Productive infection of human endometrial stromal cells by human cytomegalovirus

Cultured endometrial stromal cells were susceptible to productive human cytomegalovirus (HCMV) infection. Infection of endometrial stromal cells resulted in pronounced cytopathic effects including cell rounding and aggregation, fusions, and some lysis, although not in the synchronous fashion observed in infected fibroblasts. The aggregation events were reminiscent of normal endometrial stromal cell responses to cyclical estrogen/progesterone levels. Immunofluorescence analysis demonstrated expression of viral gene products suggesting a productive virus infection. One-step growth analysis showed that infectious virus was produced but the titers were two logs lower than those obtained in fibroblasts even though HCMV DNA accumulated to similar levels in both cell types. In contrast, viral DNA replication was greatly reduced in endometrial stromal cells immortalized with a temperature-sensitive SV40 large T gene at both permissive and nonpermissive temperatures. A more detailed analysis of viral gene expression by Northern blotting revealed earlier appearances and greater initial levels of viral transcripts in endometrial stromal cells. No HCMV gene expression was observed at 120 hpi in these cells even though half of the cells were still intact and cellular gene expression was functional. Since this was the time of peak virus production, it seems plausible that reduced viral gene expression at late times p.i. was a major contributor to the reduced titers observed in endometrial stromal cells. These in vitro results coupled with in vivo observations by others of endometritis associated with HCMV suggest that further investigation into the effects of HCMV on the endometrium is warranted.

Alteration in the coding potential and expression of H-ras in human cytomegalovirus-transformed cells

CMV-transformed cell lines demonstrated a greater level of H-ras RNA (7.5- to 9.5-fold) relative to the level for H-ras in parental cells. Nuclear run off assays showed that the RNA levels for the H-ras gene were regulated at the level of transcriptional initiation. The increased RNA levels for H-ras correlated with the level of p21rasVal-12 in transformed cells, while p21rasVal-12 was below the level of detection in nontransformed cells using Western blot analysis. In addition, an activating mutation was identified in both alleles of the first exon, codon 12 of H-ras resulting in a G:C to T:A transversion in all transformed cell lines examined in this study. These results suggest that the mutated H-ras may be one of the components by which an oncogenic phenotype is maintained in these CMV-transformed cells.

Automatic and accurate method for analysis of proteins that undergo hinge-mediated domain and loop movements

BACKGROUND

The structures of proteins that undergo significant main-chain conformational change are reported with increasing frequency. Three-dimensional atomic models are often available for two alternative conformational states of the same molecule. Inspection has shown these states to be varied in nature, arising by mechanisms that include hinge-facilitated closure between domains and smaller-scale loop motions within domains; these movements are often induced by metal ion binding or ligand binding. Polypeptides that display flexible segments are also observed in different crystal conformations or as alternatively packed subunits. Although subjective visual inspection has been previously used to compare structures and analyze conformational changes, there is a need for an objective method.

RESULTS

We have developed a straightforward, robust, and objective algorithm that can locate the residues that mediate and participate in the changes between the two conformational states. Our method does not require initial superpositioning. We illustrate the method by considering several test cases. The first example is maltose binding protein, a polypeptide that exhibits rigid-body domain closure involving multiple hinges. The second is lactate dehydrogenase, which undergoes both loop and subdomain movement; we accurately describe the location and relative magnitude of these deformations. Finally, in the example of aspartate transcarbamoylase, both hinge-mediated domain movement and functionally relevant loop rearrangements are described. In the instances in which domain closure occurs, the residues that serve as hinges between the domains involved are accurately predicted. In addition, our technique successfully identifies the exact residues that undergo intra-domain loop movements, even for movements that are accompanied by larger scale inter-domain rearrangements.

CONCLUSIONS

Our algorithm is successful in its comprehensive analysis and description of complex hinge-mediated domain motion for all structures displaying rigid-body movement and is accurate in identifying the location of any independent intra-domain rearrangements.

In vitro expression of the human cytomegalovirus DNA polymerase gene: effects of sequence alterations on enzyme activity

Genomic DNA of the Towne strain human cytomegalovirus polymerase (pol) gene (4.4-kb RsrII-NcoI segment of the EcoRI J fragment) was cloned into plasmids containing either the T3 or the T7 promoter for in vitro transcription-translation studies. The translation efficiency of unmodified pol cRNA was poor in this system and could not be improved by capping. However, the efficiency could be enhanced by replacing the leader sequence with a 40-bp AT-rich sequence derived from an alfalfa mosaic virus, R4. pol cRNA directed the synthesis of a 140-kDa polypeptide in a rabbit reticulocyte translation system. The in vitro-translated wild-type enzyme possessed significant polymerization activity which could be stimulated by salt as could that of the authentic enzyme purified from virus-infected cells. To study the critical domains of this enzyme, nine mutations were introduced into the pol gene around the conserved domains of eukaryotic polymerase by oligonucleotide-directed mutagenesis. Two constructs with mutations at amino acid residues 323 to 325 (M32QS) and 725 to 726 (M72II) remained active, with partial loss of enzyme activity, while the enzyme activities of other mutants with alterations at four domains located around amino acid residues 729 to 730 (M73HN), 804 to 807 (M80 and DE80), 910 to 913 (M91 and DE91), and 962 to 964 (M96 and DE96) were abolished. DNA template and triphosphate binding assays indicated that the mutation at 804 to 807 (conserved region III) lost the ability to bind DNA template, and four mutants, M73HN (within conserved region II), M80 (in region III), M91 (in region I), and M96 (around region V [962 to 964; amino acid sequence KKR]), failed to bind deoxyribonucleoside triphosphate. These data suggest that conserved region III is essential for DNA template binding, while residues between conserved region II and V (725 to 964) are involved in triphosphate binding.

Human cytomegalovirus immediate-early gene 2 protein interacts with itself and with several novel cellular proteins

The human cytomegalovirus immediate-early gene product 2 (IE2) is able to transactivate homologous and heterologous promoters alone or augmented by immediate-early gene product 1 (IE1). IE2 has also been shown to autoregulate the major immediate-early promoter by directly binding to a cis repression signal located between the TATA box and the cap site. However, IE2 has not been shown to act directly through a specific DNA sequence in transactivating various promoters. To understand whether IE2 can be indirectly involved in DNA sequence-specific transactivation through interactions with other transcriptional factors, we performed a study of the interactions of IE2 with cellular proteins. In order to study these interactions, IE cDNAs were subcloned into a bacterial expression vector, pGEX2T, by polymerase chain reaction amplification to produce fusion proteins which were full-length as well as proteins which contained various functional domains. We were able to demonstrate IE2's ability to interact directly or indirectly with several cellular proteins ranging from > 200 to 14 kDa through glutathione S-transferase-fusion protein precipitation and far-Western analysis. These interactions have been mapped to domains within IE2 which are known to be necessary for either transactivation or both transactivation and autoregulation. All of the IE2-associated proteins are nuclear proteins, and a subset are phosphorylated. In vitro-synthesized 35S-IE2 protein and bacterially expressed IE2 fusion proteins were used to study IE2-IE2 interaction by binding assay and far-Western analysis. IE2-IE2 interactions were mapped to a domain containing a putative helix-turn-helix motif located near the C terminus of IE2, between amino acids 456 and 539. However, IE2 was unable to directly interact with either IE1, an alternatively spliced variant of IE2 (55 kDa), or IE2 deletion mutants that did not contain the multimerization domain.

