results gathered from these studies show that neither the retention of the viral DNA nor the expression of the 36K polypeptide correlated with tumorigenic conversion of these cells.

Sensitization of human keratinocytes to killing by parvovirus H-1 takes place during their malignant transformation but does not require them to be tumorigenic.

To investigate the antineoplastic activity of parvoviruses, proliferating normal human epidermal cells and a series of established keratinocyte cell lines derived from squamous cell carcinomas or transformed in vitro, were compared for the outcome of H-1 virus infection. All established keratinocyte cell lines were more sensitive to killing by H-1 virus than normal epidermal cells, although to varying extents. Using a step-wise procedure for malignant transformation in vitro, we found that sensitization of transformed epidermal cells to H-1 virus can be dissociated from the acquisition of a tumorigenic phenotype. Thus, spontaneously- or SV40-immortalized human keratinocytes were moderately and highly sensitive to H-1 virus, respectively, and could be made tumorigenic by Harvey-ras oncogene transfection without a major change in their susceptibility to the virus. The capacity of human keratinocytes for replicating and expressing H-1 virus DNA appears to be a revealer of cellular alterations that take place in at least some pathways to malignant transformation but that may be insufficient to confer a tumorigenic potential.

A single point mutation in the envelope gene is responsible for replication and XC fusion deficiency of the endogenous ecotropic C3H/He murine leukemia virus and for its repair in culture.

The molecular basis has been determined for differences in infectivity and XC phenotype of endogenous ecotropic murine leukemia virus of the low-leukemia mouse strain C3H/He, its relative in the high-leukemia mouse strain AKR, and highly infectious, XC-positive C3H virus variants selected in vitro. Endogenous ecotropic type C virus induced by iododeoxyuridine from the nontransformed C3H/10T1/2 cell line is XC negative and replication deficient. In contrast, viruses produced late after iododeoxyuridine induction in chemically transformed C3H/10T1/2 cells (MCA5) are XC positive and infectious. XC-negative viruses can be converted to XC-positive viruses by being grown in certain transformed cell lines. We have cloned the endogenous ecotropic provirus of C3H/He from MCA5 cells, which is XC negative and replication deficient, as well as two XC-positive C3H proviruses derived by in vitro conversion. Fragment exchange between the XC-negative molecular clone p110 and the XC-positive AKR virus clone p623 revealed that the defect in p110 lies 3' of the SalI site located in the pol region. Nucleotide sequencing established that the C3H p110 provirus was integrated within the R region of an endogenous VL30 long terminal repeat (LTR) in reverse orientation and that the virus differed from the infectious AKR p623 provirus by a point mutation, substituting Lys for Arg at the potential precursor cleavage site for gp70 and p15E. In vitro-converted XC-positive C3H proviral clones 3211 and 4211 are identical to XC-negative C3H p110, except that they have Arg at this site and the normal cleavage site is thus regenerated in these clones. The XC-negative C3H p110 was blocked in processing of Pr85env, whereas clones 3211 and 4211 had normal cleavage of the env precursor into gp70. Both the XC-negative C3H provirus and the in vitro-converted XC-positive C3H proviruses had a single copy of a 99-base-pair enhancer element in the LTR, whereas two copies of this sequence are present in the AKR proviral LTR. Substitution of Arg for Lys at the envelope precursor processing site of C3H p110 by site-directed mutagenesis is sufficient by itself to convert the virus to the XC-positive replication-competent phenotype. Thus, we have established that a single point mutation at the processing site of the envelope precursor protein Pr85 is responsible for the difference in the infectivity and XC phenotype of endogenous ecotropic murine leukemia virus from C3H/He and AKR mice and that the basis for in vitro conversion is a mutation at this site.

Disappearance and reappearance of resident macrophages: importance in C. parvum-induced tumoricidal activity.

We have investigated the role of resident macrophages in the early tumoricidal response to C. parvum. The bacteria were labeled with FITC and resident cells were labeled in situ with blue fluorescent covaspheres to enable subsequent monitoring of cellular changes by flow cytometry. Macrophages disappeared within 5 hr of administration of bacteria. At 24 hr, fibrinous adhesions containing double labeled macrophages were observed at numerous sites on the peritoneum. Macrophages associated with large numbers of bacteria, levels of beads similar to control animals, and elevated plasminogen activator-like activity did not reappear in washings in significant numbers until 72 hr. Thus, the large bacteria-containing cells that account for the majority of the early tumoricidal activity are likely to be derived from resident macrophages.