Molecular identity of a sperm acrosome antigen recognized by HS-63 monoclonal antibody

The molecular identity of mouse sperm acrosome antigen recognized by HS-63 monoclonal antibody was analyzed by various biochemical, immunological and molecular biological methods. When its cognate antigen, MSA-63 was isolated from mouse testis by immunoaffinity chromatography, a group of protein spots with wide range of molecular sizes and isoelectric points were identified. Through previous studies, it was established that most of these protein spots were actin-like molecules co-purified with MSA-63 protein from mouse testis. To analyze the molecular size heterogeneity of the isolated MSA-63 proteins, rabbit antisera against a computer-predicted antigenic synthetic peptide (amino acid residue No. 160-171) and a recombinant glutathione S-transferase (GST) fusion protein (GST-63) were raised. These two antisera and those raised against the isolated MSA-63 protein were used as the probes in comparative Western blot assay, indirect immunofluorescent assay and enzyme-linked immunosorbent assay (ELISA). Using ELISA, antisera against GST-63 and computer-predicted antigenic synthetic peptides were shown to cross-react with affinity-isolated MSA-63 protein coated on microwells. However, little immunological cross-reactivity was observed between GST-63 fusion protein and the synthetic peptide. By using a Western blot assay, two major protein bands of 22 and 32 kDa, respectively were commonly detected on mouse testis homogenate strips by both anti-MSA-63 and anti-GST-63. In addition, anti-MSA-63 also recognized several protein bands with molecular masses greater than 35 kDa. The results of this study suggested that the molecular heterogeneity of MSA-63 protein isolated from mouse testis and sperm, is due to a series of post-translational modifications on a single gene product. These modifications may include glycosylations, proteolytic digestions and tight non-covalent associations with other testicular cytoskeletal proteins, such as actins.

High rate of concurrent genital infections with human cytomegalovirus and human papillomaviruses in cervical cancer patients

A case-control study evaluated a possible association between infection with human papillomavirus (HPV) or cytomegalovirus (CMV) and cervical cancer. Seventy-eight patients with cervical cancer (cases) were compared with 55 age-compatible patients with uterine leiomyoma (controls). Genital CMV and HPV infections were diagnosed by polymerase chain reaction amplification of viral DNA in cervical tissues. Smoking, first coitus or pregnancy before age 20, multiple sex partners, history of multiple pregnancies, and frequent sexual intercourse were important factors associated with cervical cancer. Only 9% of the cases versus 29.1% of the controls did not have genital infection with either virus. Concurrent genital CMV and HPV infection was noted in 51.3% of the cases but in none of the controls. HPV infection alone occurred in 15.4% of the cases but in only 5.5% of the controls. CMV infection alone was associated with no increased risk for cervical cancer. These data suggest that a synergistic interaction may occur between these two viral infections in the oncogenesis of cervical cancer.

The role of turns in the structure of an alpha-helical protein

The turns joining segments of secondary structure have been proposed to be key elements in dictating the folded structures of native proteins. An alternative view assumes that turns play a passive role and are merely default structures that occur as a consequence of interactions between antiparallel segments of secondary structure, with chain reversal being dictated by the context surrounding the turn and not by the sequence of the turn itself. The solvent-exposure of turns and their tolerance to evolutionary variance suggests that they may have little or no effect on the formation of native structures. Previous investigations have focused on various types of beta-turns that connect antiparallel beta-strands with comparatively little reported on the structural role of interhelical turns. Here we probe the structural importance of such a turn in an antiparallel 4-helix bundle by randomly substituting an interhelical tripeptide in cytochrome b-562 with many different amino-acid sequences. Thirty-one of the resulting substituted proteins were characterized and all of them were shown to fold into stable, native-like structures. These results suggest that this interhelical turn does not does not play a dominant role in determining the folded structure of this antiparallel 4-helix bundle.

Detection of low level of human papilloma virus type 16 DNA sequences in cancer cell lines derived from two well-differentiated nasopharyngeal cancers

Human papilloma virus type 16 (HPV16) related sequences were detected in two EBV-negative nasopharyngeal carcinoma (NPC) cell lines derived from two well-differentiated NPC by polymerase chain reaction. E2 and E6 related sequences of HPV16 were demonstrated using two pairs of primers derived from these two regions. DNA sequence analysis of amplified products excluded the possibility of laboratory viral DNA contamination.

Cytomegalovirus excretion in pregnant and nonpregnant women

Cervical and urinary excretion of cytomegalovirus by Taiwanese women was identified by the presence of a cytomegalovirus-specific immediate-early gene sequence amplified by the polymerase chain reaction. Excretion rates during the first trimester of pregnancy resembled rates for nonpregnant women. As pregnancy proceeded, the cervical excretion rate increased from 13 to 40% and the urinary excretion rate increased from 1 to 13%.

Demonstration of developmental anomalies in mouse fetuses by transfer of murine cytomegalovirus DNA-injected eggs to surrogate mothers

To study the potential consequences of sperm-mediated sexual cytomegalovirus (CMV) transmission, an in vitro model of microinjection of murine CMV (MCMV) DNA into uninfected fertilized murine ova was used. After microinjected ova were cultured to blastocysts and transferred to pseudopregnant mice, the effect of the DNA on implantation and development was analyzed. At various times, the sites of implantation in the endometrium were examined. Reductions in litter size, fetal growth retardation, resorption of embryos, and fetal maldevelopment, which often involved the central nervous system, were observed. The presence of MCMV DNA sequences in DNA derived from fetuses was detected by the polymerase chain reaction followed by oligonucleotide hybridization. By in situ DNA-DNA cytohybridization and indirect immunofluorescence assays the viral sequences and antigens were localized primarily to the brain, salivary gland, and skin of maldeveloped fetuses. These results establish the potential consequences of sperm-mediated CMV transmission and induction of fetal anomalies.

Characterization of a structurally tricistronic gene of human cytomegalovirus composed of U(s)18, U(s)19, and U(s)20

A tricistronic gene mapped between 0.91 and 0.93 map units within the EcoRI D fragment of the human cytomegalovirus unique short region (U(s)) has been cloned, sequenced, and expressed in vitro. Cloned cDNAs of 2.3, 1.8, and 1.1 kb derived from this region were isolated from a lambda gt11 cDNA library made from virus-infected fibroblasts and used for this study. Two major classes of 3'-coterminal mRNAs, 2.8 and 1.1 kb, were transcribed from this region. Sequence analysis of the cDNAs and the upstream genomic DNA revealed three open reading frames (ORFs), U(s)18, U(s)19, and U(s)20, and a common polyadenylation signal located 15 bases upstream of the poly(A) tail of both the 2.85- and 1.1-kb mRNAs. Protein structure analyses predicted the existence of multiple hydrophobic moieties, suggesting that the U(s)18, U(s)19, and U(s)20 polypeptides were transmembrane proteins. The major transcription initiation site, determined by primer extension and S1 nuclease mapping, for the 2.85-kb transcript was located right at the first initiation codon of the U(s)20 ORF. There was no typical TATA box or CAAT box upstream of the 2.85-kb mRNA cap site except for a TATAAGA sequence that was found about 210 bp downstream from the major cap site. The 1.1-kb transcript was initiated 33 bp upstream of the U(s)18 translation initiation site, and an atypical TATA box sequence (GATAAGA) was found 22 bp upstream of the transcription start site. Differences in transcription kinetics and sensitivities to metabolic inhibitors suggest that they were regulated by different mechanisms; the 2.85-kb mRNA belongs to the early (beta) class of transcripts, while the 1.1-kb mRNA is a late (gamma) message. Subgenomic DNA segments derived from the U(s)18, U(s)19, and U(s)20 ORFs were subcloned and overexpressed in Escherichia coli as fusion proteins with glutathione-s-transferase. Western immunoblot analysis with antibodies against the U(s)18, U(s)19, and U(s)20 fusion proteins detected virus-specific polypeptides with molecular sizes of 36, 32, and 43 kDa, respectively. All three antibodies also exhibited a positive immunofluorescence reaction with human cytomegalovirus-infected cells harvested at late stages of infection.

Dimerization of NF-KB2 with RelA(p65) regulates DNA binding, transcriptional activation, and inhibition by an I kappa B-alpha (MAD-3)

Inducible expression of human immunodeficiency virus (HIV) is regulated by a cellular transcription factor, nuclear factor kappa B (NF-kappa B). NF-kappa B is composed of distinct subunits; five independent genes, NFKB1(p105), NFKB2(p100), RelA(p65), c-rel and relB, that encode related proteins that bind to kappa B DNA elements have been isolated. We have previously found that NFKB2(p49/p52) acts in concert with RelA(p65) to stimulate the HIV enhancer in Jurkat T-leukemia cells. Here we examine the biochemical basis for the transcriptional regulation of HIV by NFKB2. Using Scatchard analysis, we have determined the dissociation constants of homodimeric p49 and heterodimeric p49/p65 for binding to the HIV kappa B site. p49 has a approximately 18-fold-lower affinity for the HIV kappa B site (KD = 69.1 pM) than does the approximately 50-kDa protein NFKB1(p50) derived from p105 (KD = 3.9 pM). In contrast, the affinity of heterodimeric NFKB2(p49)/RelA(p65) for this site is approximately 6-fold higher (KD = 11.8 pM) than that of p49 alone. Consistent with these findings, in vitro transcription was stimulated 18-fold by the addition of preformed, heterodimeric NFKB2(p49)/RelA(p65) protein. Transcriptional activation of the HIV enhancer was also subject to regulation by recently cloned I kappa B-alpha(MAD-3). Recombinant I kappa B-alpha(MAD-3) inhibited the DNA binding activity of p65, p49/p65, and p50/p65 but stimulated the binding of NFKB2(p49) or NFKB1(p50). Functional activation of an HIV reporter plasmid by p49/p65 in transiently transfected Jurkat T-leukemia cells was also inhibited by coexpression of MAD-3. These data suggest that binding of the NFKB2 subunit to the HIV enhancer is facilitated by RelA(p65) and that this NFKB2(p49)/p65 heterodimeric complex mediates transcriptional activation which is subject to regulation by MAD-3.

Multiple mechanisms are implicated in the regulation of NF-kappa B activity during human cytomegalovirus infection

Infection-induced activation of the human cytomegalovirus major immediate early enhancer/promoter has been shown to be regulated primarily by transcription factor NF-kappa B cis elements. However, the mechanism(s) by which human cytomegalovirus induces NF-kappa B activity is unknown. A study was therefore undertaken to determine how this virus would affect normal NF-kappa B regulation. Viral infection of fibroblasts resulted in the specific stimulation of promoters containing major histocompatibility complex NF-kappa B cis elements fused upstream of the chloramphenicol acetyltransferase reporter gene. Electrophoretic mobility shift assays of nuclear extracts derived from mock- and virus-infected cells showed dramatic and sustained increases in DNA-binding proteins specific for these NF-kappa B sequences. Experiments using MAD-3 I kappa B, a specific inhibitor of NF-kappa B, and antibodies directed against rel family members demonstrated that the induced binding activities contained p50 and p65 proteins but not c-rel. Northern analysis indicated maximal levels of p50 mRNA by 4 h postinfection, whereas p65 and MAD-3 I kappa B mRNA accumulation peaked at 48-72 h postinfection, suggesting different regulatory mechanisms for p50 and p65/I kappa B genes. Electrophoretic mobility shift assays with deoxycholate-treated cytoplasmic extracts demonstrated a 3- to 4-fold decrease in the cytosolic stores of NF-kappa B binding activity by 4 h postinfection. Western blots probed with antibodies directed against MAD-3 I kappa B or pp40 (a protein isolated from chicken with sequence and biochemical properties similar to those of MAD-3 I kappa B) indicated that a cross-reactive peptide of 39 kDa was no longer detectable after 24 h postinfection. These results demonstrate that the activation and maintenance of nuclear NF-kappa B DNA binding and enhancer activities upon human cytomegalovirus infection occurs by multiple mechanisms.

Cytomegalovirus transmission in special-care centers for mentally retarded children

This study aimed to determine whether special-care centers for mentally retarded children are high-risk settings for cytomegalovirus (CMV) transmission. Serum and urine specimens obtained from 311 mentally retarded children aged 3 to 12 in three centers were compared for CMV seropositivity and CMV viruria with specimens from 360 normal children of the same ages. A seropositivity rate of 73.5% and a viruria rate of 8.7% were found among the children attending special-care centers. These rates were significantly higher than the 59.2% seropositivity and 1.7% viruria found among normal children. By logistic regression analysis, it was shown that the prevalence of CMV viruria in the class/center was one of the most important determinants for acquiring CMV infection. The data suggest that acquisition of CMV from playmates or classmates occurs frequently in special-care centers and that horizontal transmission of virus is the most plausible explanation for the higher prevalence of CMV infection among mentally retarded children.