Molecular studies of human T-cell leukemia virus and adult T-cell leukemia.

We describe previously published work as well as new data on the molecular biology of human T-cell leukemia virus (HTLV) and its associated disease, adult T-cell leukemia-lymphoma (ATLL). This specific kind of disease is endemic to certain areas of Japan and the Caribbean, and several isolated cases have been described also in the United States, Israel, South America, and Africa. The disease is probably also endemic to Africa and South America, but sufficient studies of these areas have not been performed. We have molecularly cloned the HTLV genome and used the viral DNA as a probe in a large molecular study of the DNAs of human hematopoietic malignancies. The results showed that HTLV sequences could be detected in the fresh leukemic cells of all cases of ATLL tested. The neoplastic cells are of clonal origin and contain one or few copies of integrated HTLV. Detailed comparative analyses by restriction enzyme mapping of the proviral DNA in U.S., Japanese, Caribbean, and Israeli cases revealed that the viruses are almost indistinguishable. The DNA from neoplastic cells of other cases of hematopoietic neoplasias analyzed were negative for HTLV sequences with the exception of two. DNA from cells of a patient (MO) with a T-cell variant of hairy cell leukemia did contain a provirus only distantly related to HTLV (less than 10% of DNA sequence homology). The virus isolated from the MO cells has been designated HTLV-II. The second case was a patient with chronic myeloid leukemia whose cells contained exogenous DNA sequences distantly related to HTLV. Different fragments of the clones HTLV genome have been used to hybridize to DNA from uninfected normal tissues of several vertebrate species, including humans, in a search for cell-derived sequences related to the HTLV genome. No homologous sequences were found except sequences distantly related to the pol and env genes, indicating that HTLV does not carry a cellularly derived onc gene. Surprisingly, however, infection of normal human fresh T cells by HTLV transforms them into cells with permanent growth and with several other properties similar to neoplastic T cells. We have also studied the expression of viral and cellular genes in fresh and cultured neoplastic cells from patients with ATLL. Several species of viral mRNAs are always detected in the cultured neoplastic cells, whereas in some fresh samples expression of normal mRNA was not detected.(ABSTRACT TRUNCATED AT 400 WORDS)

[Isolation of cell lines transformed by highly oncogenic simian adenovirus SA7 and nononcogenic human adenovirus type 6 and their DNAs]. / Poluchenie linii kletok, transformirovannykh vysokoonkogennym adenovirusom obez'ian SA7 i neonkogennym adenovirusom cheloveka tipa 6 i ikh DNK.

Methods for generation of cell lines transformed by highly oncogenic simian adenovirus SA7, nononcogenic human adenovirus type 6 and their DNAs are described. WAG rat kidney cells were used for transformation. To produce 1 focus of transformation, 1.7 X 10(6) PFU of SA7 virus is required. Intact and fragmented DNA of both viruses may be quite effectively used for transformation. For production of 1 transformation focus 1.2 microgram SA7 DNA and 1.1 microgram type 6 adenovirus DNA is required. In most cases, DNA fragmentation increases the transforming activity which has been shown to be associated with the left genome region of both viruses under study.

Human genital cancer: synergism between two virus infections or synergism between a virus infection and initiating events?

It is proposed that human genital cancer results from a "promoting" papillomavirus infection and initiating events, frequently caused by herpes simplex virus (HSV) infections. This hypothesis is based on the demonstration of DNA from different types of papillomaviruses in some cervical cancer biopsy samples and in premalignant lesions; on studies revealing the initiator-like functions of HSV infections; and on analogous interactions of papillomavirus infections with initiators in the induction of certain animal and human carcinomas. The model reconciles seroepidemiological data linking HSV to human genital cancer with the apparent difficulties in finding HSV DNA by biopsy in genital cancer.

Temperature-dependent surface changes in cells infected or transformed by a thermosensitive mutant of polyoma virus.

Infection of BALB/3T3 cells by polyoma virus causes an alteration in the cell surface, characterized by enhanced agglutination of the cells by wheat germ agglutinin or concanavalin A. Infection by the thermosensitive mutant of polyoma, ts-3, causes the cell surface alteration at the permissive temperature, but not at the nonpermissive temperature. The cell surface alteration requires cellular DNA synthesis, but not viral DNA synthesis. BHK cells transformed by ts-3 show the surface alteration when grown at the permissive temperature, but not when grown at the nonpermissive temperature. It is concluded that the surface alteration in transformed cells is under the control of a viral gene.