Induction of NF-kappa B-like activity by platelet-derived growth factor in mouse fibroblasts

Nuclear factor kappa B (NF-kappa B) modulates the expression of numerous genes via interaction with a specific DNA sequence termed the kappa B site. Its activity is modulated by a cytosolic inhibitor protein termed I kappa B, and its activation occurs in response to a variety of agents in a variety of cell types, most notably B and T lymphocytes. Data presented here show that an activity (designated complex I) that binds specifically to the kappa B site is induced in density-arrested Balb/c-3T3 mouse fibroblasts by platelet-derived growth factor (PDGF), a potent mitogen for these cells. Increased levels of complex I, as evaluated by electrophoretic mobility shift assays of nuclear extracts, were observed in cells treated for 1-4 h (but not 15 min) with the BB isoform of PDGF. 12-O-tetradecanoylphorbol 13-acetate (TPA) and the AA isoform of PDGF also stimulated this response and both isoforms, but not TPA, were effective in cells depleted of protein kinase C. Complex I most likely is authentic NF-kappa B, a p50-p65 heterodimer, or a closely related factor because it exhibited properties characteristic of those previously described for NF-kappa B including inducibility by deoxycholate and cycloheximide and sensitivity to I kappa B. A second kappa B binding activity (complex II), which apparently contained p50 homodimers, displayed limited induction by PDGF, whereas a third complex (complex III) migrated faster than but behaved similarly to complex I. These studies suggest that NF-kappa B or an NF-kappa B-like factor may participate in the expression of PDGF-inducible genes.

E2F mediates dihydrofolate reductase promoter activation and multiprotein complex formation in human cytomegalovirus infection

The adenovirus immediate-early protein E1A activates the adenovirus E2 promoter and several cellular gene promoters through transcription factor E2F. The immediate-early proteins of human cytomegalovirus (HCMV) can complement an E1A-deficient adenovirus mutant and activate the adenovirus E2 promoter. HCMV also has been shown to activate the adenovirus E2 promoter. On the basis of these findings, we have investigated whether HCMV can activate the promoter of the cellular dihydrofolate reductase (DHFR) gene, which requires E2F binding for maximal promoter activity. We show that HCMV activates the DHFR promoter and that products of the HCMV major immediate-early gene region mediate the activation of the promoter specifically through the E2F site. We used gel mobility shift assays to search for potential molecular mechanisms for this activation and found an "infection-specific" multimeric complex that bound to the E2F sites in the DHFR and E2 promoters in extracts from HCMV-infected cells but not in extracts from uninfected cells. Several antibodies against HCMV immediate-early gene products had no effect on this infection-specific complex. Subsequently, the complex was found to contain E2F, cyclin A, p33cdk2, and p107 and to be similar to S-phase-specific complexes that recently have been identified in several cell types. A functional role for the binding of the cyclin A-p33cdk2 complex to cellular gene promoters has yet to be demonstrated; however, HCMV infection causes the induction of both cellular DNA replication and transcription of growth-related genes containing E2F sites in their promoters. The findings described above therefore may relate to both of these effects of HCMV infection. We also provide evidence that some of the molecular events associated with adenovirus infection are different from those associated with HCMV infection.

Polymerase chain reaction to detect human cytomegalovirus in livers of infants with neonatal hepatitis

Neonatal hepatitis is closely related to human cytomegalovirus infection in Taiwan, a conclusion based on serological and urine culture studies. To obtain more direct evidence further relating cytomegalovirus to the pathogenesis of neonatal hepatitis, the cytomegalovirus genome was studied in the liver tissues of 50 infants with neonatal hepatitis using the polymerase chain reaction (PCR). Liver tissues from 26 infants with biliary atresia and another 30 infants and children with diagnoses other than neonatal hepatitis, cholestasis, or hepatitis were also studied for comparison. Sequences from the immediate early gene 1 and 2 regions were used as primers. The liver tissues from 23 (46%) of the 50 infants with neonatal hepatitis were positive for cytomegalovirus genome, whereas those of 2 of the 26 infants with biliary atresia and none of the liver tissues from 30 infants and children without neonatal hepatitis were positive for cytomegalovirus genome, by PCR. The results of PCR correlated well with that of serology and urine culture. This study provides further evidence of cytomegalovirus in the pathogenesis of neonatal hepatitis.

Seroepidemiology of cytomegalovirus infection among children between the ages of 4 and 12 years in Taiwan

To determine risk factors responsible for primary cytomegalovirus (CMV) infection in Taiwan, samples of blood for antibody to CMV were obtained from 362 children aged 4 to 12 years: 58% were found to be positive for anti-CMV IgG antibody. Logistic regression analysis showed that seropositivity correlated with age, method of delivery, duration of breast feeding, and younger age of mother. Neither socioeconomic status nor crowded living conditions showed significant correlation with CMV seropositivity. Primary CMV infection in Taiwan appears to be less related to socioeconomic status shown in western countries, and, since the majority of pregnant women were seropositive in Taiwan, two of the major sources of primary CMV transmission are infected breast milk and the infected genital tract.

Characterization of human cytomegalovirus UL84 early gene and identification of its putative protein product

The DNA sequence and transcription pattern of human cytomegalovirus early gene UL84 were analyzed. This gene was mapped within a 2.6-kb PstI fragment located between 0.534 and 0.545 map unit of the large unique segment of the human cytomegalovirus genome, which is adjacent to the pp65 and pp71 genes. A 2.0-kb mRNA was transcribed from this region in the same leftward direction as the mRNAs of the pp65 and pp71 genes. The message was first detected at 2.5 h postinfection and reached a maximal level between 72 and 96 h postinfection. The nucleotide sequences of the 2.6-kb PstI genomic DNA fragment and the cDNA derived from this region were determined. The resulting data revealed a polyadenylation signal (AATAAA) located 14 nucleotides upstream from the poly(A) tail of the cDNA and a 1,761-bp open reading frame capable of encoding a 65-kDa polypeptide. A potential leucine zipper was found in the N-terminal half of the peptide molecule between amino acids 114 and 135. In addition, a different periodic leucine repeat with leucine at every eighth position was found between amino acids 325 and 373. The transcriptional initiation site of this early gene was determined by primer extension analysis. A putative TATA box (TATTTAA) located 24 bp upstream of the cap site and several inverted repeats were found in the region further upstream of the TATA box. To test whether the open reading frame of this cDNA encodes a virus-specific protein, the cDNA was overexpressed in Escherichia coli as a fusion protein used to generate antibodies in rabbits. A protein with a molecular size of 65 kDa was detected in the infected-cell extracts harvested at 6 to 72 h postinfection, but not in purified virions, using immunoblot analysis. Both nuclear and cytoplasmic fluorescences were found at late stages of virus infection. From the results obtained, we postulate that UL84 may be a stable, virus-specific, nonstructural protein capable of forming a homo- or heterodimeric molecule.

Irreversible inhibition of human cytomegalovirus replication by topoisomerase II inhibitor, etoposide: a new strategy for the treatment of human cytomegalovirus infection

We demonstrated previously that human cytomegalovirus (CMV) infections could enhance the expression of cellular topoisomerase II and this enzyme activity is essential for CMV to replicate in vitro (Benson and Huang, 1988; Benson and Huang, 1990). In this study, we further show that in addition to m-AMSA and VM26 which we had previously reported, a widely used and clinically available drug, etoposide (VP-16 or VePesid) can irreversibly inhibit CMV replication at the drug concentration (2.5 micrograms/ml) greatly below toxic levels to stationary phase cells. Growing cells were more sensitive to etoposide than stationary phase cells and slight growth inhibition occurred at 2.5 micrograms/ml level. This inhibitor does not prevent the expression of CMV immediate-early and early genes, but can inhibit viral DNA and late viral-proteins synthesis. Because of their irreversible inhibitory effects and approval usage in clinical oncology, it is suggested that this group of compounds, particularly etoposide (VP-16), can be used to control life-threatening CMV infections, such as CMV pneumonitis and CMV retinitis, in cancer and immunocompromised patients or patients with AIDS.

Oncogenic transformation by cellular DNA isolated from human cytomegalovirus-infected cells

Delayed replication of human cytomegalovirus (CMV) was initiated in human embryonic fibroblasts using partially ultraviolet light-inactivated virus stock. Cellular [high molecular weight (HMW)] DNA extracted from CMV-infected cell cultures demonstrated a substantial increase in transforming activity after introduction into hamster embryo fibroblasts relative to HMW DNA extracted from mock-infected cells. The transforming activity of HMW DNA varied between 0.01 and 0.25 foci/micrograms DNA. HMW DNA isolated from CMV-infected cells after initiation of viral DNA synthesis demonstrated a significant decrease in the induction of morphologically transformed foci. The transforming activity of HMW DNA was unaffected by HindIII or XbaI endonuclease digestion, but it was sensitive to sonication and EcoRI endonuclease and DNase treatment. Six cell lines were established from the foci of morphologically altered cells. Cells of these lines demonstrated loss of contact inhibition, replication in semisolid agarose or in medium containing low serum, a high saturation density, and tumorigenicity when implanted into hamsters. Histopathological examination of the tumors identified the tissues as fibrosarcomas. In situ hybridization of cells isolated from foci of morphologically altered cells or Southern blot analysis of DNA isolated from either the cell lines or tumors did not demonstrate the presence of sequences with homology to viral DNA using the transforming region or the entire viral DNA as a probe. The lack of viral DNA sequences as well as the similar phenotypic characteristics of cell lines and tumors suggest that alteration(s) induced by CMV may occur in specific region(s) of cellular DNA.

Stable expression of functional human cytomegalovirus immediate-early proteins IE1 and IE2 in HeLa cells

The major immediate-early (IE) genes 1 and 2 of human cytomegalovirus (HCMV) encode proteins that regulate the expression of HCMV genes as well as some other viral and cellular genes. In order to study the expression and function of these IE gene products, we established several HeLa cell lines that stably expressed the 68-kD IE1 protein, the 82-kD IE2 protein, or both proteins. The IE proteins expressed in these cell lines were biologically active, as shown by transient chloramphenicol acetyltransferase assays. Transcription from the major IE promoter was augmented in the IE1-expressing cells, while transcription from the HCMV early gene UL84 promoter was activated in the IE2-expressing cells. In addition, we found that the IE2-expressing cells established colonies in soft agarose more efficiently than the parental HeLa and the IE1-expressing cells. Furthermore, expression of both the IE1 and IE2 proteins was increased by treatment of these cell lines with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. Thus, our cell lines provide a useful system to study the regulation of IE gene expression in human cells as well as to study transaction by HCMV IE proteins on various viral and cellular genes.

Human cytomegalovirus induces expression of cellular topoisomerase II

Previous work from our laboratory has suggested that topoisomerase II is required for replication of human cytomegalovirus (HCMV). In assays of confluent human embryonic lung cells infected with HCMV, topoisomerase II inhibitors exhibited an irreversible inhibition of viral DNA replication. However, Northern (RNA blot) and Western (immunoblot) analyses of confluent uninfected human embryonic lung cells detected very low levels of cellular topoisomerase II RNA and protein. Quantitation of human topoisomerase II RNA and protein levels at various times after HCMV infection revealed that HCMV induces increased intracellular levels of both topoisomerase II RNA and protein. Such accumulation began at early times of infection, continued through late in infection, and was not reduced by inhibition of viral DNA synthesis. This is the first report of such induction by a viral infection. Topoisomerase II was also detected in isolated HCMV virions.

Disparate effects of two herpesvirus [corrected] immediate-early gene trans-activators on the HIV-1 LTR

The BMLF1 region of the Epstein-Barr virus (EBV) genome and the immediate-early (IE) region of human cytomegalovirus (HCMV) both encode proteins which can trans-activate heterologous promoter/chloramphenicol acetyl transferase (CAT) constructs, including a human immunodeficiency virus type-1 promoter/CAT construct. We demonstrate here that this trans-activation by the EBV BMLF1 gene product, which we have previously shown to be largely post-transcriptional, is reporter gene dependent. In contrast, trans-activation by the HCMV-IE gene product(s), previously shown to be mediated at the RNA level, is seen regardless of whether CAT, human growth hormone, or beta-galactosidase is used as the reporter gene. Mutational analysis revealed no specific cis-acting sequences within the HIV-1 promoter which were required for trans-activation by the HCMV-IE gene product(s).

Cytomegalovirus infection stimulates expression of monocyte-associated mediator genes

Monocytes and tissue macrophages play important roles in host defense against virus infections and, in the case of human cytomegalovirus (HCMV) and HIV, may also be the reservoir for latent disease. Because these cells can also rapidly respond to most infections by secretion of inflammatory mediators, we were interested in determining if HCMV infection could have a direct activating effect on macrophage cytokine production. To do this, we primarily investigated the influence of HCMV infection on IL-1 beta-mRNA expression in peripheral blood monocytes and the promyelocytic cell line, ML-3 as well as the inflammatory response genes TNF-alpha, MAD-9, MAD-6, and MAD-2 in the promyelocytic ML-3 cell line. Exposure of ML-3 cells to the virus prior to induction of differentiation had little influence on mediator gene expression. However, induction of the macrophage phenotype by pretreatment of ML-3 cells with the phorbol ester, PMA, followed by HCMV challenge, resulted in a greatly extended period of expression of IL-1 beta, TNF-alpha, MAD-9, and CSF-1 but not MAD-6 and MAD-2. Constitutively expressed genes such as lysozyme and actin were not similarly modulated. Both RNA dot-blot and in situ hybridization studies demonstrated that infection of human peripheral blood monocytes with HCMV leads to sustained expression of IL-1 beta mRNA for up to 96 h, which contrasted markedly with mock-infected or LPS-stimulated monocytes. Flow cytometric analysis of the intracellular levels of IL-1 beta protein in ML-3 cells indicated that not only was there more protein produced in infected cells, but that the majority of the cells had responded. Enhanced levels of the intracellular form of IL-1 beta in monocytes was confirmed by Western blot analysis. Cotransfection experiments were performed using IL-1 beta-CAT chimeric plasmids together with plasmids encoding HCMV-immediate-early gene region products. Transactivation of the IL-1 beta gene by region 2 of the immediate-early gene was observed in ML-3 cells that had been induced to differentiate prior to transfection. No stimulation of IL-1 beta promoter activity was observed in ML-3 cells that were undifferentiated prior to transfection. In summary, HCMV infection, although not leading to productive infection, nonetheless may contribute to the pathology of the infection through enhancement of monocyte inflammatory mediator gene expression with subsequent stimulation of protein synthesis.

Cytomegalovirus infection stimulates expression of monocyte-associated mediator genes

Monocytes and tissue macrophages play important roles in host defense against virus infections and, in the case of human cytomegalovirus (HCMV) and HIV, may also be the reservoir for latent disease. Because these cells can also rapidly respond to most infections by secretion of inflammatory mediators, we were interested in determining if HCMV infection could have a direct activating effect on macrophage cytokine production. To do this, we primarily investigated the influence of HCMV infection on IL-1 beta-mRNA expression in peripheral blood monocytes and the promyelocytic cell line, ML-3 as well as the inflammatory response genes TNF-alpha, MAD-9, MAD-6, and MAD-2 in the promyelocytic ML-3 cell line. Exposure of ML-3 cells to the virus prior to induction of differentiation had little influence on mediator gene expression. However, induction of the macrophage phenotype by pretreatment of ML-3 cells with the phorbol ester, PMA, followed by HCMV challenge, resulted in a greatly extended period of expression of IL-1 beta, TNF-alpha, MAD-9, and CSF-1 but not MAD-6 and MAD-2. Constitutively expressed genes such as lysozyme and actin were not similarly modulated. Both RNA dot-blot and in situ hybridization studies demonstrated that infection of human peripheral blood monocytes with HCMV leads to sustained expression of IL-1 beta mRNA for up to 96 h, which contrasted markedly with mock-infected or LPS-stimulated monocytes. Flow cytometric analysis of the intracellular levels of IL-1 beta protein in ML-3 cells indicated that not only was there more protein produced in infected cells, but that the majority of the cells had responded. Enhanced levels of the intracellular form of IL-1 beta in monocytes was confirmed by Western blot analysis. Cotransfection experiments were performed using IL-1 beta-CAT chimeric plasmids together with plasmids encoding HCMV-immediate-early gene region products. Transactivation of the IL-1 beta gene by region 2 of the immediate-early gene was observed in ML-3 cells that had been induced to differentiate prior to transfection. No stimulation of IL-1 beta promoter activity was observed in ML-3 cells that were undifferentiated prior to transfection. In summary, HCMV infection, although not leading to productive infection, nonetheless may contribute to the pathology of the infection through enhancement of monocyte inflammatory mediator gene expression with subsequent stimulation of protein synthesis.

1,25-Dihydroxyvitamin D3 silences 3',5'-cyclic adenosine monophosphate enhancement of somatostatin gene transcription in human thyroid C cells

Treatment of the somatostatin (SRIF)-producing TT cell line with 1,25 dihydroxyvitamin D3 (1,25 D3) lowered intracellular SRIF mRNA and peptide concentration. In separate experiments, the cAMP analog 8-(4-chlorophenylthio)-cAMP stimulated a rapid increase in SRIF mRNA content of the TT cells and SRIF peptide secretion. To determine whether 1,25 D3 could inhibit either the transcriptional or secretory effects of cAMP, TT cells were pretreated with 1,25 D3 for 4 days followed by treatment with the cAMP analog. Pretreatment with 1,25 D3 inhibited the cAMP-mediated increase of SRIF mRNA, but had no effect on the secretory response. We conclude that the ability of 1,25 D3 to silence SRIF gene expression is more potent than cAMP enhancer activity but that 1,25 D3 has no effect on that portion of the cAMP-dependent pathway which regulates peptide secretion.

The febrile father with a cytomegalovirus infection. A family affair

Existing evidence has convincingly established that young children often transmit cytomegalovirus (CMV) infection to their parents. What proportion of these parental infections lead to clinical disease is unknown, but this sequence of events is probably not rare. Physicians seeing young adults with prolonged but otherwise nondescript febrile illness should inquire about the presence of young children in the household. Parental CMV infection is not limited to parents whose children attend day-care centers or are cared for in neonatal intensive care units. As in our case of the febrile father, it may be strictly a family affair.

Two specific topoisomerase II inhibitors prevent replication of human cytomegalovirus DNA: an implied role in replication of the viral genome

In this study, we show that human cytomegalovirus DNA synthesis is inhibited in infected confluent human embryonic lung cells treated with the DNA-intercalative topoisomerase II inhibitor 4-9'-(acridinylamino)methanesulfon-m-anisidide (m-AMSA). Similar inhibitory effects were observed with VM-26, a nonintercalative topoisomerase II inhibitor. This antiviral effect is not attributable to cytotoxic effects per se. Furthermore, m-AMSA appears to have a notably irreversible inhibitory effect on human cytomegalovirus DNA replication. No inhibition of viral DNA synthesis was observed with o-AMSA, a DNA-intercalative isomer of m-AMSA that does not inhibit topoisomerase II.

Cytomegalovirus infection and viral-induced transformation of human endothelial cells

Human cytomegalovirus (CMV) has been associated with vascular pathology. In vivo, CMV is present in vessel wall cells during acute and chronic infections as well as in atherosclerotic lesions. CMV nucleic acids and proteins have also been detected within Kaposi's sarcoma lesions. Because of these associations, we studied the interaction of CMV with human endothelial cells with particular attention to its oncogenicity in this cell type. Our data demonstrate that human endothelial cells are permissive to viral replication but that the viral replication cycle is delayed compared with fibroblast cells. Persistent infections can result with minimal cytopathology. CMV can transform these cells to anchorage-independent growth, and noninfectious virus is still capable of inducing this transforming event. Our results demonstrate that productive or persistent CMV infection of endothelial cells and viral-induced transformation can occur, thus providing an in vitro correlate of in vivo events.

Insertion and extension of acyclic, dideoxy, and ara nucleotides by herpesviridae, human alpha and human beta polymerases. A unique inhibition mechanism for 9-(1,3-dihydroxy-2-propoxymethyl)guanine triphosphate

The ability of human alpha and beta DNA polymerases and herpes simplex virus type 2 (HSV-2) and human cytomegalovirus (HCMV) DNA polymerases to insert and extend several nucleotide analogs has been investigated using a variation of Sanger-Coulson DNA sequencing technology. The analogs included the triphosphates of two antiviral nucleosides with incomplete sugar rings: 9-(1,3-dihydroxy-2-propoxymethyl)guanine (dhpG) and 9-(2-hydroxyethoxymethyl)guanine (acyG or acyclovir), as well as dideoxy and arabinosyl nucleoside triphosphates. Three pairs of contrasting behaviors were found, each pair distinguishing the two human polymerases from the two viral ones: first, extension behavior with araNTPs; second, insertion/extension behavior with dhpGTP; and third, the relative preference for insertion of ddGTP versus acyGTP. The relative level of insertion of the nucleotide analogs by HCMV and HSV-2 DNA polymerases was dhpGTP greater than (acyGTP and araNTP) greater than ddGTP, whereas by human alpha polymerase it was araATP greater than ddGTP much greater than (acyGTP and dhpGTP) and by human beta polymerase it was (araATP and ddGTP) much greater than (acyGTP and dhpGTP). Evidence is presented for three mechanisms of inhibition by extendible nucleotides (of dhp and ara types) exhibiting frequent internalization: araATP acted as a simple pseudoterminator of alpha and beta polymerases, but was easily extended past singlet sites by Herpesviridae polymerases and only stalled at sites requiring two or more araATP insertions in a row. Herpesviridae polymerases stalled after adding dhpGMP and one additional nucleotide, suggesting that polymerase translocation problems may be a factor in polymerase inhibition by modified sugar nucleotide analogs. The amino acid sequence of the human alpha DNA polymerase, which is acyGTP resistant, was found to vary by one amino acid from the amino sequences of the Herpesviridae polymerases in a region of significant similarity and probable functional homology. Amino acid differences at that same site differentiate acyclovir-resistant HSV-1 mutants from the acyclovir-sensitive HSV-1 wild type.

Transfer and expression of plasmids containing human cytomegalovirus immediate-early gene 1 promoter-enhancer sequences in eukaryotic and prokaryotic cells

The human cytomegalovirus immediate-early gene region 1 promoter-enhancer is active in bacteria and in many mammalian cells. Recombinant plasmids containing portions of this DNA can be used to promote the expression of foreign proteins in many cells. In this communication, we report the optimal conditions for transfer of plasmid DNA to cells by electroporation and the transient expression assays which document the activity of different promoter constructions. The observed activity of the human cytomegalovirus promoter is more than 100-fold higher than the activity of the early promoter of SV40.

Immediate-early gene region of human cytomegalovirus trans-activates the promoter of human immunodeficiency virus

Almost all homosexual patients with acquired immunodeficiency syndrome are also actively infected with human cytomegalovirus (HCMV). We have hypothesized that an interaction between HCMV and human immunodeficiency virus (HIV), the agent that causes acquired immunodeficiency syndrome, may exist at a molecular level and contribute to the manifestations of HIV infection. In this report, we demonstrate that the immediate-early gene region of HCMV, in particular immediate-early region 2, trans-activates the expression of the bacterial gene chloramphenicol acetyltransferase that is fused to the HIV long terminal repeat and carried by plasmid pHIV-CAT. The HCMV immediate-early trans-activator increases the level of mRNA from the plasmid pHIV-CAT. The sequences of HIV that are responsive to trans-activation by the HCMV immediate-early region are distinct from HIV sequences that required for response to the HIV tat. The stimulation of HIV gene expression by HCMV gene functions could enhance the consequences of HIV infection in persons with previous or concurrent HCMV infection.

The effect of 1,25-dihydroxyvitamin D3 treatment on calcitonin and calcitonin gene-related peptide mRNA levels in cultured human thyroid C-cells

We utilized the TT cell, a human C-cell line derived from a medullary thyroid carcinoma, to study the effects of 1,25-dihydroxyvitamin D3 on cell growth and expression of the calcitonin gene. The growth rate of cells treated for 8 days with 1,25-dihydroxyvitamin D3 did not differ significantly from control or 24,25-dihydroxyvitamin D3 treated cells. Total RNA was isolated, and calcitonin and calcitonin gene-related peptide (CGRP) levels were measured by hybridization. 1,25 D3 lowered calcitonin and CGRP mRNA levels in a time- and dose-dependent fashion; 24,25 D3 had no effect. Northern blots revealed a decrease in the mature mRNA as well as the common precursor forms, indicating a transcriptional effect of 1,25 D3.

Alteration of protein phosphorylation patterns in cell lines morphologically transformed by human cytomegalovirus

Human fibroblastic cell lines morphologically transformed by either live virus or DNA fragments of human cytomegalovirus had altered plasma membrane protein composition; quantitative changes, and gains and losses in protein composition in comparison to normal parent cell lines were detected. These transformed cell lines showed altered total cell protein phosphorylation patterns when compared to parent cell lines. A two to four fold increase in in vivo protein phosphorylation at serine and threonine residues was observed; no increase in phosphorylation at total cell tyrosine residues was detected. Analysis of the in vivo phosphorylated protein by two dimensional gel electrophoresis revealed some similarities as well as differences in the types of polypeptides phosphorylated between transformed and control cell lines. Increased (two-to sixfold over parent cell extracts) casein kinase and polyamine dependent casein kinase activities were detected in HCMV transformed cell extracts.

Early-stage developmental abnormalities induced by murine cytomegalovirus

The onset of the effects of murine cytomegalovirus (MCMV) infection on an early stage of embryonic development (nine days) in a mouse model was studied with the aid of scanning electron microscopy. MCMV was injected into the endometrial lumina of pregnant mice at the time of implantation. The mice were later killed, and sites of embryonic implantation were examined. Compared with uninfected mice and mice inoculated with heat-inactivated virus, litter sizes were reduced, and the incidence of abnormal fetuses was significantly increased among MCMV-infected animals. Scanning electron microscopy also revealed maldeveloped cranial regions characterized by an unclosed neural tube and severely underdeveloped head. Ectodermal abnormalities, including poxlike formations and ballooning cells, were observed in several embryos. Thus, early cytomegalovirus infection may not only result in fetal loss, but may also interfere with the process of morphogenesis.

Murine cytomegalovirus infection of mouse testes

With the aim of illustrating a mechanism of cytomegalovirus (CMV) venereal transmission, we induced murine CMV infection in the mouse testes of immunologically competent mice. Using in situ cytohybridization, we were able to show that murine CMV-specific DNA was associated with spermatocytes and mature sperm. Electron microscopy studies also supported sperm infection. The virus could be reisolated from infected epididymal sperm by cocultivation with mouse embryo fibroblasts. We found no difference in either the sexual performance or the fertilization efficiency of the sperm between infected and uninfected males.

Anti-estrogenic action of chlordecone in rat pituitary gonadotrophs in vitro

Estradiol-17 beta (E2) enhances the response of rat pituitary gonadotrophs to gonadotrophin-releasing hormone (GnRH) in vitro. This effect of E2 on rat gonadotrophs in vitro was applied as a model to study the estrogenic or anti-estrogenic activity of chlordecone in gonadotrophs. Rat pituitary cell cultures were treated with E2 (10(-10) M), chlordecone (10(-7) to 10(-5) M), or both before a 6-hr challenge of D-Lys6-GnRH (GnRH-A). Secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) during the 6-hr of GnRH-A treatment was measured. Pretreatment of cells with E2 for 2 days increased the GnRH-A-stimulated LH and FSH secretion approximately twofold. This effect of E2 was antagonized by the coexistence of chlordecone in a dose-dependent manner. The effect of E2 (10(-10) M) could be totally abolished by 10(-6) M chlordecone. Further, chlordecone alone had little or no effect on basal secretion of LH and FSH, but it significantly suppressed the response of gonadotrophs to GnRH-A. [Mirex, a compound with a similar chemical structure to chlordecone, did not suppress GnRH-A-stimulated secretion of LH or FSH under any condition tested.] The present study demonstrated that chlordecone had two specific effects on rat pituitary gonadotrophs: (1) to antagonize the effects of estrogen, and (2) to reduce the response of gonadotrophs to GnRH-A. Thus, chlordecone is not estrogenic in rat pituitary cells in vitro.

Human cytomegalovirus-induced DNA polymerase and its interaction with the triphosphates of 1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-methyluracil, -5-iodocytosine, and -5-methylcytosine

Human cytomegalovirus-induced DNA polymerase and cellular DNA polymerase alpha were purified by successive chromatography on DEAE-cellulose, phosphocellulose, heparin agarose, and single-stranded DNA agarose columns. The purified virus-induced DNA polymerase was resolved to consist of two polypeptides corresponding to molecular weights of 140,000 and 58,000, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Virus-induced DNA polymerase and cellular alpha polymerase were examined for their sensitivities to the triphosphates of 1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-methyluracil (FMAUTP), -5-iodocytosine (FIACTP), and -5-methylcytosine (FMACTP). The inhibitive effects of these triphosphates on the DNA polymerases were competitive with regard to the natural substrates; thus FMAUTP competes with dTTP, and FIACTP and FMACTP compete with dCTP. The inhibition constants (Ki) for FMAUTP, FIACTP, and FMACTP of virus-induced DNA polymerase are 0.06, 0.30, and 0.47 microM, respectively. Cellular DNA polymerase alpha is much less sensitive to these inhibitors, and its Ki values for FMAUTP, FIACTP, and FMACTP are 0.45, 3.10, and 2.90 microM, respectively. In addition, human cytomegalovirus-induced DNA polymerase, but not cellular DNA polymerase alpha, can utilize these analog triphosphates as alternate substrates for their corresponding natural deoxyribonucleoside triphosphates in in vitro DNA synthesis.

Secretion of ovine luteinizing hormone in vitro: differential positive control by 17 beta-estradiol and a preparation of porcine ovarian inhibin

17 beta-Estradiol (E2) and an enriched preparation of porcine ovarian inhibin can positively regulate LH secretion in two different ways in ovine pituitary cell cultures. One major effect of these agents is to increase the sensitivity of cultures to low levels of LHRH or LHRH analogs. The second effect is to increase culture responsiveness to high levels of LHRH or its analogs. Prolonged treatment with 1 nM E2, for instance, increased pituitary sensitivity to D-Lys6-LHRH by 10-fold, since it lowered the ED50 of D-Lys6-LHRH from approximately 400 pM to about 40 pM; the maximum LH secretory response to D-Lys6-LHRH (1-100 nM) was not changed, however. In contrast, short term treatment with an E2-free preparation of porcine ovarian inhibin could increase, by 350%, normal LH responsiveness to high levels of D-Lys6-LHRH (1-100 nM), but had no effect on sensitivity; the ED50 remained unchanged. Chronic treatment with inhibin eventually increased sensitivity, and interestingly, a short treatment with E2 (6 h) caused a major increase in both sensitivity and responsiveness, but the responsiveness component usually disappeared between 6 and 48 h of chronic E2 treatment. Treatment with both E2 and the inhibin preparation caused the greatest increase in pituitary sensitivity to D-Lys6-LHRH (ED50 decreased to approximately 30 pM), but the increased responsiveness to D-Lys6-LHRH (1-100 nM) declined with time as with E2-only treatment. The different actions of E2 and the ovarian inhibin preparation seen to perturb different aspects of LH secretion. Therefore, study of these phenomena may uncover novel molecular details governing LHRH-stimulated LH release. Furthermore, these two types of LH secretory control may be physiologically important, at least in sheep, and perhaps in other animals as well.

Molecular epidemiology of cytomegalovirus infections associated with bone marrow transplantation

Restriction endonuclease analysis of purified viral DNA was used to study the molecular epidemiologic characteristics of cytomegalovirus infection in 18 patients having bone marrow transplantation. Four patients who had had asymptomatic excretion of cytomegalovirus in urine before transplantation subsequently developed a cytomegalovirus infection after transplantation (pneumonia in 2 patients, fever and viremia in 1 patient, and asymptomatic viruria in 1 patient). In each patient, the infection that developed after transplantation was caused by a cytomegalovirus strain genetically identical to the isolate detected in urine before transplantation. Cytomegalovirus isolates from different sites (buffy coat, lung, and urine) of the same patient were also identical, but cytomegalovirus isolates from different patients were never identical. Our results suggest that some cytomegalovirus infections after bone marrow transplantation may be caused by strains present before transplantation. The great structural and genetic variability of cytomegalovirus isolates must be considered in the development of effective diagnostic and immunoprophylactic measures for infection after marrow transplantation.